Biology of Sea cucumber RN.pptx

Biology of sea cucumber
Marine Ecosystem, biodiversity and conservation

1. Sea cucumber RAGHUNATH MFSc-1 st yr FSM-2021-20-07

2. Introduction Sea cucumbers   are echinoderms  from the class   Holothuroidea . Their closest relatives are starfish and sea urchins species worldwide is about  1716  with the greatest number being in the Asia Pacific region . serve a useful role in the marine ecosystem as they help recycle nutrients, breaking down detritus  and other organic matter after which bacteria can continue the degradation process Smallest species can reach 0.12 inches, while largest species can reach 3.3 feet in length. Most species are usually 3.9 to 12 inches long.

3. Sea cucumbers use yet another interesting technique when they are faced with danger. They are able to expel internal organs along with toxic substance (called holothurin ) toward the predators. All missing organs will be regenerated in the next 1.5 to 5 weeks . Diet of sea cucumbers consists of decaying organic matter (from the sea floor) and plankton. Sea cucumbers are nocturnal creatures

4. Sea cucumbers can be often seen in large colonies. 1000 sea cucumbers per one square meter can be found along the coasts of New Zealand . Sea cucumber are able for self-reproduction Most species live between 5 and 10 years in the wild.

5. Sea cucumber biology Digestive system Many species possess an  oesophagus and  stomach, but in some the pharynx opens directly into the intestine . The intestine is typically long and coiled, and loops through the body

6. Nervous system Sea cucumbers have no true brain. A ring of neural tissue surrounds the oral cavity, and sends nerves to the tentacles and the pharynx.

7. Respiratory system Sea cucumbers extract oxygen from water in a pair of "respiratory trees" that branch off the cloaca  just inside the anus, so that they "breathe" by drawing water in through the anus and then expelling it. The respiratory trees also act as excretory organs.

8. Reproductive biology No distinct sexual dimorphism Breed twice in a year, spawning season – March to May October to December

9. Life cycle of sea cucumber

10. How they are protected ? Legal protection: at present, in India, protection is equivalent to tigers. Hunting restrictions: External breeding: People’s organization: Sea shepherd conservation society.

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