Jellyfish

Jellyfish Facts;
The Jellyfish is a unique kind of marine life. It stands out from other fish due to its shape and other attributes. Here are some facts about Jellyfish.

Jellyfish belong to the Scyphozoan class of invertebrates.Not all jellyfish can be termed as being 'fish'. Their class name comes from the Greek name 'skyphos', which means a drinking cup.

Jellyfish is present and found in every ocean in the world. The lifetime of a jellyfish is at the most three or six months.They have two body forms through their life cycle - the polyp stage and the medusa stage. In the polyp stage, they are in the form of a sessile stalk with their mouth and tentacle facing upwards. In this stage, they catch passing food. The second stage of the jellyfish' body structure is more popular. During this stage, they have an umbrella shaped body called the bell.

This body structure is known as the medusa and tentacles of the jellyfish hang from the border of the bell. The body of a jellyfish is made up of almost 90 to 94% water.

Jellyfish are made up of an epidermis, gastrodermis and mesoglea.Jellyfish do not have a central nervous system,a circulatory system, respiratory system, or a osmoregulatory system. They have an incomplete digestive system and therefore use the same orifice for intake of food and expulsion of waste materials.

The jellyfish doesn't have a brain or other sensory organs. The jellyfish have small sensory organs on their around its bell. These sensory organs are known as rhopalia. Therefore, the jellyfish uses its rhopalia and nervous system to identify light and odor. The jellyfish use their 'nerve net' to detect the touch of another organism. This type of simple nervous system is found at the epidermis of the jellyfish.

A group of jellyfish is called a 'smack'. Jellyfish feed on small protozoa, large metazoa and other small fish in the sea. They generally trap these in their tentacles. Some jellyfish do not have tentacles at all.

The male jellyfish releases its sperm into the water, which then travels to the mouth of the female jellyfish. This procedure allows for the fertilization of the ova. Most jellyfish lodge the eggs in their oral armpits, forming a brood chamber for fertilization.

The tentacles of a jellyfish are an important defense mechanism. Each tentacle is covered with stinging cells, known as cnidocytes. Jellyfish do not have any water motion, or are not hydrodynamic. This hampers their swimming speeds. It is necessary for them to create water currents which reaches their tentacles. Jellyfish make this possible by opening and closing their bell shaped bodies in a rhythm.

Jellyfish swim by contracting and expanding their bodies. They do not have scales or shells. If exposed to the hot sun, they disappear, leaving only a circle of film. Jellyfish have a defense mechanism of oral arms or tentacles which are covered with organelles called nematocysts. These nematocysts are paired with a capsule which contains a coiled filament that stings. The filament unwinds and launches into the target, thereby injecting toxins upon contact by foreign bodies.

Jellyfish are generally not dangerous to humankind. However, some jellyfish can be very toxic, and cause deaths in humans. Recently, two deaths attributed to jellyfish were reported in Australia. However, a jellyfish sting is extremely painful and can also cause various allergies in humans.

Jellyfish lead a more difficult life in captivity as compared to other marine life. They cannot accustom themselves to the bound atmospheres in the aquariums, secondly, since Jellyfish cannot swim as fast as the fish, they require the natural currents of the water to transport themselves.

(http://www.buzzle.com/articles/facts-about-jellyfish.html)

Today we learned about Jellyfish! The kids had a lot of fun making their very own Jellyfish. Check them out :) We used colored tissue paper and glue to create a glossy look.