Big animals with big horns. Strange, rare and unusual breeds of cows
On coastal cliffs, stones, shells on seabed you can see small white “houses” in the shape of a truncated cone, an acorn, and sometimes even a tulip. It was only recently possible to determine that their inhabitants are crustaceans.
Barnacles, which include balanus (balanus - acorn in Latin, which is why they are also called sea acorns), are the only group of free-living crustaceans that have refused independent travel in exchange for security behind the doors of a durable sink.
RAKING LEGS...
The calcareous shell of the balanus consists of several plates. Those that form the walls are firmly attached, and two or four plates - “house doors” - are movable. Under favorable conditions, they are open, and the rowing thoracic legs of the crustacean, covered with long bristles, rhythmically emerge from the hole. In case of danger, the valves of the lids close so tightly that the crustacean is able to remain alive for several months. fresh water or even in a dry state, so they can also settle in the littoral zone - in the ebb and flow zone. The balanus, which looks very little like a crustacean, is located inside the shell on the back, with the front part of its head bent under the body, the back part enlarged, and the mouth directed upward. From the water driven into the shell by its pectoral legs, the crustacean captures oxygen, animal and plant plankton, as well as detritus particles - dead organic matter.
IN CROWDED BUT NOT MAD
Sea acorns prefer to settle in colonies, which is more profitable in many respects. It has been established that crustaceans in colonies row their legs in one direction, which creates a fairly strong current of water, carrying food for the entire colony. Crustaceans living “in a community” also receive an advantage during reproduction. They are hermaphrodites, but close proximity gives them the opportunity for cross-fertilization. Fertilized eggs are stored for some time in the cavity of the shell, covered with a common chitinous shell. With the coming favorable conditions- increase in water temperature and appearance of food ( planktonic algae) - eggs hatch into free-swimming larvae, typical of crustaceans - nauplii. They are easily recognized by their side “ears” or “horns”. In spring, Balanus larvae make up a significant part of the plankton and serve as food for the young of many fish. After several molts, the nauplii turns into a larva with a bivalve shell called cypris. She no longer feeds, but is looking for a place to settle. It has been established that adult balanus emit special substances into the water that attract larvae, and they settle “among their own,” increasing the density of the colony. They attach to the substrate with short anterior antennae containing cement glands, shed their larval shell and begin to build a strong limestone house around themselves. After three months, young balanuses can reproduce on their own.
STOWER PASSENGERS
Despite their sedentary lifestyle, barnacles can travel. Their larvae settle on the shells of large crabs, mollusk shells, whale skins or underwater parts of ships. With their help, crustaceans travel long distances, withstanding prolonged desalination when ships cross rivers. A dense and heavy “fur coat” of balanus shells on the bottom of the vessel reduces its speed, impairs maneuverability and leads to additional fuel consumption. For a year of sailing on each square meter the bottom increases to 10 kilograms of balanus. Therefore, sailors have been fighting fouling for a long time, using various methods: mechanical (scraping shells from the bottom), physical (destructing them with ultrasound), chemical (using toxic paints when painting a ship).
BALANUS IN HISTORY
Some historians believe that sea acorns were partly to blame for the defeat of the Russian squadron in Battle of Tsushima 1905. Having made a long voyage from the Baltic to the Pacific Ocean, Russian warships, overgrown with colonies of balanuses, noticeably lost speed, which negatively affected their combat effectiveness.
About 60 species are known in the world sea acorns, majority - small sizes. The largest is the giant sea acorn, reaching 20 centimeters. Different types Balanus are found from the upper littoral zone to depths of over 6000 meters. The small crustacean Balanus improv¡sus (the diameter of the house is about 10 millimeters) was brought to the Baltic on the bottoms of ships from North America and has spread widely there, which is not surprising, because it easily tolerates sudden changes in environmental conditions, including overheating, freezing into ice, drying out and desalination.
