Starfish: 21 Facts You Won’t Believe!

Read these starfish facts about the beautiful sea animal with five or more arms.

Starfish or sea stars are seawater species of the Asteroidea class. The invertebrates star-shaped echinoderms are found in seawater or freshwater. Marine starfish sea creatures are also known as Asteroids. This is because they belong to the Asteroidea class.

Marine invertebrates have approximately 1500 species in all the oceans of the world. They are found in fresh water and seawater 19685 ft (6,000 m) below the intertidal zone. Sea stars normally have five arms. However, some have more arms than the usual starfish. They have a central disc with a smooth, granular, or spiny upper surface covered in overlapping plates. The starfish sea species are available in several colors. The species of sea stars can be found in blue, gray, brown, red, yellow, orange. They are in the radial symmetry stage after they grow from larvae.  Their mouth is located at the center of the lower surface in sea water with tube feet controlled by the hydraulic system. Their stomach is located outside their body along with a few vital organs. Moreover, sea star animals use sea water to pump nutrients from their nervous system.

Sea star species have suspension-feeding as their feeding behavior. Their life cycle is complex since they produce in both sexual and asexual ways. The asexual way to reproduce is by regeneration of damaged parts. Sea star species live for up to 35 years and tend to shed arms while defending themselves.

The vital ecological roles are known to be occupied by Asteroidea. The best examples of species in ecology are the ochre sea star and reef sea star. Sea stars are collected at times by people of some culture to be used as design, logo, and even for them to be eaten. However, starfishes have poison in them. Therefore, in order to eat them, it is important to remove their poison.

After this, you may also check our articles on mimic octopus facts and the anchovies facts.


Fact File

What do they prey on?

Snails, microalgae, bivalves, sponges, and other small sea creatures

What do they eat?


Average litter size?

2.5-65 million eggs

How much do they weigh?

10.8 lb (4.9 kg)

How long are they?

5-10 in (12.7-25.4 cm)

How tall are they?


What do they look like?


Skin Type

Spiny skin

What are their main threats?

Reduction of coral reef habitat, pollution, and marked changes in water temperature

What is their conservation status?

Nearly Threatened

Where you'll find them

Ocean, seas, and beaches


The Indian Ocean and the Pacific Ocean





Scientific Name






Starfish Interesting Facts

What type of animal is a starfish?

Starfish is a star-shaped animal found in depths of marine water bodies belonging to the Asteriidae family.

What class of animal does a starfish belong to?

Starfish or sea star are seawater species of the Asteroidea class.

How many starfish are there in the world?

There are 2,000 species of sea stars in the world.

Where does a starfish live?

Starfish can be found living in the ocean or the sea.

What is a starfish's habitat?

Seastar or starfish’s habitat is the oceans of the world. Their habitats are tidal pools, tropical coral reefs, rocky shores, seagrass meadows, deep-sea floors, and kelp forests. They’re mostly found in the depth of water bodies.

Who do starfish live with?

Starfishes are solitary creatures. They prefer to live alone instead of living in groups. However, after certain years of their life, they prefer to live in groups so that it can be easier for them to feed.

How long does a starfish live?

The lifespan of an average starfish according to starfish facts is said to be 34-35 years.

How do they reproduce?

Starfish’s reproduction and life cycle are unique. These sea creatures with five arms can reproduce sexually and asexually. Sexual reproduction occurs when a male and female starfish mate with each other. Asexual reproduction happens when the starfish splits its cells into two parts, also known as fission. They can also reproduce through autotomy. Moreover, with regeneration, they can regenerate lost limbs.

What is their conservation status?

The conservation status of starfish is Nearly Threatened.

Starfish Fun Facts

What do starfish look like?

Five-armed starfish have a beautiful appearance. They have spiny skin with approximately five arms and a central-shaped body. However, some starfish have more than five arms and can grow up to 50 arms. Their arms allow them to creep along the floor. This happens due to the pincer-like organs it is covered in. Their body has arms that come out from the central disk in the center of their body. Furthermore, starfishes are available in different shades of red, yellow, pink, green, and blue.

The sea invertebrate can prey upon species larger than its size.

How cute are they?

Starfish’s appearance can be considered extremely cute. Their star shape makes them even cuter and appealing. Moreover, they are collected by some people due to their cute appearance.

How do they communicate?

