These are animals whose bodies are divided into a number of similar rings.

The head tapers to a point.

The tail is broad and flat.

Pores on the skin cover its body with slime. This slime keeps the worm clean, makes it slippery and kills germs.

The pointed nose drills into the soil and the flat tail presses it tight.

The slime is then used to cement the burrows.

Echinoderm is a common name for about 6 000 living species that live at all depths in all of the oceans of the world . These include:

Starfish, sea-cucumbers and sea-urchins.

Starfish have a mouth surrounded by 5 arms. At the ends of the arms are fleshy tube feet which the starfish uses to cling to things and to crawl about.

Sea-urchins have spines that are very well developed.

Echinoderms have simple nervous and circulatory systems.

This is the common name for 9 000 species of invertebrate animals found in all oceans of the world.

These include:

Coral, jellyfish and sea-anenome.

Some are cylindrical with the mouth and tentacles at one end.

Jellyfish look like an opened umbrella with tentacles hanging.

All coelenterates capture their prey in the tentacles and then kill them with poison from the stinging organ.