CATDOLL : CATDOLL: How sea cucumbers grow, the specific process.

The individual development process of sea cucumbers is divided into the planktonic larval stage and the benthic growth stage, with a metamorphosis process between the two developmental stages.

1. Fertilization Fertilization is the union of male and female reproductive cells, from the entry of sperm into the egg until the complete assimilation of the female reproductive cells. Most sea cucumber eggs are fertilized and develop in the water after they are laid.

2. Cleavage: After the egg is fertilized, it begins to develop. First, the single-cell fertilized egg undergoes a series of complex divisions to form a multi-cellular embryo. This process is called cleavage.

3. Blastocyst stage The fertilized egg of sea cucumber undergoes multiple divisions to form a hollow blastocyst and enter the blastocyst stage. The blastocyst is the result of cleavage. It is a multicellular embryo formed by a single-cell fertilized egg through a series of repeated divisions. Its appearance is like a mulberry and is called secondary division (there are 512 blastomeres). The embryo enters the blastocyst stage. A large and round cavity appears in the center, which is called the blastocyst cavity.

4. Gastrula stage: As the embryo grows, by the late blastocyst stage the entire embryo moves and the vegetal pole gradually elongates, and a double-germ layer embryo appears and enters the gastrula stage. The embryo enters the gastrula stage after 24-28 hours.

5. Auricularia The larvae that continue to develop from the gastrula stage look like human ears from the side, so they are called auricularia. The embryo develops to the auricularia stage after 2-48 hours.

6. Bottle-shaped larvae Bottle-shaped larvae are the beginning of the metamorphosis of sea cucumber larvae. As the ear-shaped larvae further develop, the dorsal and ventral shape of the larvae gradually changes into a barrel shape, which is very similar to a sea cucumber, so it is called a bottle-shaped larvae.

7. The five-tentacle larva is also called the five-arm larva. As the barrel-shaped larva develops, the cilia of the ciliary ring gradually disappear, the frontal area shrinks, the mouth moves almost to the front end, and the five tentacles extend out of the vestibule and can retract freely, so it is called the five-tentacle larva.

8. When the juvenile sea cucumber becomes a juvenile sea cucumber, the metamorphosis of the juvenile sea cucumber ends. In the late stage of the five-tentacle juvenile sea cucumber, the juvenile sea cucumber basically forms the prototype of the sea cucumber in terms of morphology. The juvenile sea cucumber begins to elongate and forms some honeycomb-like calcium bone plates on the body surface.

Additional information:

During the growth of sea cucumbers, suitable water quality indicators such as temperature, salinity, pH, dissolved oxygen, etc. will have an impact on them.

1. Temperature: The most suitable temperature for the growth of Donggao sea cucumbers is 10-18 degrees. When it is higher than 24 degrees, it begins to enter summer dormancy, and when it is lower than 5 degrees, it begins to enter winter dormancy. The water temperature of the sea cucumber pond is generally stable, and neither temperature drop nor temperature rise has a big impact. However, when changing the water when the weather changes drastically, it is necessary to measure the temperature difference.

2. Salinity: The most suitable salinity for the growth of sea cucumbers is 27-30. The salinity in which they can survive is not more than 39 and not less than 14. Changes in salinity have a great impact on sea cucumbers, and unstable salinity is often encountered in daily management.

For example, when it rains heavily in summer, you must measure the salinity of the open sea before changing the water. If the difference is less than 2, you can change the water. If it is more than 2, change the water as little as possible, otherwise the sea cucumber will easily vomit intestines.

3. PH: The most suitable PH for the growth of sea cucumbers is between 7.5-8.5. A low PH value means low dissolved oxygen in the water, high carbon dioxide content, and bacteria will multiply in large numbers. If the PH is high, toxic ammonia will be high, which will harm the sea cucumbers. The PH of outer-ring sea cucumbers is generally stable.

4. Dissolved oxygen: The dissolved oxygen of sea cucumbers cultured in outdoor ponds is a very important indicator, because the size of its deviation directly affects the yield of sea cucumbers and determines the survival of sea cucumbers. Generally, the dissolved oxygen level can be around 6. If it is lower than 4, it will greatly inhibit the growth of sea cucumbers.

