Invertebrates

Molluscs are an extremely diverse group of creatures that includes the octopus, squid, snails and clams. Molluscs don't have skeletons. Only some molluscs have shells.

A sponge is an animal that lives in the sea whose body is made up of lots of holes. Most sea sponges have hard skeletons, and the holes are for filtering food out of the water and so they can breathe. Some species of sponge have soft skeletons and people used to catch them to use them for cleaning and packaging, but there are now almost none left. Today, sponges found around the house are made by people, and are not animals caught in the sea.

The starfish, or sea star, is not a fish - starfish have no skeleton. They are related to sea urchins. As they have no skeleton and hence no legs, they don't move around by walking. They move by pumping water around through tubes on the base of their arms. Not all starfish have five arms, some have more. Starfish eat sea creatures with shells that move slower than it does. Starfish have two stomachs, and one of them can be put outside the starfish's body. So they eat clams and other shellfish by forcing them open and putting their stomach inside the clam's shell. Some starfish can regrow arms if they are cut off. Some starfish can grow from the cut-off arm as long as some of the central portion of the starfish is still attached. Starfish send their eggs out to drift into the open sea where they hatch into small swimming larva. When the larva are old enough, they sink to the bottom of the sea and turn into adult starfish.

Earthworms live under the ground in your garden. They eat fallen leaves and make the soil better for plants to grow in. Worms are slimy, to help them travel through the soil.