Jellyfish aren’t actually a “fish” – they are Cnidarians, which is a phylum of stinging aquatic creatures. Jellyfish are fascinating animals – from a distance! You wouldn’t want to get too close to one; their stings can be deadly!
Can you believe that these simple aquatic animals live without eyes, ears, or a brain? They use their nervous systems to detect the touch of other animals. A jellyfish has a “bell”, which produces jelly and encloses its stomach pouch. The mouth of a jellyfish lies on the underside of the bell. Oral arms dangle around the mouth, and tentacles hang around the rim of the bell. The arms and tentacles are covered in cells that can sting or kill its prey.
Jellyfish are drifters: they rely on the ocean’s current to get from one place to another. Some jellies can propel themselves through the water by pulsating their bells. Jellies eat the zooplankton and small fish that gets in its path.
The smallest known jellyfish is the Irukandji, which is extremely poisonous. This small jellyfish only measures 1-½ inches across. The Irukandji can be very deadly because it is almost invisible – swimmers don’t realize they’ve been stung until it’s too late.
The largest jellyfish is the Lion’s Mane jellyfish. These giants of the sea are found in the northern Arctic waters, northern Pacific, and northern Atlantic oceans. In 1870, the largest recorded Lion’s Mane jellyfish washed up on the shore of Massachusetts Bay; the bell of this jelly measured eight-feet across, and the tentacles were 120 feet long!