At the same time, some harmful substances in the water will breed in large quantities, so it is recommended to add oxygen regularly and in advance according to the situation of the pond. It is best to lay oxygenation pipes or install aerators, which can greatly improve the daily hypoxia problem.

Reference source: Baidu Encyclopedia - Sea Cucumber

There are two ways of reproduction of sea cucumbers, one is asexual reproduction and the other is sexual reproduction.

Asexually reproducing sea cucumbers have the ability to self-cut. During the breeding season, they will cut their bodies into two or more parts. After a period of time, the fragments with the cloaca will grow back into sea cucumbers.

The sexual reproduction of sea cucumbers is through the combination of sperm and eggs to form embryos, which then hatch into larvae. Most sea cucumbers are dioecious, but some species are hermaphroditic.

Sea cucumbers with different sexes reproduce outside the body. During the breeding season, the male sea cucumbers first discharge semen from their genital openings before the female sea cucumbers begin to lay eggs. The eggs and sperm combine in the water to form embryos, which hatch into larvae in the water.

The reproduction of hermaphroditic sea cucumbers is internal fertilization and external reproduction. The eggs of hermaphrodites are first fertilized in the cloaca, then discharged into the water, where they hatch into larvae.

Additional information:

The appearance characteristics of sea cucumber:

The body is cylindrical, 10 to 20 cm long, and the largest can reach 30 cm. It is dark in color and has many fleshy thorns.

The tentacles are wheel-shaped, with 17 to 30 in number, usually 20 in number.

The tentacles and hand capsules are well developed. Sea cucumbers have been bred on Earth earlier than primitive fish, and have existed since the Precambrian period more than 600 million years ago. They are the earliest living species and are known as living fossils of the ocean. They have survived several major destructions of the Earth and have witnessed the changes of the Earth several times. The mouth is at the front, mostly on the ventral side. The anus is at the back, mostly on the dorsal side.

There are usually tube feet on the back and tube feet on the ventral side. The internal skeleton is degenerate into tiny bone plates. Many species have 5 rows of tube feet from mouth to anus. The anus is used for both breathing and excretion of waste. There are 10 or more retractable tentacles around the mouth, which are used for hunting or burrowing. Many species can release internal organs from the anus and then regenerate new ones, probably to escape from enemies.

The cloaca often contains symbiotic fish of the genus Carapus, many of which can release toxins that are lethal to small animals but are not life-threatening to humans.

Reference source: Baidu Encyclopedia - Sea Cucumber

There are two ways of reproduction of sea cucumbers, one is asexual reproduction and the other is sexual reproduction.

Asexually reproducing sea cucumbers have the ability to self-cut. During the breeding season, they will cut their bodies into two or more parts. After a period of time, the fragments with the cloaca will grow back into sea cucumbers.

The sexual reproduction of sea cucumbers is through the combination of sperm and eggs to form embryos, which then hatch into larvae. Most sea cucumbers are dioecious, but some species are hermaphroditic.

Sea cucumbers with different sexes reproduce in vitro. During the breeding season, the male sea cucumber discharges semen from the genital pore before the female sea cucumber begins to lay eggs. The eggs and sperm combine in the water, forming embryos that hatch into larvae in the water.

The reproduction of hermaphroditic sea cucumbers is internal fertilization and external reproduction. The eggs of hermaphrodites are first fertilized in the cloaca, then discharged into the water, where they hatch into larvae.

Additional information:

During the growth of sea cucumbers, suitable water quality indicators such as temperature, salinity, pH, dissolved oxygen, etc. will have an impact on them.

1. Temperature: The most suitable temperature for sea cucumber growth is 10-18 degrees. When it is higher than 24 degrees, it will enter summer dormancy, and when it is lower than 5 degrees, it will enter winter dormancy. The water temperature of the sea cucumber pond is generally stable, and neither temperature drop nor temperature rise has a big impact. However, when the weather changes drastically, you must measure the temperature difference when changing the water.

