JELLYFISH

There is a diversity of invertebrates in marine life. For instance, the Pelagia Notiluca jellyfish does not have a spine and is also considered a cnidarian (any invertebrate animal distinguished by the particular stinging structures in the tentacles surrounding the mouth). These mushroom shaped bells have eight hair-like marginal pink tentacles that measure up to ten meters in lenth. The average size of the Noctiluca is 6.5 cm diameter across the bell but they may grow to be 10 cm or more. The tentacles, oral arms, exumbrella (the top of the jellyfish), and gastric pouches are covered in cnidocytes, cells that eject a toxin-filled stinging thread. Noctilucas have 16 stomach pouches and 16 lappets, which are overlaps of the exumbrella. The exumbrella is covered with wart-like clusters of stinging nematocysts which is a specialized cell in the tentacles of a jellyfish that has a venomous coiled thread that can be let out in self-defense or to capture a prey. The uxmbrella edge is divided into eight lobes, where sense organs such as light receptors and odor pits are located. The uxmbrella can be bell-shaped or hemispherical, and color can range from purple to brownish-red. Pelagia also have eight marginal sense organs and sixteen marginal lobes. The medusa is filled with an abiotic gel-like substance called the mesoglea. Noctiluca is well-known for its beautiful luminescence. This jellyfish phosphoresces when it is disturbed and can leave a luminous mucous behind if touched which is called the "mauve jelly" by the British. If disturbed, it will bioluminescent, and this luminescence is often seen at night. It is not certain what causes luminescence in the Noctiluca, but it is not caused by cytolosis (disruption of cells) or muscular contraction. The bioluminescence is likely controlled by the nervous system; however no recent work has been done on this particular species to confirm this hypothesis. Jellyfish do not have complex eyes, but they do have light receptors