Facts about Starfish


Our departing Divemaster, Jordan ‘Dingus’ Walden, regular contributor to our Crystal Blog, composes one last literary masterpiece on….

Wait for it….

A True ‘Sea Weirdo’

What are starfish? They’re not really fish as we normally think of fish, and they’re certainly not stars! These very mysterious ocean-beings are not actually related to fish at all. Starfish belong to a group of marine invertebrates which includes sea cucumbers, sea urchins, and a bunch of other sea weirdos.

Some “Starphisch Faks”

They Look Like A Star

Their starry shape is the reason they’re named starfish, rather than say ‘pointy triangle sponge’. Most species of starfish have five arms, but there are sea stars with ten, twenty, or even forty arms. The one with forty arms is called the ‘sun star’ probably because it’s so damn big.


They may have different numbers of arms, and some may be real big and others real little but one feature that all starfish share is their radially symmetrical bodies, meaning all starfish can be divided into five equal pieces.

Though we’re not advising you to go cutting up starfish..!!

The Regeneration Game

But if you did go cutting up a starfish – fun fact; they can actually regenerate their missing body parts. If a predator eats part of the starfish, the remaining part will develop missing arms and bring back its previous look after some time. This ‘regeneration’ process can last up to a year though.

Meat Lovers (with huge stomachs)

Starfish are carnivores; they feed on clams, shells, and mussels. They have two stomachs, one of which can be pushed outside of the body during eating. This allows them to eat larger prey, which can’t fit in the sea star’s small mouth.

Upside Down, Back to Front!

A starfish’s mouth is located on the underside of its body, and its anus is located on the upper side of its body… pretty much the opposite of humans. Starfish move using tube feet, which consist of hundreds of projections on the underside of their bodies. These tube feet projection things are used for walking and catching food to eat.

Absolutely Brainless

Starfish may have feet, mouths and anuses; but they still lack a brain. They don’t have brains, and they don’t even have blood! Instead of blood, sea water circulates through their body.

Body Armour

The surface of a starfish body is covered with bony skeleton which often contains different kinds of spikes and thorns. This protects them from predators like sea otters, rays, sharks, seagulls, and fishes and stuff.

Sexually Confusing

Starfish have sex by combining reproductive cells of males and females, but they can also reproduce asexually (boring!) by dividing its body at the centre and regenerating the missing part. When starfish reproduce sexually, males and females release millions of sperm and eggs in the water, where they mix together to form a fertilized egg to make a new starfish.

They produce so many sperms and eggs, because few of the eggs survive – probably because the dudes don’t know how to do it right! Starfish are not hermaphrodites (animals which have both types of sex parts), but they are capable of changing the gender whenever they like during their lifetime.

This would probably be very sexually confusing for them – if they had brains!

Super Weird – But Pretty Interesting

In conclusion, starfish are super weird but pretty interesting. So the next time you’re diving in Koh Tao or anywhere else in the world for that matter, when you swim by a starfish stop a minute and think, “maybe you and I aren’t so different, you little pointy triangular sponge. We both have anuses, mouths and feet – and not much of a brain.”

Continue swimming on by full in the knowledge that you now have a greater appreciation for these star-shaped little weirdos!

Author: Jordan ‘Dingus’ Walden (PADI DM #377541)

Crystal Dive Koh Tao

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