Starfish communicate differently. In recent research, scientists have found out that starfish communicate by releasing chemicals. They release chemicals in the water and send signals to each other.

How big is a starfish?

Starfish have a tiny bodies. They are 5-10 in (12.7-25.4 cm) long.

How fast can a starfish swim?

Sea stars don’t swim they move around on the seafloor. Some species of sea stars are fast predators that move rapidly.

How much does a starfish weigh?

The weight of an average starfish is said to be 10.8 lb (4.9 kg), however, a crown-of-thorns starfish weighs 0.4-6.6 lb (0.2-3 kg).

What are the male and female names of the species?

There are no specific male and female names of the species, they are simply referred to as starfish or sea stars.

What would you call a baby starfish?

A baby starfish is known as a baby sea star or baby starfish.

Is a starfish a crustacean?

No, starfish is not a crustacean. The sea stars are marine invertebrates.

How many tube feet does a starfish have?

An average starfish has a minimum of two rows of tube feet.

What is a starfish's main predator?

The main predators of starfish are sharks, sea turtles, and fish.

In what phylum are starfish found?

Starfish are of the Echinodermata phylum.

Is a starfish an amphibian?

Starfish is an invertebrate sea creature. They are not amphibians, rather they are echinoderms.

What do they eat?

Starfish can digest creatures larger than their mouth, so they prey on species larger than them. They hunt oceanic creatures like clams, oysters, arthropods, sand dollars, snails, and small fish. They are carnivorous creatures but they also feed on green algae and organic detritus.

Are they dangerous?

Several people believe that starfish are dangerous for them. Starfish have spikes that may make them seem harmful. However, starfish are not dangerous or poisonous nor can they kill humans. Not all species have venom in them but some species like sea urchins can be harmful. Sea urchins have venomous substances in them. Hence, it is better to not poke or step on any sea urchins if seen anywhere.

Would they make a good pet?

Starfish can make a great pet. This is because they can look adorable in your aquarium. However, saltwater invertebrates require a lot of attention and care. These marine species need special care with a diet that includes their choice of digestible food. With their ability to regenerate lost arms, they can stay safe even with other sea creatures.

Did you know...

Sea stars are ocean invertebrates that live in salt water only. Sea stars can be found in the ground of the ocean. They use their tube feet to move around. Sea stars do not have blood in their body. They use sea water instead of blood. Many have often confused starfish with fish. But starfish isn’t a fish, rather a marine invertebrate that has no gills, scales, or fins.

Sea stars have a central disc and tube feet which helps them to catch their target easily.

The starfish or sea stars are available in several colors. They can be found in blue, gray, brown, red, yellow, orange. They are predators with their mouths located at the center of the lower surface along with tube feet. These are controlled by the hydraulic system.

Moreover, starfish species have suspension-feeding as their feeding behavior.

They have the ability to produce sexually and asexually. As a defense mechanism starfish shed off their arm and are able to regenerate from it.

As per some facts, the tiny tube feet invertebrate cannot swim. They pump nutrients instead of blood. Furthermore, starfish have more than one stomach. They have two stomachs – cardiac stomach and pyloric stomach. When the sea stars prey using their tube feet, the food is transferred to both the stomachs. First, the tube feet open the prey’s shell. Then the cardiac stomach is stretched to pull the food in the shell. Finally, the shell contains food and is eaten outside the body of the starfish.

Do starfish have eyes?

Sea stars have eyes located at the end of their arms but they aren’t normal eyes. The ocean echinoderms have eyes that allow detecting shades of light. This allows them to navigate the ocean and hunt for their food. Sea stars have eyes at the end of their arms. Sea stars lack a brain that has caused a doubt whether they can see or not.

Do starfish have hearts?

According to sea stars facts, sea stars don’t have a heart. They are designed in a way that they don’t need blood instead they have a vascular system. They have a haemal system and the vessels form rings around the mouth, around the digestive system, and near the aboral surface. The three vessels in the haemal system of sea stars are the hyponeural haemal ring, the gastric ring, and the genital ring. Their heart-like circulatory beats six times per minute as per sea star facts. Sea stars have very little respiratory function. Some sea stars have no respiratory function in their vessel.

Here at Kidadl, we have carefully created lots of interesting family-friendly animal facts for everyone to discover! For more relatable content, check out these immortal jellyfish facts and jellyfish facts pages.

You can even occupy yourself at home by coloring in one of our free printable starfish coloring pages.



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