It is an important plankton in aquatic environment, belonging to Echinotheca. Jellyfish is a very beautiful aquatic animal. Its shape is like a transparent umbrella, and the diameter of the umbrella is large or small. The diameter of the umbrella of the big jellyfish can reach 2 meters. There are some whisker-like tentacles on the edge of the umbrella, and some tentacles can be as long as 20-30 meters.

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Predation:

They are carnivores, feeding on plankton, small crustaceans, polychaetes and even small fish. Due to the mechanical and chemical stimulation of food, hydra elongate their tentacles, release stinging silk sacs to entangle, paralyze and poison their prey, and then send food into their mouths.

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Although jellyfish are beautiful and docile, they are actually fierce. Because jellyfish have no respiratory organs and circulatory system, only primitive digestive organs, so the captured food is immediately digested and absorbed in the lumen. Once a jellyfish meets its prey, it will never let it go easily. But like rhinoceroses and birds that clean up parasites, jellyfish have their own companions.

sports

Jellyfish changes the volume of the inner cavity by shrinking the shell and squeezing the inner cavity, and ejects the water in the cavity to move by spraying water. Muscle fibers extending from the top of jellyfish epidermis to the end of umbrella body control the contraction and expansion of inner cavity.

The lumen expands, and water is slowly sucked in to fill the lumen; The inner cavity shrinks rapidly, squeezing water out of the cavity, and the thrust generated by the water jet makes the jellyfish move axially along the body.

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