Interesting Facts
The cement that holds the balanus on the substrate is very strong and can withstand temperatures above 200°C. It is not absorbed by strong acids, alkalis, or organic solvents.
Charles Darwin long years studied these unusual animals and dedicated a 4-volume monograph “Cirripedas” to them.
Due to the presence of a shell, these animals were previously classified as mollusks.
a brief description of
Type: arthropods
Class: crustaceans
Squad: barnacles
Genus: sea acorn, balanus
View: unexpected balanus
Latin name: Balanus improv¡sus
Size: about 10 mm
Shell color: grayish white
Lifespan sea acorn:
from 2 to 7 years
Incredible facts
Men are often concerned about whether their manhood is of adequate length and width, whether it will satisfy a woman, and most importantly, whether size matters.
And although many representatives of the stronger sex would like to have an even more impressive penis size, it would be difficult for them to compare with the organs of some animals.
Animal genitals: the largest penises
Here are 7 animals with the most large sizes penises relative to body size
Blue whale
The blue whale boasts the largest penis on Earth. The average size penis blue whale ranges from 2.4 to 3 meters. The exact size is difficult to determine, since the size of the erect penis of a blue whale can only be observed during copulation.
However, relative to the size of its body, the blue whale's enormous penis is fairly average. The blue whale's penis-to-body length ratio is 1:10, while the average male ratio is 1:12.
Ostracod Colymbosathon ecplecticos
It's small ancient creature has such a large penis that even its Greek name Colymbosathon ecplecticos translates to "amazing swimmer with a big dick." When archaeologists discovered fossils of this creature in 2003, they were quite surprised by its manhood.
The ratio of the length of the penis to his body was 1:5. Translated into a human, this ratio would mean a penis size of about 38 cm. In addition, the creature had very long sperm – about 1 cm, while the size of the creature itself did not exceed 5 mm.
African elephant
Penis size African elephant reaches up to 2 meters. The ratio of penis to body size of this mammal with great dignity is 1:4 or about 45 cm in humans.
Deep sea squid Onykia ingens
These squids live at a depth of 3000 meters, and the size of their genital organ reaches almost the length of its body. The ratio of penis length to body units is 1:1. And one caught 38-centimeter squid was observed to have an erection in which penis size reached 67 cm.
banana slug
Banana slugs reach about 25 cm in length, with a penis to body ratio of 1:1, which means that the length of their dignity is almost the same as that of a person.
Moreover, banana slugs are hermaphrodites. Each of them has a penis located on the side of the head, with the help of which they can impregnate each other and become pregnant.
Argentine duck
Although ducks are not known for having large penises, there is one member of the duck family whose penis size is larger than that of any vertebrate on the planet. The Argentine duck boasts a penis that is twice as long as the bird's body. The average size of the bird is about 20 cm, while the length of the penis reaches 42.5 cm.
How does this animal move with such a large organ? The whole point is that the male dignity of the duck has spiral view. Moreover, females have a long, spiral-shaped vagina that curls in the opposite direction, helping her prevent fertilization, as males tend to forcefully copulate.
sea acorn
These sessile crustaceans can change the size of their genitals depending on their environment. They have the most big penises relative to their body size, reaching ratio 40:1. Because most the time they spend on the stone, they grow a long penis to increase the chances of fertilization.
Suborder Armored - Thoracica
G. B. Zevina
Crustaceans highly modified due to their attached lifestyle. The body is hidden in a limestone house, consisting of individual plates - tablets. The tablets are distinguished by the surface of the skin "masonry" - a mantle that covers the entire body of the animal. Some of the tablets are motionlessly connected to each other and form the walls of the house (Fig. 66, A), others form its lid and can close and open (Fig. 67). Through the gap between the movable signs the animal communicates with external environment. At the bottom of the house, dorsal side down, lies a crustacean. Head with oral appendages; thoracic section of 6 segments, each of which bears a pair of two-branched limbs - cirriples; the abdomen is underdeveloped. The antennules and the entire anterior section of the head are transformed into an organ of attachment: in sea ducks (superfamily Lepadomorpha) - into an elongated fleshy stalk (Fig. 66, B), in others (superfamilies Balanomorpha and Verrucomorpha) - into a flat, wide sole. Mostly hermaphrodites. Some species have dwarf males sitting in the mantle cavity of females or hermaphrodites. Fertilization is internal. A free-swimming larva emerges from the egg - a nauplius, which, after molting several times, turns into a cyprisoid larva, characteristic only of barnacles.
