ANTICS Starfish

Looking very stylish in his beach shorts and sun hat, our vet Joe Inglis is off to the seaside to see what he can learn about these weird and wonderfully pointy animals.

Starfish are marine invertebrates (which means they don’t have bones supporting their bodies). They live on the seabed of every ocean around the world, from the frozen depths of the Arctic and Antarctica to the warm waters of the tropics. They have super-tough skin with scales or spines to protect them from predators.

Super symmetry

With five or more arms radiating out from a central disc, starfish look very different from most animals as they can’t be divided neatly into left and right sides. Instead, starfish show what’s called radial symmetry , which means they look the same on either side of lots of different lines drawn through their central discs.

The number of arms that a species of starfish found in the Antarctic can have. That’s a lot of gloves to find when it gets really cold!

Water-powered

Unlike vertebrate animals that use muscles and bones to move their bodies around, starfish use water power! They squeeze sacs called ampullae which push seawater through canals in their arms and into their sticky tube feet underneath. This hydraulic power allows them to move their arms and grab things with their feet – but it’s not very fast. Most starfish can only move around 15 cm per minute, which means a 100-metre sprint would take them over 11 hours!

Prickly predators

Starfish are mainly carnivorous, eating small invertebrates like sea snails, shellfish such as clams, and small fish, although some also enjoy a nibble of seaweed or plankton. One species, called the eats coral polyps

They cause serious damage to reefs such as the

Starfish have no brains

Answer on page 34

What’s bigger than a starfish? A galaxy fish!

Disgusting diners

To catch and eat their food, many species of starfish do something really gross – they force their stomachs out through their mouths and wrap them around their prey! They then partly digest them before sucking them back inside with their stomachs.

One of the most amazing abilities starfish have is that they can completely regenerate or pulled off by a predator. The process can take months or even years to complete. Even more incredibly, a detached arm can actually regrow the rest of a starfish body, creating a new clone ee-ha, I’m riding the waves!

This detached arm is growing a new body!

How many triangles are there in the picture?

Check your answer on page 34.

Match the marine creatures to the clues in this seashore quiz!

Watch out, this animal might steal your chips! Scientists in Cornwall have found that they actually prefer food that has been handled by humans. They also eat fish, young birds, eggs, small mammals, insects, fruit and dead animals.

You might think this fish would gallop around but it prefers to cling to seaweed and seagrass with its long tail. It doesn’t have teeth so it sucks up its prey of shrimp and plankton.