Cnidaria

ocean · stinging cells · invertebrates · ancient animals

Jellyfish and corals. Cnidarians include jellyfish, sea anemones, corals, and even tiny hydroids. Over 11,000 species live in oceans and freshwater around the world.

Stinging superpowers. Cnidarians have special cells called cnidocytes that work like tiny harpoons filled with venom. They shoot these weapons to stun prey and keep predators away.

No central brain. Instead of a brain, cnidarians have a nervous system spread throughout their whole body like a net. This lets them sense what is happening all around them.

Jelly-like bodies. A cnidarian's body is mostly made of a gooey substance called mesoglea squeezed between two thin layers of skin. It is mostly water, which is why jellyfish feel so squishy.

Two ways to make babies. Many cnidarians can reproduce both sexually by making eggs and sperm, or asexually by just splitting into clones. This helps them survive in changing ocean conditions.