They live in all seas and oceans from the littoral zone to a depth of 7000 m.
Family Barnacles - Lepadidae
Barnacle- Lepas anatifera (L.) (Fig. 66, B). The head has 5 thin limestone tablets and a rather long stem. The plates are smooth. Karina forms a forked extension at the bottom. The left scutum bears on inside umbilical tooth (the umbilicus is the center of growth of each tablet). Adult specimens have 2 (sometimes 1) thread-like appendages on the body. Head length up to 5, stalk up to 60 cm, usually much less.
Found in tropical, subtropical and temperate regions of the World Ocean. Leads a passive-pelagic lifestyle. Sometimes it is carried into the Sea of Japan on drifting objects and on the bottoms of ships.
Family Sea acorns - Balanidae
Triangular sea acorn- Balanus trigonus Darwin (Fig. 68). The house is conical, usually flattened, ribbed, and colored pink or reddish-purple. The radii are lighter, sometimes white. The scutum is narrow, externally with 1-4 rows of deep openings, with a long articular ridge, a narrow and deep articular groove, and a short ridge of the adductor (locking muscle). Tergum wider than scutum, with a wide short spur. The side plates are pierced by longitudinal channels without transverse partitions, but at the top the channels are filled again. The diameter of the base of the house is up to 25 mm.
Widely distributed in tropical and subtropical waters. In 1970 it was discovered in the fouling of buoys in the bay. Peter the Great. Often found in fouling of ships sailing in tropical and subtropical waters.
Amphitrite sea acorn- Balanus araphitrite amphitrite Darwin (Fig. 69). The house is conical, with longitudinal brown-violet stripes; the operculum valves are also partially painted. Scutum with well-developed articular crest reaching the middle of the tergal margin. Tergum with relatively wide spur and straight lower margin. The diameter of the base of the house is up to 16, height is up to 9 mm.
Widely distributed in tropical and subtropical waters. Lives in the sublittoral zone. To the hall. Peter the Great is overgrown with the bottoms of ships and hydraulic structures.
sea acorn Ivory - Balanus eburneus Gould (Fig. 70). The house is yellowish in color, conical, sometimes with convex walls, in adult specimens with rather thick plates. The radii are wide with obliquely cut tops. The plaques and the limestone base of the house are pierced by channels with transverse partitions. Scutum externally with well-defined growth lines and radial striations. Tergum with strongly concave lower margin on the carinal side and with a rather wide spur. The diameter and height of the house is up to 30 mm. Widely distributed on the bottoms of ships in tropical, subtropical and even boreal waters. To the hall. Peter the Great was first recorded in 1969. The species is thermophilic, predominantly brackish-water.
Unusual sea acorn- Balanus improvisus Darwin (Fig. 71). House white, conical or hemispherical-conical, with very convex smooth walls, in crowded settlements, cylindrical. The radii are narrow, with rounded beveled tops. The wings are wide. The signs and the limestone base of the house are pierced by channels with partitions. The scutum has well-developed growth lines on the outside, but without radial striations; on the inside, it has a well-developed articular ridge and a long, almost straight adductor ridge. The lower edge of the tergum is straight or almost straight, the spur is rather narrow. The diameter and height of the house is up to 23 mm.
