Jellyfish system. Nematocysts, which deliver the sting, are located mostly on the tentacles; true jellyfish also have them around the mouth and stomach. Jellyfish do not need a respiratory system because sufficient oxygen diffuses through the epidermis. They have limited control over their movement, but can navigate with the pulsations of the bell-like body; some species are active swimmers most of the time, while others largely drift. The rhopalia contain rudimentary sense organs which are able to detect light, water-borne vibrations, odour and orientation. A loose network of nerves called a "nerve net" is located in the epidermis. Although traditionally thought
Lion's mane jellyfish lion's mane jellyfish. This was later corrected – in 1864, a bootlace worm ("Lineus longissimus") was found washed up on a Scottish shore that was long. ("That" claim has its critics: because bootlace worms can easily stretch to several times their natural length, it is possible the worm did not actually grow to be that length.) Lion's mane jellyfish The lion's mane jellyfish, also known as the giant jellyfish or the hair jelly, is the largest known species of jellyfish. Its range is confined to cold, boreal waters of the Arctic, northern Atlantic, and northern Pacific Oceans. It is common