Common starfish: How they hunt and how long they live for

A beach in January might seem a bleak place but there is plenty see when the tide goes out. With this week’s full moon, we have extreme high and low tides and that means it will be a good chance to explore the nature living on Chit Rocks.

Just after lunch on Saturday and Sunday this weekend, the tide will be going down to its lowest point in the monthly cycle which exposes large areas of the rock shelf that has been cut as the Jacob’s Ladder cliffs have eroded in past centuries.

One species that you are likely to find at present is the common starfish. You might need to do some poking around because they hide when the tide is out. They have eye spots at the tip of each arm. They cannot actually see but they can detect light and dark. They use these to find places to hide, under rocks or in the seaweed.

These crusty orange creatures do not do anything quickly, if you are just walking past they seem motionless but, if you take your time, you will see that they creep very slowly, the arms can flex but they are not used to moved around. The starfish holds its shape and appears to glide across the bottom of the rock pool

Under each arm they have thousands of tiny suckered tube feet that stretch out , anchor and then pull the starfish along. If you pick up a starfish and turn it over you will see the tube feet waving about searching for a surface to grip. Please remember it is a living creature and return it safely to a pool.

Starfish are scavengers feeding on dead things they come across but they are also effective hunters. They have an excellent sense of what might be called smell or taste, they detect chemical signals in the water. They can’t chase prey but they will creep over things such as mussels and barnacles which cannot run away.

It is rather gross, but they feed but pushing their stomach out of their mouth onto the prey. The stomach releases gastric juices to soften the flesh, then it drags the food back inside the starfish body to finish digesting it. The stomach is strong enough to force open a mussel shell to get inside.

Like many sea invertebrates, starfish breed when the females release eggs into clouds of sperm released by the males. The microscopic babies float about as part of the plankton for several months before settling down on the sea floor where they have a life span of seven or eight years, if they are not washed up onto the beach by a storm.