Behind last decades on the bottoms of ships has become widespread throughout the world. U Japanese Islands discovered in 1962, in the hall. Peter the Great - in 1969. Lives in the sublittoral zone. The species is predominantly brackish-water, although it can live at salinities from 2 to 60%o, and tolerates pollution well.
Beaked sea acorn- Balanus rostratus Hoek (Fig. 72). The house is light, grayish, smooth, sometimes folded. The carinolateral plates are narrow. The base is calcareous, thin, radially striated. The scutum has a low articular crest, a narrow articular groove, a low adductor crest and a deep depressor muscle fossa. Tergum with beak-shaped, uncolored apex. Externally with clearly visible growth ridges and weak radial striations. The spur is short, wide at the base and tapering towards the end, its lower edge is slightly beveled. The side signs of the house are ribbed from the inside. Channels inside the plates with transverse partitions, at least in the upper parts of the plates. House diameter up to 85, height up to 60 mm.
Distributed in the Yellow Sea, Sea of Japan, east coast Japanese Islands, in the Sea of Okhotsk, Bering Sea and along the Pacific coast of North America south to British Columbia. Lives in the sublittoral zone, sometimes found in fouling of ships and hydraulic structures.
Jagged sea acorn- Balanus crenatus Bruguiere (Fig. 73). The house is white or gray, smooth or with external folds, with a jagged upper edge. The radii are narrow, the wings are wide. The inside plates are ribbed; channels inside plates with transverse partitions. Scutum with strongly projecting articular crest; the adductor imprint is present, but the adductor ridge is not present. Tergum with short wide spur. The diameter of the base of the house is up to 40 mm. With severe crowding, the houses take on an elongated tubular shape.
Distributed in the northern part Atlantic Ocean, in all marginal seas Arctic Ocean, Bering, Okhotsk and Japan seas. Along the Pacific coast of North America it reaches San Francisco. Lives in the sublittoral zone. Common in fouling. To the hall. Peter the Great is common from the water's edge and deeper.
Ribbed sea acorn- Balanus cariosus (Pallas) (Fig. 74). The house is off-white in color, often conical; in crowded settlements it can be cylindrical or lily-shaped. The outside is covered with rows of narrow ribs resembling a thatched roof. The house signs are thick, pierced by thin channels arranged in several rows with transverse partitions. Sometimes the channels are filled a second time. The lid doors are deeply immersed inside the house. Scutum with a small articular crest; the adductor crest "is usually well developed; the imprint of the depressor muscle is deep and wide. The tergum is narrow, with a long spur tapering towards the end, usually with a sharp beak-shaped apex of purple color (as a result of corrosion, the apex can be rounded and short). The diameter of the base of the house is up to 50 , height y cylindrical shapes up to 100 mm.
Distributed in the northern part Pacific Ocean from the northern part of the Korean Peninsula to Bering Sea and along the American coast south to Oregon. Lives in the littoral zone. To the hall. Peter the Great settles under the cover of various ledges, in crevices on the side of the rocks facing the shore.
Common sea acorn- Balanus balanoides (L.) (Fig. 75). The house is grayish in color, conical, tubular or lily-shaped, smooth or folded. The radii are narrow. The base is membranous. The channels piercing the tablets are thin, usually secondarily filled. "The scutum has a well-developed articular crest, reaching the middle of the tergal margin; the imprints of the adductor and depressor muscles are clearly visible. The tergum has a short and rather wide spur, with a powerful triangular articular crest; the crests are clearly visible on the depressor imprint. The diameter of the base of the house is up to 20, the height up to 22 mm.
Distributed in the North Atlantic, Barents, White and all Far Eastern seas. Littoral species, sometimes extending into the sublittoral. To the hall. Peter the Great is found mainly in the formations of vessels.
