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7 Amazing Starfish Facts

  • Wednesday 23rd May 2018


There are over 2000 different species of starfish, these unique marine animals have various different colours, shapes, and sizes. Starfish, also known as Sea Stars, are one of the most beautiful looking animals in the vast ocean. They have a surprisingly unusual anatomy, with no brain or blood, yet are able to digest food outside their body.

Starfish can regenerate their own arms       

Regenerating their own arms is perhaps one of the most useful things a starfish can do. This attribute can be used in many different ways. Arms can be lost when a starfish comes in contact with a predator, or it may be amputated in order to hide or escape from one.

Arms can take months, even years to fully regenerate, so it has to be a pretty serious situation to lose one. Incredibly, if the severed leg is not harmed, it can heal itself and even regenerate - resulting in a genetically identical starfish. Pretty cool, right?

They have no brain or blood!

With no brain or blood it seems crazy to think starfish can survive in the depth of the vast ocean. However, they find very clever and simple ways to get around it.

Seawater is pumped throughout their body as a replacement for blood, with the water delivering key nutrients to the starfish allowing its organs to function properly. The use of water saves space as there is no need for a complex blood system, also since seawater is highly abundant they will never run out of it.

Starfish may have no brain, but they are certainly not fools!

They wear tough, leathery skin

Starfish are layered with an upper skin made out of calcium carbonate. This strong material makes the skin tough and difficult for hunters to breakdown.

Some species of starfish will even go a step further with the addition of numerous spines on their skin, acting as a layer of armour to deter predators.  

Starfish have eyes

Lacking a brain, blood and even a central nervous system, it might come as a surprise to you that starfish have eyes.

Just to further add to their unusual anatomy, their eyes are on the end of their arms. Whilst their eyes may not be able to see in fine detail like our eyes can, they are able to detect different shades of light allowing them to navigate their surroundings - allowing them to hunt for food and hide from predators.       

Starfish move with hundreds of feet

Starfish are equipped with hundreds of tiny little feet at the end of each arm.

To move, they fill these feet with seawater, causing the arm to move like a foot would. This mechanism allows the starfish to move - much quicker than you might expect. Visit our rock pool to see this first hand!

Starfish can eat outside their body

Due to their tiny mouth on the underside of their body, starfish have adapted an ingenious way of eating things larger than it can fit in their mouth.

They have a stomach that can digest food outside their body, so that it can fit in their mouth. This allows the food to be further broken down inside the body.  

Not all starfish are star shaped

Almost all starfish are shaped like a star, which is how they get their grouped name. However, there are a few special cases.

The Cushion Starfish has a round blob-like shape, while having all the genetic qualities needed to be a starfish. This starfish is actually much gentler than other starfish, feeding on detritus and plants. Other starfish will tend to feed on clams or oysters.