Did you guess correctly? Welcome to the wonderful world of sea stars!
Sea stars are a common sight in rock pools along the Mornington Peninsula and they have been present in the world’s oceans for more than 450 million years!
A close examination of sea stars shows many features that appear to be out of a science fiction novel! A sea star has bony hard body walls which incorporate colourful plates of all shapes and designs. Some are flat, and some include spines which are a great defence against predators.
Sea stars have terrible table manners and they eat their food outside their body! To eat, a sea star climbs onto the food, pushes its stomach out through its mouth (which is on the underside of the body), wraps it around the food and begins to digest it. When the sea star is finished, it withdraws the stomach back into the body. This way a sea star can eat food that would be too large to fit in its mouth.
They have feet but no legs and the feet come from their arms! On the underside of each arm is a groove which contains hundreds of tubular feet, each ending in a sucker. These flexible feet can be withdrawn into the groove or extended when seawater is pumped into them.
A sea star’s feet has noses! The tubular feet, especially those at the end of the arms can detect chemicals in the water, such as food. You may have seen the ends of the arms turned up with the tubular feet extended out in all directions, they are tasting the water! When an arm finds food, the suckers and feet work together to pass the food along the arm to the mouth.
Sea stars can regrow lost parts of their bodies. If a predator eats part of an arm, the sea star can regrow that eaten part! Some sea stars take this a step further and reproduce by dividing in half then growing the missing parts.
A sea star that can behave in these ways is even more special when you know that it has no brain to control any of this! The movement of a sea star is very graceful, they appear to glide over the surface. Have a look at the time-lapse below to see how smoothly sea stars move.
If you would like to know more about the amazing world that exists in the rock pools or would like to join us in person when the time is right for one of our amazing rockpool rambles please do not hesitate to contact our Education Director Mandy Robertson on (03) 5979 7100 or by email to email@example.com.