Sea coast - rocky seashore. Fish of Africa: Malawian cichids and fish of Tanganyika

Mbuna Group

The unusual hobby for cichlids in the early seventies is due to the appearance of the Malawian cichlid group "Mbuna", which received this name from local fishermen. The inhabitants of the rocky shores of Lake Malawi, feeding mainly on algae, covering rocks and stone placers with a lush carpet to a depth of 20 meters, were distinguished by an exceptionally bright color that competed with the color of coral fish. The most popular among "Mbuna" were representatives of the following genera: cynotilapia (Cynotilapia Regan, 1921), iodotropheus (Iodotropheus Oliver et Loiselle, 1972), labeotropheus (Labeotropheus Ahl, 1927), labidochromis (Labidochromis Trewavas, 1935), melanochromis (Melanochromis Trewavas, 1935), petrotilapia (Petrotilapia Trewavas, 1935) and pseudotropheus (Pseudotropheus Regan, 1921).

It turned out that by carefully selecting the communities of these vegetarian fish in terms of size, color, and temperament, one can create solid collections in one large aquarium, the device of which was described earlier. Instead of algae, lettuce, spinach, dandelion and even parsley leaves, steamed oats and peas, black and white bread, etc. can serve as food. Small additions of animal feed - coretra, daphnia, enchitra and bloodworm, high-protein dry feed (up to 20-30% of the total) - supplement the diet. Fish in the aquarium grow larger than in nature, and give numerous offspring. And, which is also very important, with such a diet, cichlids do not touch many aquatic plants.

Melanochromis Johanni (Melanochromis johanni (Eccles, 1973))- one of the most popular Malawian cichlids, which stands out for its exceptionally beautiful yellow-orange coloring of fry and females. Males with the onset of puberty completely change their color, becoming blue-black with two bright bluish-blue stripes along the body. Such a transformation for "Mbuna" is not uncommon, which, of course, causes understandable bewilderment among novice cichlid lovers. However, at an early age, it is quite difficult to distinguish between males and females. Ceteris paribus, males are somewhat larger and have more pronounced yellow spots-ki-releasers on the anal fin, similar to eggs. The size in nature does not exceed 8 cm, the females are smaller.

Reproduction is the same as other Malawians. The females, which incubate the eggs for three weeks in their mouths, hide among the rocks in shallow water.

Fuelleborn's labeotropheus (Labeotropheus fuelleborni Ahl, 1927)- very polymorphic and impressive appearance. Depending on the habitat, individuals are found from dark blue to blue and from almost orange to bright yellow with black-brown spots. For the elongated nose shape characteristic of the genus, the fish was also called the tapir cichlid. Under favorable conditions, the fish grow up to 18-20 cm, while the females are approximately 25% smaller. The habitat zone of labeotropheus in nature is limited by the upper seven meters of rocky ridges, lushly overgrown with algae, where they find places for feeding, shelter and spawning grounds. They are very territorial, especially during the mating season, and need a large aquarium, preferably at least 1.5 meters long. Spawning succeeds better in the cave, as it is noted that the fertilization of eggs occurs outside the oral cavity of the female and the fertilized eggs remain unprotected for a longer time than usual. Three weeks later, the females release the fry in shallow water, where their further development and growth take place in well-heated water. In conditions of aquarium cultivation at the age of 8-9 months, fish are already able to bear offspring.

Pseudotropheus zebra (Pseudotropheus zebra (Boulenger, 1899))- one of three species of Malawian cichlids that first appeared in Russia in 1973. Differs in surprising polymorphism. More than 50 natural color variants are currently known. The classic variations of the zebra have received the following generally accepted designations:

BB- (Black Bars) - striped zebra; corresponds to the traditional form of coloration in males with dark transverse stripes on a pale blue background;
AT- (Blue) - blue form;
W- (White) - white form;
OB- (Orange Blotch) - yellow-orange form with black-brown spots;
R.B.- (Red-Blue) - orange-red female and blue male, the so-called red zebra;
RR- (Red-Red) - a red female and a red male, the so-called double red zebra.

Other color variations Ps. zebra is named by indicating, together with the designation, the name of the area in which the capture was made. For example, the blue zebra from Maleri Island (Ps. zebra in Maleri Island); striped zebra Chilumba (Ps. sp. zebra BB Chilumba); golden zebra Kavanga (Ps. sp. Kawanga), etc.

It should be noted that the color of fish depends to a large extent on their age and condition. So, for example, fry of the classic striped zebra have a uniform grayish-brown color, which only at the age of 6-7 months begins to turn into striped in males and spotted in females; RB red zebra fry are brightly colored already at a young age, while females are orange-red, and males look dark gray and only become pale blue at sexual maturity.

Frightened during capture and transportation, the fish rapidly lose their brightness, which is almost natural for cichlids, so their true color can only be judged by adult active specimens grown using vitamin-rich feed and in a calm environment. If stronger territorial fish live in the neighborhood, Malawian cichlid juveniles may never (!) achieve the color characteristic of the species, and the only way to solve the problem is to put a group of fish weakened by constant stress of oppression into a separate aquarium. Here, normal coloration can be expected within a few days.

The apogee of the manifestation of the vital activity of fish and the development of secondary sexual characteristics associated with this - elongation of the fins, an increase in brightness and stabilization of color, the development of a fat pad in the forehead in males, etc. - is the repeated participation of fish in reproduction. The resulting cycles of mate selection, territory acquisition and defense, clearing of the intended spawning site(s), pre-spawning games with demonstrations of strength and beauty, spawning itself and the set of most vigorous actions determined by this contribute to the development of coloration and, if possible, to put it, the self-affirmation of males and females as true owners in the aquarium. At the same time, the amateur should not forget that the females of the Mbuna, as well as the males, are territorial and armed with sharp grater teeth that allow them to scrape algae from rocks, and they will not miss the opportunity to use them in defense and attack, when it comes to expulsion from its territory of a potential invader. That is why it is impossible to recommend the combination of females engaged in incubation of eggs in the mouth in small aquariums.

Black Sea, rocky shore: right from the water's edge, dense thickets of brown algae cystoseira begin. The branches of its huge - up to one and a half meters in height - bushes - stretch to the surface with special bags filled with air. Cystoseira beardedCystoseira barbata- the main algae-macrophyte of the coast in the Black Sea, a landscape-forming species. Epiphytic algae grow on its branches, fouling animals settle - sponges, hydroids, bryozoans, mollusks, sedentary polychaete worms; small snails and crustaceans feed on the dying cells of its bark, fish hide and make nests among its branches, and marble crab and crab are disguised under its color. invisible Macropodia longirostris, and numerous coastal fish of the Black Sea, and the tricolium snail - all who live in this underwater jungle, stretching along the rocky bottom of the Black Sea from the surface of the water near the coast to a depth of 10-15 meters.

Greenfinches over the Cystoseira Forest

The male greenfinch, having fertilized the masonry, protects it - drives away other fish from the entrance, ventilates the nest with a wave of the pectoral fins. Such paternal care for offspring is a property of most local fish - so do dogfish and gobies, whose clutches can be found under stones and large empty shells.