2. Salinity: The most suitable salinity for the growth of sea cucumbers is 27-30. The salinity in which they can survive is not more than 39 and not less than 14. Changes in salinity have a great impact on sea cucumbers, and unstable salinity is often encountered in daily management.

For example, when it rains heavily in summer, you must measure the salinity of the open sea before changing the water. If the difference is less than 2, you can change the water. If it is more than 2, change the water as little as possible, otherwise the sea cucumber will easily vomit intestines.

3. PH: The most suitable PH for the growth of sea cucumbers is between 7.5-8.5. A low PH value means low dissolved oxygen in the water, high carbon dioxide content, and bacteria will multiply in large numbers. If the PH is high, toxic ammonia will be high, which will harm the sea cucumbers. The PH of outer-ring sea cucumbers is generally stable.

4. Dissolved oxygen: The dissolved oxygen of sea cucumbers cultured in outdoor ponds is a very important indicator, because the size of its deviation directly affects the yield of sea cucumbers and determines the survival of sea cucumbers. Generally, the dissolved oxygen level can be around 6. If it is lower than 4, it will greatly inhibit the growth of sea cucumbers.

At the same time, some harmful substances in the water will breed in large quantities, so it is recommended to add oxygen regularly and in advance according to the situation of the pond. It is best to lay oxygenation pipes or install aerators, which can greatly improve the daily hypoxia problem.

Reference source: Baidu Encyclopedia - Sea Cucumber

The growth process of sea cucumber:

The individual development process of sea cucumbers is divided into the planktonic larval stage and the benthic growth stage, with a metamorphosis process between the two developmental stages.

1. Fertilization Fertilization is the union of male and female reproductive cells, from the entry of sperm into the egg until the complete assimilation of the female reproductive cells. Most sea cucumber eggs are fertilized and develop in the water after they are laid.

2. Cleavage: After the egg is fertilized, it begins to develop. First, the single-cell fertilized egg undergoes a series of complex divisions to form a multi-cellular embryo. This process is called cleavage.

3. Blastocyst stage The fertilized egg of sea cucumber undergoes multiple divisions to form a hollow blastocyst and enter the blastocyst stage. The blastocyst is the result of cleavage. It is a multicellular embryo formed by a single-cell fertilized egg through a series of repeated divisions. Its appearance is like a mulberry and is called secondary division (there are 512 blastomeres). The embryo enters the blastocyst stage. A large and round cavity appears in the center, which is called the blastocyst cavity.

4. Gastrula stage: As the embryo grows, the entire embryo moves and the vegetal pole gradually elongates in the late blastocyst stage, and a double-germ layer embryo enters the gastrula stage. The embryo enters the gastrula stage after 24≈28 hours.

5. Auricularia The larvae that continue to develop from the gastrula stage look like human ears from the side, so they are called auricularia. The embryo develops to the auricularia stage after 2-48 hours.

6. Bottle-shaped larvae Bottle-shaped larvae are the beginning of the metamorphosis of sea cucumber larvae. As the ear-shaped larvae further develop, the dorsal and ventral shape of the larvae gradually changes into a barrel shape, which is very similar to a sea cucumber, so it is called a bottle-shaped larvae.

7. The five-tentacle larva is also called the five-arm larva. As the barrel-shaped larva develops, the cilia of the ciliary ring gradually disappear, the frontal area shrinks, the mouth moves almost to the front end, and the five tentacles extend out of the vestibule and can retract freely, so it is called the five-tentacle larva.

8. When the juvenile sea cucumber becomes a juvenile sea cucumber, the metamorphosis of the juvenile is over. In the late stage of the five-tentacle juvenile, the juvenile basically forms the prototype of the sea cucumber in terms of morphology. The juvenile begins to elongate and forms some honeycomb-like calcium bone pieces on the body surface.

Additional information:

The appearance characteristics of sea cucumber:

The body is cylindrical, 10 to 20 cm long, and the largest can reach 30 cm. It is dark in color and has many fleshy thorns.