Giant sea acorn- Balanus evermanni Pilsbry (Fig. 76). The house is conical and very large. The plates are loosely connected, thick, narrow (especially the carinolateral ones), strongly tapering upward. The wings are wide, the radii are narrow. The hole is usually wide, deep, jagged. Tergum with a sharp curved apex and a narrow spur. The base of the house in adult individuals is calcareous, in juveniles it is membranous or calcareous, but very thin. The diameter of the base of the bottom of the house is up to 100, height is up to 200 mm.
Distributed in the Bering, Okhotsk and northwestern parts Sea of Japan at depths from 50 to 500 m, mainly in places with strong bottom currents. Often forms huge clumps. To the hall. Peter the Great has not yet been discovered.
Giant muscle fibers in the adductor and depressor muscles can be used by physiologists and histologists for special scientific research. Meat can be eaten.
Chthamalidae family - Chthamalidae
Htamalyus Dolla- Chthamalus dalli Pilsbry (Fig. 77). The house is low, conical, sometimes cylindrical, folded, gray or grayish-brown. Like other representatives of the genus Chthamalus, the rostrum is winged. There are 6 side plates (like balanuses). The base of the house is webbed. The scutum is elongated, with well-developed adductor ridges, with several ridges on the depressor imprint. The tergum is wide, with a very short, almost imperceptible spur, and a wide articular ridge. The diameter of the base of the house is up to 9.5, height is up to 7 mm.
Distributed from the northern part of the Yellow Sea to the Bering Sea and along the American coast from Unalaska to Washington State. Inhabits rocks in the upper horizon of the littoral zone.
Those who want to see these peculiar animals just need to come to the seashore: coastal stones, rocks, shells are strewn with their small conical houses. Sea acorns, or, as they are also called, balanuses, belong to the order barnacles, although according to appearance they are not at all similar to the crustaceans known to us.
The barnacles, which include the sea acorn, are remarkable in many respects and do not look like crayfish.
As adults, they lead a sedentary lifestyle, attaching themselves to all sorts of underwater objects - rocks, rocks, piles, and the bottoms of ships. The body of the barnacles is enclosed in a hard limestone house, consisting of individual plates. Some of these plates are movably connected to each other, so the crustacean can push the plates apart and insert the thoracic legs into the resulting gap from time to time, making characteristic movements. At the same time, water with planktonic organisms is driven inside the house. This is how nutrition and breathing are carried out.
The presence of a hard shell and a sedentary lifestyle have long forced scientists to classify these animals as mollusks. Only by discovering a barnacle larva, similar in structure to other crustaceans, did scientists determine whether these animals belonged to the class of crustaceans.
“As long as you live your time, a lot of all sorts of dirty shells stick to our sides” - Mayakovsky used this metaphor when comparing human life with the life of the ship. And indeed, imagine that a newly built ship leaves the harbor and begins sailing. Its speed is known, it fits well into the schedule. However, the movement is slowing down every day. More and more time and fuel are spent covering the same route. Why is this happening? The bottom of the ship is overgrown with various marine animals, forming thick layers, as a result, friction with the water increases and speed decreases.
The basis of fouling on ships is made up of barnacle crustaceans - sea acorns.
They settle not only on ships. They are strewn with coastal rocks and stones, they attach to shells of mollusks, to the shells of crabs, settle on the skin of whales, on whalebone and even on the teeth of sperm whales, on the sides of fish and other most incredible objects stranded underwater. Sea acorns look like a small white cup consisting of several “petals”. Inside the calyx, a cone of several valves is visible, shaped like a tooth. The valves of this tooth are capable of opening, and the legs of the crustacean protrude through the resulting hole.
At the bottom of such a house, securely closed with very hard doors, the crustacean itself lies on its back. The front of his head is tucked under the body so that the antennae are in the middle of the “sole.” The back of the head is enlarged, so the acorn's mouth faces upward. The crustacean, sticking its legs covered with long bristles out of the house, straightens them like a fan, and then folds them. These movements create a flow of water directed inside the house.