Greenfinches feed by nibbling the crusts of fouling animals from the branches of algae and the surface of stones - mollusks, worms, sea acorns. To do this, their fangs move forward, and the mouth turns into hard tongs-tweezers for cleaning underwater rocks - with their help, they pull out crabs and shrimps hidden in the cracks, crumble shells of mollusks and tubes of worms. Zelenushki live up to the lowest boundary of the rocky soil - 25-40m.

Graceful palemon shrimp live in the crowns of Cystoseira Palaemon elegans, small snails crawl along the branches - tricolia, bittiums - and many other animal species that feed on dying bark cells and periphyton on the branches of the host algae. There are also small predators here - for example, the polychaete oil worm Nephthys hombergii. The crown of each large algae is a whole world, a community of animals adapted for living together, epiphytic macroalgae and masses of microscopic organisms: these are bacteria, unicellular periphyton algae (mainly diatoms), amoeba and ciliates; small crustaceans - sea ​​goats and other amphipods; isopod crayfish - sea cockroaches idothea Idothea sp., harpacticides, balanus larvae and others.

flocks of mullet swiftly sweeping at a shallow depth, above the very crowns of algae - these are large fish with silvery scales. During seasonal migrations along the coasts of the Caucasus and Crimea (in spring - for feeding in estuaries, Azov, river mouths, in autumn - for wintering near the Caucasian, Crimean, Anatolian shores) they move in huge masses - hundreds of fish in one flock. That is why in April-May and in October we most often see dolphins off the coast - they are chasing schools of mullet. Several species of mullet live in the Black Sea, but we most often meet near the coast mullet singil Lisa aurata- not the largest - up to 30 cm species of these fish, which is easy to identify by the orange spot on the "cheek" - the gill cover. The mullet is an excellent swimmer, but it finds food at the bottom - it simply eats silt and even sand, raking the soil with its lower jaw like a shovel. What is edible will be digested and assimilated, and everything else will pass through the fish and end up at the bottom again. Fish that eat this way are called soil beetles, or detritivores. Since an unlimited amount of detritus is formed in the Black Sea, the food base of the mullet is inexhaustible. All species of mullet are able to live in both sea and fresh water (euryhaline fish), which gives them a huge advantage - mullet fry keeps in the mouths of rivers and in shallow water near the coast, where they are not threatened by marine predatory fish - bluefish, horse mackerel, garfish; they feed in limans and estuaries rich in nutrient silt, where salinity fluctuations are very large; and the mullet winters at a depth of more than 50 m under the steep shores of the Black Sea - in the most stable conditions.

Gray mullet Lisa aurata Other species of mullet in the Black Sea: becoming rare sharp-nosed Mugil saliens; larger mullet loban Mugil cephalus, widely distributed in coastal regions around the world. The large Far Eastern mullet brought by Soviet ichthyologists to the Black Sea in the 1980s breeds very successfully in the Black Sea estuaries and Azov. pilengas Mugil sojui. In recent years, the pilengas in the Black Sea is the main object of fishing from the shore - especially during its spring migration. Pilengas spring course near the beach VDC Orlyonok, depth 1-2m. A dark mass of hundreds of 30-50 cm fish can be seen from the shore.

