Jellyfish

Moon Jellyfish (Aurelia aurita)
The moon-like shape and translucent white color gives these jellyfish their name. They are found in the Atlantic Ocean from the arctic to Mexico and in the Pacific Ocean from Alaska to Southern California. The Moon Jellyfish typically reach 6-8 inches in bell diameter, but are known to exceed 20 inches. Their tentacles are short and located on the edges of its bell (body). These tentacles are only slightly venomous. The easily visible four crescent shaped organs is the gonads of the jelly; it surrounds the central mouth. Immediately above the gonads is the stomach. After feeding the stomach contents of the moon jelly are clearly visible. In the wild, they often occur in huge masses called smacks. They feed on zooplankton, mollusk larvae, and crustaceans.

Jellyfish facts
· No Brain! “true” jellyfish have an elementary nervous system which consists of receptors. These receptors are capable of detecting light, odor, and other stimuli.
· Who eats who? Jellyfish are carnivorous, eating mostly zooplankton, comb jellyfish and occasionally other jellyfish. They better watch out because spadefish, sunfish, and leatherback turtles love to eat jellyfish.
· Ouch! Stinging structures (cnidocytes) may vary according to species . They generally consist of many tiny hollow coiled threads with barbs lining its surface. Stinging occurs when the barbs come into contact with another object. The severity of the sting depends on the species, penetrating power of the barbs, thickness of the victim’s exposed skin,and the sensitivity of the victim to the venom.

Typical life cycle of jellyfish
1 Adult female medusa eggs are fertilized by sperm from a male.
2 The fertilized egg develops into a larva and hairlike growths on its body help it swim to the bottom.
3 Here it attaches and begins to grow into a polyp.
4 As the polyp grows medusas begin to form, stacked upside down like saucers.
5 One by one, these “saucers” break off and swim away as young jellyfish.
6 Soon the young jellyfish will be fully developed medusas and begin the free-swimming life of an adult jellyfish.