Sea star facts!
Find out all about these incredible invertebrates!
Grab your snorkels, gang, and join us as we discover one of the ocean’s most peculiar creatures! Ready? Then check out our fascinating sea star facts…
Phylum: Echinodermata
Family: Asteriidae
Classification: Invertebrate
IUCN status: Not Evaluated
Lifespan (in wild): 35 years
Weight: Up to 5kg
Body size: 1-65cm, depending on species
Diet: Carnivore
Habitat: Ocean
Range:
First things first – despite their common (and very misleading!) name, sea stars (or starfish) are neither stars, nor fish! Since they don’t have a backbone, they belong to a group of species called invertebrates, which also includes urchins and sponges.
There are around 1,600 different species of sea stars living in the world’s oceans, where they occupy every type of habitat including tidal pools, rocky shores, sea grass, kelp beds and coral reefs. Some sea stars are even found on sandy seabeds 9,000 metres deep!
Most sea stars sport spiny skin and five arms surrounding a central disc-shape body – although some can grow as many as 50 arms. Their arms are covered with pincer-like organs and suckers that allow the animal to slowly creep along the ocean floor. They also have eyespots on the tips of the arms, which allow the sea star to sense light and dark, and help it find food.
Favourites on the sea star’s menu include molluscs like clams, oysters and snails. And it has a pretty impressive way of eating! After attaching its body to the chosen prey, the sea star extends its stomach out through its mouth.
Substances (called enzymes) from the stomach then begin to digest the food. This allows the nutritious grub to pass inside the stomach, which in turn retracts back into the body where digestion is complete. Cool, eh? Tiny organisms that fall victim to the super sea star can be swallowed whole.
Sea star predators include certain fish species, sharks, manta rays and even other sea stars! To help protect themselves, these incredible invertebrates have evolved several effective defence mechanisms. As well as their tough, prickly, armour-like skin, some have striking colours that camouflage them amongst plants and coral, or scare off potential attackers.
And check this out, too – these cool creatures are able to regrow lost or damaged limbs! If under attack, some sea stars will even shed an arm to escape the predator. Cunning stuff!
Sea stars aren’t social creatures – instead they are solitary and spend most of their life alone. They will, however, sometimes congregate in large groups during certain times of the year to feed.
What’s your favourite sea star fact? Tell us in the comments below!
Picture credits – Blue sea star: Song Heming, Dreamstime. Red sea star: Mrtolc, Dreamstime. Yellow sea star: Natalie11345, Dreamstime.
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COMMENTS1
Rutwa cha
Nice
Isaac
Cool! I love starfish!
Enya
This helps me learn more and i also share some of this to my classmates
Loulou
Great
Cool
lion
I use this for my writing
lion
Sofia
Cool
Sofia
Jayden
Nice
Luis
Faisa
Amizing Wow
yusriyah
cool
Tyler
Noa
You describe the words Great
Kimberly
Do starfish get along with other sea creatures?
star fish have butts
Hi
Nice
Nice
Home learning, Thursday 21st May – Ellel St John's CE Primary School
[…] https://www.natgeokids.com/uk/discover/animals/sea-life/starfish-facts/ […]
Olivia
cool
Issy
AWESOME!
smithd1
AMAZING!!!
Ivy
Soooo cool!
Zara
Cool
ramona
starfish are amazing. I like how they have no back bone.
Ngarewa
Very interesting. I love star fish
Charlize
I love starfish!
gordon
cool!!!!!!!!!!!!!!
A.y17
I have sen a blue star fish
bdbhds
wow i didnt know any of that ;)
BOB
AMAZING!!!
lucy
wow amazing
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