flora and fauna of underwater rocks of the Black Sea - 40 meters down

As a child, I often went to visit my grandparents in the Krasnodar Territory, and I myself lived with my parents in one of the cities not far from the northern capital. For me, these “business trips” were a joy, three whole months on the street with friends, sun, heat, watermelons at 10 kopecks per kilogram. And after the vile climate of the north-west of our Motherland, this can generally be called a paradise. Many years have passed since then, and now I live with my girlfriend all in the same city. In the summer of 2010, the girl told me that our climate is bad, we should have a rest somewhere in the south - come on, she says, we’ll go to Egypt or Turkey. And then it dawned on me - why go to Turkey, when my relatives live in our south? That's what they decided on. And after a couple of weeks, we were already drinking tea with her in a carriage tapping on the rails. Next, a village with a population of 70 thousand inhabitants was waiting for us, 500 kilometers from the Black Sea. After staying with my grandmother for two days, we were sent to the sea by bus. To be honest, this part of the journey was much less pleasant: almost a ten-hour bus ride, in hot weather, without air conditioning - just a mockery.
We arrived at a Soviet-style pioneer camp located to the east of the village of Novomikhailovsky. It was built, apparently, a long time ago, but the management carefully followed it. The old houses, although they were built from crooked, dried boards, were completely painted recently. In general, the camp was quite tidy, well-groomed and did not at all create a feeling of abandonment and decline. A few words about how we got here: in the village where my grandparents lived, there was a single machine-building plant, and my grandfather had a friend who was one of its leaders. Through him, my girlfriend and I made a weekly trip to this camp almost free of charge. In fact, we were sent on vacation as factory workers.
The camp itself was located at a fairly high altitude relative to the sea, a beautiful view of the sea opened from the edge of the cliff, and at night you simply cannot imagine a more romantic place: a perfectly flat moon path appeared on the surface of the water, and it seemed as if you could walk along it. But the descent to the shore was a real hell for the well-fed (which, thank God, neither I nor my girlfriend are): a huge, long staircase passing through thickets of trees growing on the mountainside. Just before the beach (about ten meters to the end) the stairs appeared from the thickets of trees and from the beach one could see who was walking along it. Sometimes parents stood in this place and made sure that their children did not swim far. It took 15 minutes to fully climb the stairs. However, with all this, literally every five meters a lantern hung above the stairs, which made night walks along it very romantic. In general, for a young couple there was everything to have a great rest. The beach itself was located a couple of kilometers from the resort village - if my memory serves me, then it is called Novomikhailovsky - but at the same time this very beach is located between two ledges, and as a result it seems that there is no civilization around for many kilometers. This solitude was very pleasant to me and my girlfriend.
In this camp, I met my old friend - Zhenya. He himself seemed to be from Krasnoyarsk and also came for the summer to his grandmother in that very village in the Krasnodar Territory. In general, in childhood, we spent every summer with him together. I stayed in his house, and my girlfriend went to our house. When I was chatting with Zhenya, a most amusing idea suddenly came into my head, as it seemed to me then: to scare my girlfriend. Having laughed, Zhenya and I developed a plan: on the last night before leaving, the girl and I were going to take a walk along the beach at night, at that very moment Zhenek in a black mask from the Scream was supposed to crawl out of the thickets and start chasing us. We also agreed that when I run away, I will lead the girl to a dead end in the rocks, and at that moment Zhenek will take off his mask, and we will all laugh together.
The next night, as planned, my girlfriend and I went for a walk on the beach. The weather was simply amazing: calm, smooth water, like glass with a moonlit path, the silence is broken only by a slight swaying of the water. We walk along the shore, pebbles rattle under our feet. Slowly, we began to approach the thickets, and I already began to chuckle to myself. Suddenly, Zhenek comes out of the thickets - it must be admitted that he managed to get out spectacularly; I was afraid that getting out of the bushes, he would make a noise and screw up, spoiling the rally from the very beginning. But he did not disappoint: he stepped out of the thicket with even, straight steps, pebbles crunched under his feet. I felt my girlfriend's nails dig into my hand, so hard that I almost screamed. For a second we froze, and then Zhenek suddenly walked sharply in our direction (at that moment there were fifteen meters between us). At the same second, the girl screamed and ran in the opposite direction (we walked towards the stairs), dragging me along with her. We ran very fast, my slates even flew off my feet, and the girl kept dragging me along with her. I turned back and saw Zhenya following us - he walked with a quick, confident step, and looked very scary in the moonlight: somewhere he found something like a black hoodie, long, to the very ground, and there was a hood on his head. I chuckled to myself and abruptly dragged my girlfriend towards the very dead end we agreed on. In fact, we ran away not far - the stairs with flashlights were perfectly visible from here. Having run into a dead end, I dragged the girl with me into a corner that was hidden from the moonlight, we pressed our foam against the cold stone and froze. I covered the girl's mouth with my hand and gestured: "Shh!". I myself was already bursting with laughter, I was ready to neigh like a horse at any moment. But the girl was trembling so much that I thought the stone behind us was about to shake. Suddenly, very close by, we heard the crunch of pebbles under our feet. The footsteps came closer, all at the same steady pace. Zhenek appeared in front of the stones, he stopped abruptly and seemed to peer into the darkness. The girl grabbed me with her nails again. Zhenek began to move in our direction, but with slower steps. After taking a few steps, he stopped again and began to turn his head.
And then for some reason I stopped bursting with laughter, the fun inside was replaced by confusion, and a slight chill ran down my back: I heard Zhenek, turning his head from side to side, sniffing. Yes, he sniffed like a dog looking for a trail. A variety of thoughts flashed through my head, and a shiver went through my body. Still not believing in the reality of what was happening, I was numb and could not move. And then my brain gave me a chilling thought: Zhenya’s “Scream” mask, although it was black, was made of glossy plastic, which in the moonlight, even under the hood at least once, would have reflected the moonlight. And the one in front of us had solid black under the hood. Now, realizing that it was not Zhenya standing seven meters in front of me, I realized that I needed to act. I turned and looked at the girl, she closed her eyes, trembled, but did not make a sound. With my bare feet, I carefully groped for the pebbles, afraid to make any sound. I managed to put one of the stones on my foot. What stood in front of us continued to turn its head and sniff, but did not move from its place. Horror fettered my whole body, but I understood that we could not stand here like this all night and not make a sound. And suddenly one of the lanterns on the stairs blinked. I began to peer and realized that the lantern did not blink at all, just someone passing by blocked its light. And then I broke out in a cold sweat. In the distance I saw Zhenya, who was carrying a mask in his hand. I was ready to scream in fear, but, thank God, I restrained myself and in the next second I swung my leg and launched the stone forward. The stone rang loudly, and at the same moment what was standing in front of us soared (I can’t call it a jump) a couple of meters into the air and collapsed where the stone hit. The girl screamed, I, without wasting a second, grabbed her with all my might and rushed towards the stairs. The girl kept screaming, the echo rolled along the beach, and in my ears I heard only the wild beating of the heart and the roar of the pebbles behind us. This creature realized that it had been deceived, and now it was rushing after us in a completely different way than before: it ran, covering two or three meters with one step. I squeezed everything I could out of myself, and now we were already running along the iron stairs ...
When we got to our house, the girl was already just sobbing and writhing in hysterics. I rushed to calm her down and said that it was a hoax, that our pursuer was my friend Zhenya, with whom I agreed to scare her. I must admit that I did not think that she could hit me like that, but in a second I was already sitting on the floor, and my eyes were swimming from a sickly blow to the jaw. The girl collapsed into bed, still sobbing, but after a while the sobs stopped and she fell asleep. I lay and looked at the ceiling. I still couldn't believe it all. And why Zhenya and I ...
Zhenya! I completely forgot about him, but he stayed somewhere with this creature. I wanted to run back, but I couldn't. Fear kept me from getting out of bed. I stayed in bed and stared up at the ceiling. After a while, fatigue took its toll and I fell asleep.
The next day we packed our things and prepared to leave. The girl did not talk to me, and the training camp was dull. And I still had a feeling of fear. When we were stuffing things into the luggage departments, I ran into Zhenya, who also did not want to talk to me at first, and then said that, as promised, he went downstairs, climbed into the bushes, but then he wanted to relieve himself, and he went in deeper into the bushes. Then a wild cry of a girl rolled along the beach, and then he heard a clatter on the stairs. When he got out of the bushes, there was no one on the beach. He thought that we scared him on purpose. As a result, Zhenek was offended, the girl did not talk to me for another two days, and for some time I could not sleep at night and was shaking with horror.

Snow flakes, so softly falling on the mountain peaks, are the most destructive force. They form into snow caps many meters thick. The lower layers of the caps under the pressure of the upper ones are converted into ice. It binds protrusions, penetrates into cracks and clefts. And the snow keeps falling, and the ice, under the influence of its own gravity, begins to slide down the slope, dragging away stone blocks and slabs. Usually the movement is so slow that only the widening breaks in the snow cover give it away. But sometimes a huge layer suddenly breaks off from all supports, and thousands of tons of ice, snow and stones roll into the valley.

All the big rivers, the Amazon and the Zambezi, the Hudson and the Thames, as well as thousands of lesser ones, reach their estuary completely muddy with rainfall. Even the most transparent river waters are full of microscopic particles - mineral and decomposed organic substances. Mixing with salts dissolved in sea water, they stick together and sink to the bottom, forming huge mudflats.

Estuary silt has a very special texture, stickiness and smell. If you step into it, it will stick to your leg so much that it can tear off your boot. It is so fine-grained that the air does not seep through it, and the gases released by the decaying organic residues inside it remain there until they escape from under your soles, dousing you with the smell of a rotten egg.

Twice a day, the nature of the waters washing these mudflats changes dramatically. At low tide, especially when the rivers are swollen with rain, fresh water predominates, while at high tide, the water in the estuary can be equal in salinity to sea water. And twice a day, a significant part of the silt can come out of the water into the air. It is quite obvious that organisms living in such a place must be resistant to numerous changes in physical and chemical conditions. But the benefits associated with this are very great, for the estuary receives daily food from both the river and the sea, and potentially the water in it is richer in nutrients than any other - both salty and fresh. And therefore, those few organisms that withstand such stringent requirements thrive there in incredible numbers.

At the upper end of the estuary, where the water is only slightly brackish, live thin as hairs tubule worms. Their front end is immersed in the silt into which they eat, and the back end waves in the water in order to better be washed with oxygen. Up to half a million of them can live on one square meter of silt, and they cover it like thin reddish-red wool. Closer to the sea, where the water is slightly saltier, hordes of centimeter-long crustaceans build burrows for themselves and sit in them, capturing the passing nutrient particles with hooked antennae. Tiny, wheat-sized rissoid snails extract food from the upper creamy layer of silt, and with such success that more than forty thousand of them were extracted from one square meter.

Closer to the ebb tide, especially where sand is mixed with silt, sandworms live. These worms also feed on silt, but enrich it before they consume it. Each sandworm, about forty centimeters long and as thick as a pencil, digs a hole in the form of a steep arc with two exits to the surface and strengthens the walls, lining them with mucus. It fills the upper part at one exit from the arc with loose sand, and then, clinging to the walls with bristles on its sides, it begins to move back and forth along the bottom of the mink, like a piston in a pump, drawing water through its sand filter. The organic particles it carries get stuck in the sand. Having ceased pumping water, the worm begins to eat sand, digesting everything edible in it, and spewing the rest into the other horn of the arc. Approximately every three-quarters of an hour, he pushes the spewed sand out of the mink, so that neat pyramids form at the exit. In the same place, at the very surface of the water, heartworms are buried. These mollusks do not compete with sandworms for silt, but suck up food directly from the water through two short, fleshy siphons.

