Found throughout the world’s oceans in a variety of shapes, sizes and colours, there are over 2,000 species of starfish that call water their home. One of the most vibrant, fascinating creatures of its kind, there’s a lot more to starfish than just their unique look. There are all sorts of incredible facts and information about the starfish you might not know.
Here, we’ll take a closer look at the starfish in more detail! Or discover some of the other wonderful animals we have at Tynemouth Aquarium here.
Is a Starfish a Fish?
Despite their name, starfish aren’t actually fish! For a start, they don’t have gills, scales or fins as fish do, and they don’t have a backbone, which means they belong to a group of species called invertebrates, along with urchins and sponges.
And, because they’re not classified as fish, scientists prefer to call them ‘sea stars’.
Starfish are easily identified by a central disc, usually five arms, radial symmetry, and a tough calcium carbonate skin.
11 Impressive Facts about Starfish
Despite looking like quite simple creatures, starfish are amazing animals with a rich history on Earth stretching back millions of years. Let’s explore more fascinating facts about starfish.
Starfish have been on Earth for over 450 million years
The history of starfish goes back over 450 million years, to the Late Ordovician period. It was a time known for high sea levels along with a rapidly cooling climate that eventually led to an ice age.
There are over 1,500 species of starfish
Starfish might share a similar shape, but out of the 1,500 species of starfish, very few of them look much alike. For example, not all starfish are even shaped like stars, they also range in colours and sizes, from the 1cm Parvulastra parvivipara to the 1m Sunflower sea star (Pycnopodia helianthoides).
Starfish don’t have brains or blood
It seems strange to think that starfish can even survive without a brain or any blood, but if nothing else, starfish are a species with their own way of doing things. Instead of blood, seawater is pumped through their body as a replacement, with the water providing key nutrients to the starfish, which allow its organs to function properly.
They have the ability to regenerate limbs
Amazingly, the starfish has the ability to regenerate its own arms! If they’re attacked by a predator, they may end up losing limbs, but the starfish can also amputate one of its arms in order to hide and escape, throwing other animals off their trail.
Even more incredibly, if the severed appendage is not harmed, then it can heal itself and regenerate because most of its vital organs are kept in the arms. When fully regenerated, this creates a genetically identical starfish!
Starfish have eyes on each arm
A creature as fascinating as a starfish couldn’t possibly have eyes in as boring a place as a head; they’re on their arms.
Although their eyes can’t see things in the same ways that ours can, the eyes, which look like small red dots, are able to detect different shades of light, allowing them to navigate through the ocean. This lets them hunt for food and avoid becoming a meal themselves.
They use tiny tube-like feet to move around
At the end of each of its arms, the starfish has hundreds of little feet. In order to move, they fill these feet with water, which causes the arm to move as a foot would. And they can move a lot quicker than you might expect!
They have a unique digestion process
Starfish love to eat things like mussels, clams, snails and barnacles, which all have armour-like shells to protect themselves. The starfish uses its arms to wrap around the animal’s shell, then pushes its stomach out of its mouth and into the open shell. The animal is then digested, and the starfish’s stomach slides back into its body.
This means if it’s especially hungry, it can eat prey that is much larger than it can fit into its very small mouth.
Starfish are exclusively saltwater creatures
If you’re at the beach, you’re quite likely to come across a starfish because of the abundance of saltwater. Starfish are exclusively saltwater animals, using the nutrients found in saltwater as a replacement for their blood. Fresh water simply could not sustain them.
Starfish live all over the world
No matter where you are in the world, you’re always quite close to starfish, as long as you’re near the sea. They’re found in oceans all over the world, in rock pools, kelp forests and even on the ocean floor!
They are not social creatures
Starfish aren’t very social creatures, preferring to spend most of their time on their own. However, they do sometimes join up during certain times of the year to feed or to reproduce.
Starfish are carnivores
Starfish aren’t the most terrifying of creatures, but they’re still a serious threat to animals like clams, coral, and mussels. Despite looking quite cute, they’re exclusively carnivores, making use of their unique adaptations to get through the tough exoskeletons of their prey.
Learn More about Starfish at Tynemouth Aquarium
At Tynemouth Aquarium, we’re lucky enough to house several species of Starfish in our exhibits. We have many starfish within our tanks, including the crimson knobbed starfish (Protoreaster linckii), purple sunstar (Solaster endeca), and common starfish (Asterias rubens).
Our team of experts are always available to teach you even more about the starfish we have, or you can join one of our scheduled talks to learn about the creatures at Tynemouth Aquarium.
It’s clear to see that starfish are definitely a more interesting creature than they get credit for. Their miraculous adaptations make them a marvel of the ocean and creatures of great importance to the wider ecosystem. To see them up close at Tynemouth Aquarium, book your tickets now!
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