The food of sea acorns is quite varied due to the fact that the legs are covered with bristles of varying thickness: they sit more often on the front legs, and less often on the hind legs. As a result, different legs filter out particles different sizes. Sea acorns eat algae, bacteria, and many other small planktonic creatures, most notably their relatives, copepods. They also swallow their own larvae, but the adult larvae of sea acorns are not digested by their parents and come out unharmed.
Since the crustacean has all its adult life spends inside the house, he does not need well-developed senses, but some of them remain. Sea acorns are able to distinguish light from darkness with the help of a single primitive eye. Of course, crustaceans don’t care at all whether it’s day or night, and that’s not why they preserved the eye. With its help, acorns react to instantaneous changes in illumination, i.e. notice a shadow falling on their shell, but it could also be from a predator. Just in case, they quickly retract their legs and close the doors of the house. If you shade the shell of an acorn with a constant frequency for a long time, the crustacean stops reacting to this stimulus; it gets used to the fact that the shadow does not indicate danger. Among sea acorns there are species in which addiction occurs at different intervals. The more “fearful” crustaceans do not “believe” for a very long time that they are not in danger, while the more “brave” ones quickly get used to not reacting to shading.
In nature, sea acorns orient their houses so that the entrance to it is directed towards the light. If the larvae settle unsuccessfully, the crustacean is able, at the very beginning of its sessile life, to slightly turn the house so that the light falls directly into its “window”. This, however, does not limit the requirements of sea acorns when choosing the position of the house. They try to place their home so that the entrance is directed towards the currents. Then the constant flow of water brings in more food particles. Some acorns are so “lazy” that they generally stop waving their legs to force water into the sink, but sit motionless, hanging their bristly legs like a net towards the current.
Most species of sea acorns are bisexual organisms, but self-fertilization is not common among them. The crustaceans manage to mate without leaving home, with one individual acting as a male and the other as a female. Such marriages are possible only in settlements where acorn houses are closely adjacent to each other. The copulatory organ of sea acorns is very long and is able to reach the neighboring house to transfer sperm there. Crustaceans living completely alone are capable of self-fertilization. Fertilized eggs are covered in a common chitinous shell and stored in the cavity of the house.
Sea acorns spend their early childhood in much the same way as their relatives - other crayfish. Having hatched from the egg, the larva leads a free lifestyle, molts several times and turns into a larva with a bivalve shell. It is always slightly open, and the legs of the crustacean stick out from it, with the help of which it swims. After some time, the larva settles and takes up permanent residence, attaching to the substrate with its short anterior antennae. Reliability of attachment is ensured by the adhesive secretion of cement glands. The larva sheds its temporary bivalve shell and begins to build a reliable, durable home around itself.
Those who want to see these peculiar animals just need to come to the seashore: coastal stones, rocks, shells are strewn with their small conical houses. Sea acorns, or, as they are also called, balanuses, belong to the order of barnacles, although in appearance they are not at all similar to the crustaceans known to us.
The barnacles, which include the sea acorn, are remarkable in many respects and do not look like crayfish.
As adults, they lead a sedentary lifestyle, attaching themselves to all sorts of underwater objects - rocks, stones, piles, and the bottoms of ships. The body of the barnacles is enclosed in a hard limestone house, consisting of individual plates. Some of these plates are movably connected to each other, so the crustacean can push the plates apart and insert the thoracic legs into the resulting gap from time to time, making characteristic movements. At the same time, water with planktonic organisms is driven inside the house. This is how nutrition and breathing are carried out.
The presence of a hard shell and a sedentary lifestyle have long forced scientists to classify these animals as mollusks. Only by discovering a barnacle larva, similar in structure to other crustaceans, did scientists determine whether these animals belonged to the class of crustaceans.