At low tide, all these creatures stop feeding and take steps to keep themselves from drying out. The silt around the rissoids has not yet completely compacted, and the water, receding, carries away most of it, and tiny snails lie on top of each other in layers a few centimeters thick. Each seals the entrance to the shell with a small disc that completes its leg. The cockles tightly squeeze the valves of their shells, and the sandworms simply remain in the mink, which is so deep that the water does not escape from it.

But desiccation is not the only danger threatening these creatures during low tide hours. All of them are vulnerable to air attack, and hungry birds now flock to the estuary. The food they choose is largely determined by the size and shape of the beak. Crested duck and red-headed pochard rummage through the silt and grab tubifexes. Plovers and plovers with short sharp beaks gorge themselves on rissoids, extracting the body of the mollusk coiled in a spiral with a lightning strike. Herbalists and sandpipers, whose beaks are twice as long, probe the top layer of silt in search of crustaceans and small worms. Oystercatchers with strong scarlet beaks specialize in heartworms. Some open shell shells, others choose smaller and thinner shells and break them. Curlews and Godwitches, who have the longest beaks, reach the sandworms and extract them from their burrows.

And the river still carries new sediments, and the shoals are gradually growing. A green film of algae begins to form on them, compacting particles of silt. As soon as this happens, other plants can already take root in it. Now the silty shoals begin to rapidly rise higher and higher, as the particles of silt brought by the splashing waves are no longer carried back by the ebb, but are retained by the roots and stems of plants. Little by little, they rise so high that they hide under water only at the highest tides. Their shores are strengthened, and the inhabitants of the estuary have to cede their territory to the inhabitants of the land.

On the European coasts, an active role in this process belongs to the saltwort, a small plant that, with scale leaves and swollen translucent stems, resembles desert succulents. Actually, the similarity is not simple. Flowering plants have evolved on land, and all their chemical processes are connected with fresh water. Sea water is dangerous for them, because due to the salts dissolved in it, its density is higher than that of their juice, and their roots begin to exude moisture, and not absorb it. Therefore, plants in a salty environment need to accumulate moisture in themselves just as much as cacti in the desert.

In tropical estuaries, silt is retained by mangrove forests, consisting of shrubs and trees - both low and twenty-five meters high. They come from different families, but the conditions of life in brackish swamps led to the development of similar features in all of them.

Trees first of all have to solve the problem of how to survive in viscous unsteady silt. Deep roots are useless here, because warm silt already a few centimeters below the surface is deprived of oxygen and sour to causticity. This is why mangrove trees have a flat root system that rests on the surface of the mud like a raft. Taller trees receive additional stability due to the curved roots extending from the middle part of the trunk, which serve as props for it. At the same time, the roots must provide the tree not only with stability, but also with nutrition; and the horizontal position of the mangrove root system contributes a lot to this, since the nutrients necessary for the tree are not buried in acidic mud, but lie on its surface, where they were left by the tide.

The roots also help the tree get oxygen and get rid of carbon dioxide, a product of its life processes. Again, there is no oxygen in the mud. Mangroves get it directly from the air through small areas of spongy tissue in the bark on prop roots. In the same mangroves that have not acquired such roots, this tissue is located on the nodular vertical outgrowths of horizontal roots. The mangroves that grow closer to the sea have developed conical respiratory roots that, unlike ordinary roots, grow vertically upwards, outpacing the silt that settles there faster, and surrounding the tree with countless rows of sharp pegs that most of all resemble some kind of fantastic defensive system in the medieval spirit.

Salt causes the same problems for mangroves as it does for saltwort. They also have to keep moisture in their tissues, and they prevent it from evaporating in the same ways as desert plants - dense waxy skin on leaves, the location of stomata at the bottom of tiny dimples. But they still need to prevent the accumulation of salt in their tissues, which would seriously disrupt their life processes. Some mangroves manage not to draw it in with water thanks to a special membrane that covers the roots, as, in particular, in saltwort. Others, deprived of such protection, suck up the dissolved salt by their roots, but get rid of it before its concentration becomes dangerous. They either have special organs in the leaves that exude a rather strong saline solution, or from the juice it enters the already drying leaves, which then fall off along with all the excess salt.

As silt accumulates on the seaward side of the mangrove swamp, mangrove plants immediately master it with the help of special seeds that germinate on branches and release a stem that reaches almost half a meter in some species. Some of these seeds fall straight down on the tangled roots and take root there. The underside releases roots, and the stem unfolds the leaves. Others fall at the height of the tide, which carries them away. In brackish marsh water they float upright, but if the tide drags them out to sea, in denser sea water they rise higher into the air and capsize. In this horizontal position, the green skin cells begin photosynthesis and nourish the young plant. The tender bud at the end, which is to be given leaves, remains moist, not scorched by the sun, and cools all the time. In this position, the mangrove baby remains alive for up to a year, having traveled hundreds of kilometers during this period. If the current eventually carries it into another estuary with less saline water, it will again assume a vertical position, with its roots down. When at low tide the tips of the roots touch the soft silt, they begin to grow into it and branch at high speed, and after a while a new mangrove tree rises to the sky.

The mangrove swamp can be crossed by several free channels, but in general it is so densely overgrown that even the smallest and narrowest shuttle gets stuck there. If you intend to explore such a swamp, you can do this only on foot during low tide hours. This is not the best place to walk. Thick, curved support roots constantly sag under your weight and the foot slides off. Many are lined with sharp shells that scratch your shin if you slip, or split your palms if you try to hold on to them so as not to fall headfirst. Everywhere smells of rot. Water drips and trickles down from the roots. Clicking sounds are heard in the stuffy air - these are crabs and mollusks hiding in their shelters, tapping their claws and slamming their shells. Mosquitoes squeak all around and sting you mercilessly. The branches overhead are so intertwined that not the slightest breeze brings coolness, and the air is so saturated with dampness that sweat pours from you in hail. And yet, the mangrove swamp has a peculiar undeniable beauty. Water seeping through the roots casts silvery reflections on the undersides of the leaves. Crossing arcs of support roots, pegs sticking out of the silt and nodes of respiratory roots form endless patterns. And life is everywhere.

A whole army of various animals is busy collecting food left by the ebb. Small littorin-like sea snails slowly crawl along the silt, eating scraps of algae. Ghost crabs, five centimeters across, scurry about it in search of organic debris, looking for danger with eyes that are not placed on the tips of long stalks, but surround them, providing the crab with a 360 ° field of view. Alluring crabs carefully emerge from their holes and are accepted to process the surface layer: they grab a dense lump with claws and bring it to a pair of jaws bordered with bristles, moving back and forth in front of the mouth opening. The lump of grains of sand is held together by the spoon-shaped bristles of one jaw, while the others sweep all the nutritious particles from it into the mouth behind. Inedible grains of sand accumulate in the lower part of the mouth apparatus, where they are compacted into a ball, which the crab picks up with its claws and throws it away, moving to a new place to repeat the whole operation from the beginning.

