JellyFish Facts

Jellyfish Body

Jellyfish Body picture

Jellyfish Body

Jellyfish invokes mixed reaction from beach goers. Its unusual appearance is amusing and fascinating to look at. However, the trouble it causes to those who encounter it is immense. It varies from mild to fatal stings. No wonder jellyfish bring forth extreme fear and intimidation in the minds of swimmers.

Jellyfish belong to the family of phylum cnidaria, which includes Hydras, polyps, jellyfishes, sea anemones and corals. While some like corals, are fixed and grow attached to rocks, jellyfish is mobile.

Skeletal system and brain is absent in jellyfish. Instead, it has a network of nerves called nerve net, which is capable of sensing odor, light and other similar stimulations. This simple yet effective nervous system helps the jellyfish to respond with lightning speed.

Jellyfish has two layers of skin - epidermis or the outer layer and gastrodermis or the gut lining. A layer of thick gelatinous substance called mesoglea fills the portion between these two skin layers. This gives jellyfish its name and the translucent appearance.

The main body of a jellyfish is bell-shaped with tentacles extending from underneath the body. Different species vary vastly in size, color and shape. The smallest measures barely an inch in diameter, while the largest jellyfish can measure up to seven feet across the bell. The tentacles also are proportional with some extending more than 100 feet.

The body of the jellyfish consists of more than 95% of water and less than 5% of organic matter. Due to this, jellyfish are extremely delicate and fragile. When removed from water, they collapse completely.

The tentacles are equipped with stinging capsules called cnidocytes like in all cnidarians. These have nematocysts, which has stinging mechanism with venom inside. When the tentacles come in touch with a likely prey, the stinging mechanism is activated. They shoot nematocyst filaments into the body of the prey like harpoons. Once these filaments stick to the prey, they release venom, which paralyzes them. By holding onto the prey with the tentacles, the prey is brought into the mouth of the jellyfish.

The mouth of the jellyfish is located at its underside. A gastro vascular cavity adjoining the oral opening serves as the stomach. The food entering the mouth is immediately digested in this chamber and the nutrients absorbed into the body. The nutrients reach all parts of the body through radial canals. The waste matter generated during digestion is expelled through the same opening.

As jellyfish doesn't have teeth or any other mechanism for chewing the prey, the food is swallowed and digested without breaking it down. The gastrodermis helps in digesting the food.

Jellyfish do not possess a heart, brain, respiratory system, skeletal system, central nervous system or blood. They breathe through their thin skin. The muscles present in the bell-shaped body help it in vertical movement. Jellyfish rely on ocean currents and tides for horizontal motion.

Jellyfish has the ability to live in extreme temperatures and a wide range of salinity. This makes it a common marine creature in oceans all over the world.

Learn more about Jellyfish, different Jellyfish Species, general Jellyfish Information, Jellyfish Pets and Jellyfish Safety




Written by and Sudarsana Sinha.

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