Starfish

There are about 2,000 species of sea stars or starfish as they are more commonly known.

Star fish have are able to regenerate lost body parts

When injured by a predator the starfish can regrow any lost arms. As most of its vital organs are housed in its arms, a new starfish can regenerate even from a single arm and a portion of the central disc.

Starfish have Armour for protection

Depending on the species, a sea star's skin may feel leathery or slightly prickly. Sea stars have a tough covering on their upper side, which is made up of plates of calcium carbonate with tiny spines on their surface. This armour is used for protection from predators.

Starfish have no blood

Instead of blood, sea stars have a circulatory system made up primarily of seawater. Seawater is pumped into the animal's water vascular system through its sieve plate. This is a sort of trap door called a madreporite, often visible as a light-coloured spot on the top of the starfish. From the madreporite, seawater moves into the sea star's tube feet, causing the arm to extend. Muscles within the tube feet are used to retract the limb.

Starfish have eyes

Starfish also have an eye at the tip of each arm. This means that a armed starfish has 5 eyes but the sunstar has 40 eyes as it has 40 arms.

Each sea star eye is very simple and looks like a red spot. It doesn't see much detail but it can sense light and dark, which is just enough for the environments the animals live in.