The females of the fiddler crab use both claws, while the males are forced to make do with one claw, the same as that of the females, while the second is noticeably larger and brightly colored in pink, blue, purple, or shines with white. Its purpose is to serve as a signal flag. The male waves it to the female while doing pirouettes. In different species, choreography and semaphore are combined in their own way. Some rise on tiptoe and draw circles with their claws, others frantically swing them from side to side, others do not move their claws, but bounce. But the meaning is always the same: the male is ready to mate. The female, having learned the signal of her species, sooner or later will run up to the male, follow him into his mink, where they will mate.

Crabs originated in the sea, where most of their species still live today, breathing with the help of gill chambers inside the shell, through which oxygenated water is passed. Fiddler crabs, however, also need to breathe in the air. They solve this problem simply by keeping water in the gill chambers. Naturally, oxygen in such a small amount of water is soon depleted, but the crab immediately renews its supply, driving water through the mouth apparatus and whipping it into foam. The newly oxygenated water returns to the gill chamber.

Fish also come out of the water and crawl through the silt of the mangroves. These are mudskippers. The largest of them are about twenty centimeters long. Like crabs, they store water in the gill chambers, but they cannot enrich it with oxygen and regularly return to the ducts to replace the previous supply with fresh water. But these fish have an absorbent surface that hard-shelled crabs lack: skin. And a significant part of the oxygen they need is obtained through it, much like frogs. However, for this the skin must be moist, and jumpers from time to time quickly roll over the silt to wet the sides.

When they need to rush forward quickly to grab a crab or avoid danger, they turn their tail to the side, snap it and fly through the mud like a bullet. However, they usually move much more slowly, relying on pectoral fins, which have bony supports inside the body, are controlled by strong muscles and are equipped with a joint, so that it looks like the jumper is crawling, leaning on his elbows. In some species, another pair of fins closer to the abdomen has merged into a sucker, with which such mudskippers can be held on roots and trunks.

These fish live in mantras in many areas of the world. There are usually three main species in each swamp. The smallest stays in the water the longest and gets out of it only at low tide. Flocks of them crawl in liquid silt at the water's edge, filtering it in search of small worms and crustaceans. The area flooded in the first hours of the tide belongs to noticeably larger jumpers. These are vegetarians, content with algae and other single-celled plants. Each fish has its own area in which it digs a hole for itself, jealously guarding the silt around. Sometimes it encloses its territory with low ramparts of silt with a total length of several meters in order to prevent neighbors from entering it, and also to some extent prevent complete drainage of the silt. Where the populations are numerous, these areas merge and the entire shoal is divided into polyhedrons. Inside each walks the owner, like a bull through a fenced meadow. The third type of mudskipper occupies the highest part of the swamp. These are predators that prey on small crabs. They have holes, but the rights to the surrounding territory are not claimed, and several jumpers can search for prey in the same area without disputing it from each other.

Mudskippers not only feed out of the water, but also conduct mating courtships there. Like most fish, they wave and vibrate their fins. Since both pairs of fins are used for locomotion, two long dorsal fins are used in the courtship ritual. Usually they are pressed to the back, but, starting courtship, the male rears them, and they amaze the eye with the brightness of their color. But this alone is not enough to attract a friend: on a flat swamp, a small fish is visible only to its neighbors. Therefore, the male jumper, demonstrating his beauty to the largest possible number of spectators, beats with his tail and soars up, unfolding the banners.

The species that lives at the water's edge, as far as is known, does not care about its offspring in any way. The low tide carries away the fry as soon as they hatch, and the tiny jumpers join other fry and larvae drifting near the sea surface. The vast majority of them will become someone's prey or will be carried away to the open sea far from the mangrove swamps, and they will die.

The second species, however, provides some protection to its young. The male digs a hole in the middle of a fenced area and surrounds the entrance to it with an annular shaft. The silt here is so close to the level of non-flowing water that a pond forms inside the shaft. The male is located on the shaft, where the female comes to him. Mating takes place in a secluded burrow at the bottom of a pond. Caviar is laid there, and fry remain there even at the height of the tide, until they grow up so much that they are already able to escape from enemies.

The third type of mudskippers does not build ponds - perhaps at a higher level they would be poorly filled. But their minks are very deep and go into the mud for more than a meter. And there is always water at the bottom, so at first the juveniles are protected.

Mudskippers, like alluring crabs or oysters, are essentially marine animals that have adapted to spend part of their life in water, and part in the air. And some animals moved to the swamp from other places and adapted to the same.

In Southeast Asia, a small snake crawls into mangroves to hunt mudskippers, which even penetrates into their holes. She is perfectly adapted to life in the water: her nostrils close, and a special valve closes in her throat when she opens her mouth under water to grab prey. Another snake, a close relative of the first, does not hunt fish but crabs, and has developed a poison that is especially effective on crustaceans. The third snake on the nose, oddly enough, has two movable tentacles that help her navigate the muddy water. These swamps are also inhabited by an amazing frog, the only one in the world whose skin can withstand contact with salt water. She feeds on insects and crustaceans.

The most enterprising, curious and omnivorous visitors to the mangroves are monkeys, crabeater macaques. Macaques on their hind legs fearlessly enter the water up to their waists. Crabs are his favorite treat. Usually, the agile crab first manages to slip away from the monkey into a hole, but the monkey settles down near the entrance and waits patiently. In the end, the crab cautiously looks out, checking if everything is calm around, and then the monkey grabs it. But he should be careful, because the crab has claws, and often the hunt ends with the furious cries of the monkey, which waves its injured paw in the air.

Twice a day the huge silt arena juts out into the air and is flooded twice. Water returns quickly and silently. The balls of roots disappear under the running ripples, and the mangrove forest is transformed. For some of the inhabitants of the silt - worms, crustaceans and mollusks - this brings a pleasant respite. They are no longer in danger of being attacked from the air or in danger of drying out. But for others, things are getting worse. Some crabs are so adapted to breathe air that they die when immersed in water for a long time. And everyone builds a vault over his mink that holds an air bubble - oxygen in it is enough for the crab until the next retreat of the water. Small mudskippers climb up the roots as if fleeing a flood. Perhaps these are young individuals who have not yet acquired their own territories, and therefore they do not have a mink to hide in when large hungry fish swim in with the tide in the mantras. Yes, juveniles, perhaps it is safer to wait out the tide in the air.

Algae-eating sea snails also crawl up the roots next to jumpers. If they remained on the muddy bottom, where there are no stones with secluded cracks, they could also become victims of fish. However, they are not able to move at the speed of jumpers, and it is difficult for them to stay ahead of the rising water, and therefore they leave their silt pastures long before the tide water comes to them, demonstrating an amazingly accurate sense of time. Their internal clock gives them even more complex signals. On certain days of the month, the tides are exceptionally high, and the snails would not have had time to climb out of reach. During such periods, they not only do not descend into the mud between high tides, but, on the contrary, crawl higher along the mangrove roots so as not to be trapped.