The tentacles are wheel-shaped, with 17 to 30 in number, usually 20 in number.

The tentacles and hand capsules are well developed. Sea cucumbers have been bred on Earth earlier than primitive fish, and have existed since the Precambrian period more than 600 million years ago. They are the earliest living species and are known as living fossils of the ocean. They have survived several major destructions of the Earth and have witnessed the changes of the Earth several times. The mouth is at the front, mostly on the ventral side. The anus is at the back, mostly on the dorsal side.

There are usually tube feet on the back and tube feet on the ventral side. The internal skeleton is degenerate into tiny bone pieces. Many species have 5 rows of tube feet from mouth to anus. The anus is used for both breathing and excretion of waste. There are 10 or more retractable tentacles around the mouth, which are used for hunting or burrowing. Many species can release internal organs from the anus and then regenerate new ones, probably to escape from enemies.

The cloaca often contains symbiotic fish of the genus Carapus, many of which can release toxins that are lethal to small animals but are not life-threatening to humans.

Reference source: Baidu Encyclopedia - Sea Cucumber

Sea cucumbers live deep in the sea and cannot swim. They crawl on the seabed using their tube feet and muscles, and their speed is quite slow, crawling about three meters in an hour. They are born without eyes, and have no weapons or skills to kill enemies. So how did the sea cucumber family survive in the ocean world where the strong prey on the weak?

Super strong reproductive ability

In order to ensure that the species does not become extinct, sea cucumbers have acquired super strong reproductive ability in the long-term natural selection evolution process. An adult sea cucumber over 4 years old can lay about 5 million eggs at a time during the spring breeding season. In this way, even if there is a survival rate of one in ten thousand, the continuation of the species can be guaranteed.

Summer dormancy

We know that some animals on land (such as snakes) often have the habit of hibernation, but sea cucumbers choose to hibernate in the summer when food is abundant. When the water temperature reaches 20℃, sea cucumbers will move to the crevices of deep-sea reefs or hide at the bottom of rocks, not eating or moving, and their entire bodies will shrink and harden like a ball of thorns. Most animals will not eat them. They sleep for a whole summer and wake up in autumn to resume activities.

Predicting the weather

When the wind blows and the waves surge, the sea cucumbers that are not firmly attached will be swept into danger. However, sea cucumbers can predict the weather and hide in the cracks of rocks before a storm. Fishermen use this phenomenon to predict weather conditions at sea.

Color change

Sea cucumbers can change their body color depending on the environment they live in. Sea cucumbers living near reefs are brown or black; those living on the sandy seabed are yellow with spots; and those living in seaweed are green. This color change of sea cucumbers can effectively avoid harm from natural enemies.

Escape from the internal organs

When a vicious predator attacks, the alert sea cucumber will quickly eject all its internal organs from the excretion hole, floating in the water to attract the predator and let it be eaten. It can quickly escape with the help of the recoil force of the internal organs, which is called the "excretion function". Of course, the sea cucumber will not die without internal organs, and will grow a new set of internal organs after about 30 to 50 days.

Clone

The sea cucumber is cut into several segments horizontally and thrown into the sea. After 3-5 months, each segment will become a complete sea cucumber. This regeneration and repair function of sea cucumbers has always been a topic of in-depth research in medicine and bioengineering.

Rejection function

Someone has done an experiment: use a needle and thread or thin wire to penetrate the sea cucumber's flesh and tie a knot. Within half a month, the sea cucumber will magically expel the foreign body without leaving any trace in the sea cucumber's flesh.

The Mystery of the Iron Ball

A few years ago, people discovered that sea cucumbers store small pure iron balls under their skin. The diameter of the small iron balls is only 0.002 mm. So far, it is still unknown how these small iron balls are formed and what effect they have on sea cucumbers. It is speculated that these small iron balls may be used as a reserve when food is scarce, so that the pure iron balls in the body can be combined with anemic food. The mystery of the growth of sea cucumbers is directly related to the magical effects of sea cucumbers.