Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles. Jellyfish and sea jellies are the informal common names given to the medusa-phase.
Special about jellyfish
Jellyfish have tiny stinging cells in their tentacles of stun or paralyze their prey before they eat them. Inside their bell shaped body is an opening that is its mouth. Tentacles hang down from the smooth baglike body and sting their prey. Jellyfish stings can be painful to humans and sometimes very dangerous.
Where do jellyfish live
They are found in oceans all over the world : at the surface, deep beneath the sea, in warm water, in cold water, some species of hydrozoa , even live in fresh water.
Jellyfish made of
Lacking brains, blood or even hearts, jellyfish are pretty simple critters. They are composed of three layers; an outer layer, called the epidermis, a middle layer made of a thick, elastic, jellyfish-like substance called mesoglea, and an inner layer called the gastrodermis.
Jellyfish reproduce both sexually and asexually.one generation (the medusa) reproduces sexually and the next generation (the polyp) reproduce asexually….For both species, fertilized eggs developed into a multi-cellular plan planula and then into polyps that live on the sea floor .
Researchers describe jellyfish as a ‘Gingerbread house ‘ for fish,providing both food and shelter. Scientists at Queen’s University ,belfast,have discovered that jellyfish are providing habitat and space for developing larval and juvenile fish.
Some jellyfish are clear, but others are in vibrant colors such as pink,yellow, blue, and purple and often are luminescent.