Insects that fed on the silt, also fleeing from the water, are in abundance on the mangrove roots and under the leaves. However, even there they are in danger. Along with other fish, counting on something to profit from in the mangroves, archers swim there, keeping close to the surface of the water. They are more than twenty centimeters long, their eyes are large, and the lower half of their mouth is protruding. Their eyesight is so sharp that, despite ripples and refraction, they distinguish an insect sitting above the water. Having outlined the prey, the archer presses its tongue against a long groove in the palate, abruptly closes the gill covers and throws up a jet, as if from a water pistol. The fish may have to repeat this operation once or twice, but it does not give up, so in the vast majority of cases the jet eventually knocks the insect into the water, where it is immediately swallowed. Insects nestled higher attract other predators. Ghost crabs climb trees, turn over leaves and grab the flies sitting there with their claws.

Refugees hiding on the roots remain under siege for several hours. But then the ripples on the water disappear, and for several minutes it seems motionless. The tide begins. Ripples appear again, but now they go around the roots on the opposite side: the swamp is again gradually drained. As the water leaves, it leaves a fresh supply of edible bits for crabs and mudskippers, as well as a new layer of sticky silt that expands the mangrove's territory just a tiny bit at the expense of the sea.

If land advances in the estuary, then in other places the offensive is carried out against it. Where the seashore is not protected by sediments, and especially where it forms cliffs, the waves beat at its base. During storms, the waves, raging, throw sand and heavy stones into the cliff. This constant bombardment unmistakably reveals all the weak points of the cliff - the cracks hiding in it, the slightly softer layers of the rock - and over time they turn into deep clefts and caves. The land is receding, and only lonely bizarre rocks remind where its former border passed not so long ago. Larger stones hit the very bottom of the steep bank, causing it the greatest damage, undermining it. And here comes the big chunk. For some time, a pile of stones will protect the base of the cliff. But little by little, the sea takes possession of the debris - it rolls the larger ones from place to place, crushes the small ones into very very small fragments, which are then picked up by the coastal current and carried away with them. Once again the cliff is deprived of protection, and the sea resumes its attack on land.

Animals not only live in this dangerous zone of destruction, but also contribute to it. Sea borers are bivalves that live in soft rocks like limestones or sandstones. The valves of their shells are connected not by ligaments, but by a kind of hinge. The mollusk puts out a fleshy leg from one end of the shell, attaches to the rock, and then presses the jagged edges of the valves to its surface and, swaying from side to side, scrapes the stone alternately with one or the other valve. Very slowly, a small hole turns into a tunnel up to thirty centimeters long, at the far end of which the driller is located, extending two connected siphons along the stone corridor outward, in order to suck in and throw out water through them, in complete safety from the impacts of the stones played by the waves. But a quiet life continues only until the block of stone is so worn out that it falls apart into pieces. Then the driller should immediately start drilling a new tunnel, as long as it is intact.

Sea dates also climb into limestone, but not by drilling through them, but by dissolving the rock with acid. Their own shells, like those of any molluscs, consist of the same substance as limestone - calcium carbonate, and the acid would dissolve the shells at the same time, if they were not covered with a brownish stratum corneum, which gives them a resemblance to dates. The higher above the ebb line a marine organism lives, the greater the difficulties it faces: it stays out of the water longer between high tides, it can move more easily in the sun and receives more abundant doses of very unpleasant rain jets. This hazard scale has led to clear zones. Each is dominated by organisms best able to cope with this combination of difficulties, and therefore the rocky shores are striated in the most striking way.

Unlike silt, rocks offer plants a secure foothold, and rocky shores are usually clad in seaweed. At first glance, it may seem strange that in the sea there are no plants comparable in complexity to the flowering plants on land. But in the latter, a significant part of the tissues serves to solve problems that do not exist in the sea. A plant on land is forced to diligently absorb water, without which life is impossible, and distribute it to all parts of its body. It should pull the crown up so that competitors do not shade it, do not deprive it of the necessary share of sunlight. He needs the means by which the male and female cells are connected, and the means by which the seeds get to new places. And therefore, on land, plants acquired roots, stems, trunks, leaves, flowers and seeds. But in the sea all these problems are solved by water. It provides the algae with both support and all the moisture they need. She also transfers germ cells when they are released, and scatters spores. Since algae do not have vessels full of juice, the salinity of the water does not create any problems with the preservation of their internal fluids. Seaweeds, like all other plants, except for fungi, naturally need sunlight, and it does not penetrate particularly deep into the water column. Therefore, algae for the most part either swim freely or attach to the bottom, but where it is relatively shallow.

Just below the low tide, brown algae and kelp grow - they are very reminiscent of belts and in some places form dense masses of multi-meter ribbons swaying near the surface, where it is light. They firmly cling to stones with rhizoids, which, unlike the roots of land plants, do not have an absorption function and serve simply as anchors. These algae withstand some contact with air at especially low tides, but they cannot live closer to the coast. There, their place is taken by fucuses, smaller plants with gas bubbles in the blades, thanks to which they stay near the surface closer to the light. Fucuses of other species live even higher. The water is never deep there, and these fucus do without bubbles in short blades that do not need to be lifted. All these algae of the intertidal zone have a surface covered with mucus, which retains moisture for a long time and protects them from drying out. Species near the highest limit endure contact with air for four-fifths of the time. Many other types of algae also grow along the coast, but brown ones predominate almost everywhere and give each zone its characteristic appearance.

Some coastal animals also settle in certain zones. At the highest level, inaccessible even to the most unpretentious fucuses, where even the highest tide does not reach, and sea water enters only in the form of splashes, tiny sea acorns live. Attached to stones, tightly closing the shell lids, these barnacles perfectly retain the very small amount of moisture they need inside. Their need for food is so small that they, incredibly, manage to extract sufficient nutrition from the spray.

Somewhat lower, the rocks are often surrounded by a dense bluish stripe of mussels. These mollusks are not able to stay in the air for as long as sea acorns, which defines the upper limit of their habitats. The lower one is set by starfish. The hunting techniques of these predators are straightforward, time-consuming, but destructive. The star climbs onto the mussel, clasps it with rays, along the lower edges of which there are suction cups, the so-called ambulacral legs. Slowly, slowly, the star opens the shell valves, protrudes the stomach from the oral cavity in the center of the body, presses it with a gasket to the soft parts of the mussel body, dissolves them and sucks them up. Starfish swarm on the seabed just below the lowest tide line and devour various mollusks there. It is very difficult for mussels to survive in such conditions. But out of the water, starfish cannot feed, although they do not die immediately in the air, and therefore, half a meter above low tide, the conditions for the existence of mussels are already more favorable, and two or three meters above it, they completely take over the shore.

Mussels are attached to stones with a bundle of sticky threads, and where the surf is relatively strong, it is difficult for them to hold on. Then their place can be taken by relatives of sea acorns - sea ducks. Their body, the size of a large bean, is enclosed between calcareous plates, and they are securely held on stones with the help of a long, wrinkled stalk as thick as a little finger.

In this intertidal zone, next to mussels and sea ducks, there are many other animals that, however, do not occupy such a dominant position. Sea acorns, larger than their relatives in the splash zone, settle on mussel shells. They feed on nudibranch snails, mollusks without shells. In the recesses between the stones, where the water remains even at low tide, multicolored sea anemones wave their tentacles. Round sea urchins, bristly like pincushions, slowly crawl over the stones, scraping algae from them with teeth protruding from the mouth opening in the middle of their ventral side.