“As long as you live your life, a lot of all sorts of dirty shells stick to our sides” - this was the metaphor used by Mayakovsky, comparing human life with the life of a ship. And indeed, imagine that a newly built ship leaves the harbor and begins sailing. Its speed is known, it fits well into the schedule. However, the movement is slowing down every day. More and more time and fuel are spent covering the same route. Why is this happening? The bottom of the ship is overgrown with various marine animals, forming thick layers, as a result, friction with the water increases and speed decreases.
The basis of fouling on ships is made up of barnacle crustaceans - sea acorns.
They settle not only on ships. Coastal rocks and stones are strewn with them, they attach to mollusk shells, to crab shells, settle on the skin of whales, on whalebone and even on the teeth of sperm whales, on the sides of fish and other most incredible objects found under water. Sea acorns look like a small white cup consisting of several “petals”. Inside the calyx, a cone of several valves is visible, shaped like a tooth. The valves of this tooth are capable of opening, and the legs of the crustacean protrude through the resulting hole.
At the bottom of such a house, securely closed with very hard doors, the crustacean itself lies on its back. The front of his head is tucked under the body so that the antennae are in the middle of the “sole.” The back of the head is enlarged, so the acorn's mouth faces upward. The crustacean, sticking its legs covered with long bristles out of the house, straightens them like a fan, and then folds them. These movements create a flow of water directed inside the house.
The food of sea acorns is quite varied due to the fact that the legs are covered with bristles of varying thickness: they sit more often on the front legs, and less often on the hind legs. As a result, different legs filter out particles of different sizes. Sea acorns eat algae, bacteria, and many other small planktonic creatures, most notably their relatives, the copepods. They also swallow their own larvae, but the adult larvae of sea acorns are not digested by their parents and come out unharmed.
Since the crustacean spends its entire adult life inside the house, it does not need well-developed sense organs, but some of them remain. Sea acorns are able to distinguish light from darkness with the help of a single primitive eye. Of course, crustaceans don’t care at all whether it’s day or night, and that’s not why they preserved their peephole. With its help, acorns react to instantaneous changes in illumination, i.e. notice a shadow falling on their shell, but it could also be from a predator. Just in case, they quickly retract their legs and close the doors of the house. If you shade the shell of an acorn with a constant frequency for a long time, the crustacean stops reacting to this stimulus; it gets used to the fact that the shadow does not indicate danger. Among sea acorns there are species in which addiction occurs at different intervals. The more “fearful” crustaceans do not “believe” for a very long time that they are not in danger, while the more “brave” ones quickly get used to not reacting to shading.
In nature, sea acorns orient their houses so that the entrance to it is directed towards the light. If the larvae settle unsuccessfully, the crustacean is able, at the very beginning of its sessile life, to slightly turn the house so that the light falls directly into its “window”. This, however, does not limit the requirements of sea acorns when choosing the position of the house. They try to place their home so that the entrance is directed towards the currents. Then the constant flow of water brings in more food particles. Some acorns are so “lazy” that they generally stop waving their legs to force water into the sink, but sit motionless, hanging their bristly legs like a net towards the current.
Most species of sea acorns are bisexual organisms, but self-fertilization is not common among them. The crustaceans manage to mate without leaving home, with one individual acting as a male and the other as a female. Such marriages are possible only in settlements where acorn houses are closely adjacent to each other. The copulatory organ of sea acorns is very long and is able to reach the neighboring house to transfer sperm there. Crustaceans living completely alone are capable of self-fertilization. Fertilized eggs are covered in a common chitinous shell and stored in the cavity of the house.
Sea acorns spend their early childhood in much the same way as their relatives - other crayfish. Having hatched from the egg, the larva leads a free lifestyle, molts several times and turns into a larva with a bivalve shell. It is always slightly open, and the legs of the crustacean stick out from it, with the help of which it swims. After some time, the larva settles and takes up permanent residence, attaching to the substrate with its short anterior antennae. Reliability of attachment is ensured by the adhesive secretion of cement glands. The larva sheds its temporary bivalve shell and begins to build a reliable, durable home around itself.