Although these zones with specific communities of animals and plants seem so clear-cut, and their boundaries so definite and strict, they can by no means be called permanent and unchangeable. Their inhabitants are always ready to take advantage of the slightest opportunity to expand their territory. A strong storm is enough to pluck a couple of mussels - a bald spot forms in their continuous carpet. And here the waves can tear off their entire strips. And in the water there are always tiny fleets of larvae, both mussels and barnacles, just waiting for the opportunity to attach themselves somewhere. And it is likely that sea ducks will be able to capture a bridgehead in the territory of mussels.

On the northwest coast of America, a seaweed has developed a way of actively invading mussel banks. Its elastic half-meter stem ends with a corolla of curved slippery plates, giving it a resemblance to a miniature palm tree. This peculiar crown allows algae to deal with mussels. In the spring, a young algae, thanks to a happy coincidence, can cling to the mussel shell with this adaptation. In the summer, at low tide, the sea palm throws out spores that slide along the plates onto the surrounding mussels and get stuck between them. With the onset of autumn storms, waves that under normal circumstances did not cause much discomfort to mussels can fall under the crown of a palm tree and carry away the algae. Since the algae attaches to the shell more firmly than the mussel itself to the stone, it drags the mussel with it. Now young sea palms on a mussel bank get more space and quickly occupy the cleared stone with a new generation.

Taken individually, these inhabitants of the seashores cannot count on a long life. Sooner or later, the restless waves will crush the stones into powder. Shore currents pick up the fragments and carry them away, continuously sorting them by size, and then throw them off the lee side of some cape or line the bottom of the bay with them.

On such sandy shores, life is much poorer than in other places of the littoral - the border strip between sea and land. Here, each wave of each ebb and flow plows the surface of the sand for at least a few centimeters, so that the algae cannot gain a foothold. Therefore, herbivorous animals do not form communities there. And the rivers don't bring food supplies there twice a day. The edible particles that are left on the sand by the waves cannot provide food for any large animals, because the layers of sand act like filters in sedimentation tanks. The constant supply of oxygenated water to the sand allows bacteria to freely exist up to a certain depth. And they quickly decompose and absorb about 95% of all organic matter brought by the waves. Therefore, no worm is able to exist by eating sand, like worms in mantras - silt. The inhabitants of the sandy shore, extracting food from the water, must be ahead of the bacteria living in the sand.

Sabellida worms get out of the situation by gluing together a tube of grains of sand and fragments of shells, the end of which sticks out a few centimeters above the sand, and sticking out a whisk of tentacles from it to select edible particles suspended in water. For safety, marine cuttings are buried in the sand, but they expose two tubes above them into clear water and suck a stream through them into the filter between the wings. The mask crab leads a similar lifestyle. It does not have a fleshy siphon like molluscs do, so it constructs a suction tube by putting two antennae together. Some types of sea urchins also bury themselves in the sand. Their needles are much shorter than those of their relatives, the inhabitants of the rocky shores. With the help of these needles, they dig in, rotating them, as if on hinges, which makes these sea urchins look like miniature threshers. Having dug in, the hedgehog fastens the grains of sand around with mucus, thus constructing for itself a chamber with strong walls. Sea urchins, like starfish, have ambulacral tubular legs. In burrowing hedgehogs, a pair of legs is very lengthened, and the hedgehog exposes them through the sand. Cilia covering the legs drive water through the tubes, so that the hedgehog receives oxygen and edible particles dissolved in it through one, and spews waste through the second. These urchins hiding in the sand are rarely seen alive, but their beautiful whitewashed skeletons are often carried by the waves onto the beaches. A species that burrows relatively deep is heart-shaped, while those living closer to the surface are round and flat.

Most of the food on the beach - to the great inconvenience for so many marine animals - accumulates at the upper tide line, where the waves leave a large amount of all kinds of organic residues: scraps of brown algae and fucus plucked from rocks, jellyfish that the wind drove to the shore, dead fish , shellfish eggs - the terms change from high tide to high tide and from one season to another. Sea fleas - amphipods - get all the moisture they need from wet sand and hide for most of the day under wet heaps of algae thrown onto the beach. When the air cools with the onset of night, they get out - 25 thousand per square meter - and begin to destroy decaying plants and animal corpses. But they are the lucky exception. Most of the marine inhabitants of the beach are not able to get to these riches.

However, on the southern coast of Africa, one mollusc, the puddlefish, has perfected a very ingenious way to get to these hoards with a minimum of effort and with a minimum of risk. The snail lies buried in the sand near the ebb tide. As the tide rolls over her shelter, the plow crawls out of the sand and sucks water into her leg. The leg swells and takes a shape resembling a plowshare, although its function is closer to a surfboard - the wave carries it, and hence the snail, higher to the shore, lowering the mollusk onto the sand in the same place as its other cargo. This snail is very sensitive to the taste of decomposition products in water and, having found it, draws in its leg and crawls to where it is stronger. Around a dead jellyfish, dozens of plowfish gather in a matter of minutes. They immediately start eating until the tide reaches its highest point and their prey is surrounded by water. It is dangerous for them to be at the upper tide line: busy with food, they can miss the beginning of low tide and remain on a dry shore. When the water rises higher, the plows leave their prey and dig themselves into the sand, from which they get out only at low tide, inflate their legs and roll down with the waves to a great depth, so that there they wait in the sand for the next tide.

Only a few marine animals are able to stay alive, having fallen beyond the upper limit of the tide. Turtles for such excursions are forced by their origin. Their ancestors lived on land and breathed the air. Over countless millennia, sea turtles have become excellent swimmers, learned to dive and stay under water for a long time, and their legs have changed into long wide flippers. But turtle eggs, like the eggs of all reptiles, can only develop in the air - the embryo needs gaseous oxygen, otherwise it will die. Therefore, every year, sexually mature female turtles, having mated in the ocean, must leave its safe expanses and get out onto land.

Ridleys, perhaps the smallest of the sea turtles, at just over half a meter long, breed in colossal aggregations that are a most amazing sight. On two or three secluded beaches in Mexico and Costa Rica, for several nights between August and November (scientists have not yet learned how to determine the exact time), hundreds of thousands of turtles come out of the sea and crawl along the beach. The lungs and dense skin preserved from their ancestors do not allow them to either suffocate or dry out, but the flippers are poorly adapted for movement on land. However, nothing can stop the turtles. They crawl and crawl until they reach the top of the beach where the vegetation begins. There they begin to dig nesting holes. There are so many of them that they climb on top of each other, looking for a suitable place. Vigorously digging flippers throw sand at their neighbors, touching their shells. But now the hole is ready. The turtle lays about a hundred eggs in it, carefully fills them with sand and returns to the sea. This goes on for three or four nights, during which time up to a hundred thousand ridleys can visit one beach. The development of the embryo lasts forty-eight days, but often before the expiration of this period, new hordes of turtles appear on the beach. Again the sand is strewn with crawling reptiles. They also begin to dig holes, and many quite by accident destroy the nests of their predecessors. Leathery shells and decaying embryos are scattered all around. Only one egg out of five hundred goes through the entire development cycle, and a young turtle is selected into the world. And this is still a very good ratio.

The factors driving this mass oviposition are not yet well established. It is possible that Ridleys visit such a small number of beaches in such numbers only because they are brought there by currents. On the other hand, if they spread their landfalls more evenly throughout the year, large permanent populations of predators such as crabs, snakes, iguanas and kites would be concentrated near their beaches. In the present state of affairs on these beaches, the rest of the time there is so little food that turtles almost do not meet such enemies there. If this is the case, then such mass character is bearing fruit: in both the Pacific and Atlantic oceans, ridleys remain one of the most common turtles, while the number of other species has declined markedly, and some are threatened with complete extinction.

The largest of them all, the leatherback turtle reaches a length of over two meters and weighs more than half a ton. It differs from all other turtles in that its shell is not horny, but made of hard, like rubber, skin with longitudinal ridges. She lives in the open sea and leads a solitary lifestyle. In tropical seas, the leatherback turtle is found everywhere, but it was also caught far in the south - in Argentina and in the north - off the coast of Norway. Nesting beaches of this species were found only a quarter of a century ago. Two were found: on the east coast of the Malay Peninsula and in South America - in Suriname. Both leatherback turtles are selected to lay eggs during the three-month season, several dozen individuals in one night.

Females usually appear in the dark at high tide when the moon rises. A dark hillock appears in the waves of the surf, gleaming in the moonlight. Leaning on huge flippers, the turtle gets out on wet sand. Every few minutes she stops to rest. It takes her at least half an hour to crawl to a sufficient height, since the nest must be out of reach of the waves, and on the other hand, you can only dig in wet sand that does not crumble. Often the female finds a suitable place only after two or three unsuccessful trials. But even then she works with great zeal: from under the front fins, the sand flies back. Soon the wide hole becomes deep enough. Then, with careful and precise movements of the hind flipper, the female digs a narrow vertical tunnel in its bottom.

To the sounds carried by the air, she is practically deaf, and human voices do not disturb her. But shine a flashlight on her while she crawls along the beach, and she can return to the sea without laying eggs. When the nest is ready, even the brightest light will not make the female stop laying. Pressing her hind flippers to the sides of the ovipositor, she quickly, group by group, directs the white balls of eggs into the tunnel, sighing heavily and moaning. Mucus oozes from her large, shiny eyes. Half an hour later, all the eggs are laid, and the female carefully fills the hole, crushing the sand with her hind flippers. She usually does not return to the sea immediately, but crawls along the beach, sometimes starting to dig, as if she is trying to confuse the trail. In any case, by the time the female heads for the water, the beach behind her is so dug up that it is almost impossible to recognize the nests.

However, people spying on her do not particularly need to guess. In Malaysia and Suriname, during the season, every night from dusk to morning, the beach is observed, and eggs are removed from the nest almost directly from under the laying female. Currently, a tiny fraction of these eggs are bought by government organizations in order to breed turtles in incubators, while the lion's share of them is sold in local markets and eaten.

It is possible that we do not yet know all the nesting beaches of the leatherback turtle. Perhaps some of these sea travelers come ashore on some uninhabited islands and lay eggs there that are not disturbed by man. They do not travel alone. The inhabitants of the littoral, which, having become adults, can no longer move away from shallow waters, at earlier stages of their development managed to travel in the form of seeds and larvae, eggs and juveniles. And for them, the island may not be a densely populated place where competition is as great as on their native coast, but a haven that offers them the freedom to evolve into completely new forms.

David Attenborough. LIVING PLANET. PUBLISHING HOUSE “MIR”. Moscow 1988

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At low tide, wide horizontal stripes of different colors can be seen on coastal stones and rocks. They form communities of living organisms. Lichens live in the upper, supralittoral zone, which is moistened only by splashes of waves, and blue-green algae usually settle near the high water level. Among the few animals living in this zone are some species of terrestrial insects and air-breathing littorinas, or shore snails.

Below is the littoral, or tidal, zone, which is either exposed or covered with water. The most characteristic crustaceans for it are sea acorns, which form a white strip on the stones, consisting of their shells. And the most common plant is fucus, bushy branched ribbon-like algae.

The most densely populated sublittoral zone, where stones are exposed only at low tide. In dense thickets of kelp and other algae, a variety of animals hide, including starfish, sea urchins and crustaceans. Behind this zone begins the kingdom of fish and other inhabitants of the open sea.

Life in the surf

One of the main problems that the animals face here is the waves continuously breaking on the rocky shore. There are two common ways to survive in such conditions: hide from the waves or hold on to the rocks as tightly as possible. Many animals find shelter under rocks or in crevices. Some sea urchins anchor themselves in cracks between rocks with their quills. Bivalve mollusks - petricola - and worms even drill holes in calcareous rocks and soft clay.

However, most of the inhabitants of the surf simply cling to the rocks. Seaweeds are held tightly by root-like processes. Sea acorns attach to stones, secreting a special secret that firmly sticks them to a wide variety of substrates. Mussels use a system of tiny cords. Ascidians, sponges and anemones also belong to numerous sedentary animals, permanently attached to one place. Saucers, snails, and other mollusks are held onto the rocks with the foot acting as a sucker.

mussels

Mussels live both in the middle and in the lowest zones, often forming large clusters - mussel banks. Each individual animal is attached to the surface of stones or underwater rocks with the help of many strong threads, consisting of a secret secreted by the byssus gland, which is located in the fleshy leg of the mussel. When in contact with water, the secret hardens. As a result, thin fibers are formed - byssus threads, they surprisingly firmly attach the mollusk to the stone.

Closely pressed to each other on banks, including artificial ones, mussels cannot change their position and remain in one place all the time. But a single mussel is still capable, stretching out its leg and straining enough, to break the threads, move to a new place and reattach there.

What happens at low tide?

Most fish and other animals that are able to move independently, at low tide, simply move away some distance from the coast, some of the inhabitants of the surf zone find temporary shelter in the water lingering in the depressions. Other animals wait out this short period in damp crevices where they are protected from direct sunlight. Many, in order to protect themselves from drying out, hide in water-soaked weaves of algae.

Mussels and sea acorns permanently attached to one place cannot hide. At low tide, they tightly close their shells, inside which there is little water, which makes it possible for them to avoid drying out. Saucers use a similar tactic. During high tide, these mollusks actively feed, scraping algae from the rocks with their rough, like sandpaper, tongues. At low tide, they each return to their place - in a small depression that they made in the stone. Pressing into this hole and clinging to its bottom with a muscular leg, they await the next tide.

Sea stars

Despite their English name, starfish, starfish are certainly not fish. They belong to the phylum Echinoderm, to which sea urchins also belong. Starfish do not swim, but crawl on hundreds of flexible tubular legs that protrude from grooves on the underside of their rays and end in suckers. With the help of these legs, starfish are attached to stones, and some species even open mollusk shells with them. A typical starfish has five rays, but some species have up to forty rays. If one of the beams breaks off, the star will not die, moreover, soon a new one will grow in place of the lost beam. Even more surprising is that if the beam came off along with a sufficiently large section of the central part of the star's body, then over time this beam turns into a full-fledged starfish.