Michael Bryan

Written by Michael Bryan

Modified & Updated: 13 May 2024

Sherman Smith

Reviewed by Sherman Smith

Starfish facts

Starfish are beautiful marine animals found in a variety of shapes, sizes, and colors. As of the moment, there are no starfish species that are endangered. Though that definitely sounds like good news, according to the reports, starfish’s numbers are rapidly declining. So, let’s get to know more about them in these starfish facts and how we can protect them.

  1. Starfish as also known as sea stars.
  2. Starfish does have a brain.
  3. They also don’t have blood and a heart.
  4. Instead of blood, they have a water vascular system. That system pumps seawater through the tube feet and throughout the starfish’s body.
  5. Starfish use filtered seawater to pump nutrients through their nervous system.
  1. The scientific name of starfish is Asteroidea.
  2. There are more than 1,500 species of starfish.
  3. The most common species of starfish are the five-arm varieties.
  4. The other species of starfish have 10, 20, and even up to 40 arms.
  5. Starfish are often found from the seashore down to the deep parts of the ocean.
  6. Starfish can live 6,000 meters or 20,000 feet below the surface of the ocean. That is around 20 times of Eiffel Tower’s height.
  7. Many species of the starfish are brightly colored in different shades of red or orange, while others are grey, brown, or blue.
  8. Starfish can’t swim. However, they can move along the seafloor or on reefs by an unusual process of locomotion.
  9. Starfish moves by using its tube feet that are present under its body.
  10. Starfish can move with an average speed of 15 cm or 6 inches per minute.
  1. The upper surface of the starfish can be smooth, spiny, or granular.
  2. Starfish or sea stars don’t have a backbone.
  3. There are no starfish in the freshwater and they can’t live there as well.
  4. Starfish are related to sea urchins and sand dollars.
  5. It is estimated that starfish first or sea stars exist around 450 million years ago.
Table of Contents

Starfish Facts Infographics

Starfish Facts Infographics

Starfish is not a fish.

According to experts, starfish don’t fall in the classification of fish thus, they prefer to call it “sea stars.” Although they lived underwater, they do not have fins, gills, or scales like fish do. Also, the starfish move differently from fish, they have very small tube feet to support them move along.

Starfish or sea star is an echinoderm.

Starfish are classified as echinoderms which are exclusively marine animals. An echinoderm is a marine invertebrate (an organism that doesn’t have a backbone) that has spiny skin.

starfish facts
Photo by Poseidon X on Unsplash

Corals and clams are the primary food of starfish.

In general, starfish feed on coral, clams, sand dollars, oysters, mussels, algae, and sponges. Furthermore, other species of starfish also eat injured fishes in the ocean if there is a given opportunity. In other words, they are also carnivores.

Starfish eat in a very unique way.

A starfish has its mouth at the center of its lower surface. It uses its feet, which have suction cups on the bottom, to help it hold on to its meal. When it is feeding on a clam or an oyster, for instance, it uses its feet to open it up. Once it is opened, the starfish’s stomach goes out of its mouth and pushes itself inside of the mussel shell or clam.

Starfish can reproduce both sexually and asexually.

Starfish also have a unique life cycle and they can reproduce both sexually and asexually (a type of reproduction that does not involve the fusion of gametes).

Starfish's fertilization happens in the water.

In sexual reproduction of the starfish, fertilization happens in the water with females and males releasing sperm and eggs into the environment or much known as “free spawning.” The sperm and egg will float until they meet up and fertilize accordingly. Furthermore, asexual reproduction in starfish takes place by fission or through autotomy of arms.

Starfish can regenerate their damaged parts.

Most species of starfish have the ability to regenerate their damaged parts including the regeneration of lost arms. Hence, they can “sacrifice” their arms as a defense mechanism.

They can live up to 35 years.

The average life span of a starfish or sea stars is 35 years. Although in general, the bigger starfish species tend to live longer compared to their smaller counterparts.

starfish facts
Photo by Matthes Trettin on Unsplash

Starfish can live in a saltwater aquarium.

Starfish pet owners should know that they are grazers and eat food that has fallen to the bottom of the aquarium or fish tank. Most species like a meaty diet such as clams or mussels since it’s their natural food. Above all, starfish should be kept in the saltwater aquarium along with the proper tank maintenance.

There are square starfish.

One of the most uncommon species of starfish is the square starfish which was discovered in Mathesons Bay, New Zealand, mesmerizing its visitors, as well as marine biologists.

Starfish can feel pain.

Although starfish don’t have blood, heart, and brain, in contrast to the belief of many, starfish can feel pain or get hurt because they have a complex nervous system.

Starfish are generally edible.

There are different opinions about the taste of starfish. Some people argue that it tastes like river crabs or sea urchins, while others say that it tastes nothing. Starfish delicacies are served in sometimes in sushi restaurants or even just in the streets like in Bejing, China. Here’s the video if you’re up for some yummy starfish facts. (Well, actually we’re not so sure ourselves if we want to try that.)

Starfish or sea stars have eyes.

Though it is not obvious, they do have eyes. Starfish have eyes on the tip of their arms. Each of their arms has an eye that looks like a red spot. These eyes cannot see full details but can sense dark and light which is suitable in their environment.

Starfish have a protective shield.

Commonly, a starfish has a hard covering that may feel leathery and sometimes thorny depending on the species. The composition of starfish or sea stars’ skin is a calcium carbonate plate with little spikes. This serves as their protection from predators such as sea otters, birds, and fish.

Some species can survive out of the water for about 28 hours.

Although there are times that we can see starfish on the shore or attached to rocks and pilings during low tide, they can’t stay out of the water for a long period. Most species of starfish can go out of the water for a short period without harm and the larger species of them can survive out of the water for about 28 hours.

Read on for more starfish facts about their different species.

Pink starfish is one of the largest starfish.

pink starfish, starfish facts
Photo by Jerry Kirkhart on Flickr

The pink starfish, also known as short-spined sea stars or giant pink sea stars are species in the Northeast Pacific Ocean. William Stimson introduced it to science in 1857. The pink starfish are big with five thick arms. Its typical size is 13 inches in diameter. However, some could grow up to 35 inches in diameter and can weigh up to 4 kilograms. The color of it is usually pink but sometimes with grayish shadings.

Royal Starfish live around 70 to 100 feet deep in the ocean.

The Royal Starfish is a brightly colored species of starfish. This species is found along the east coast of North America, mainly in the southeast. Normally, Royal Starfish live around 70 to 100 feet deep in the ocean but they can go deeper more than 600 feet and feasts on mollusks (soft-bodied invertebrates of the phylum Mollusca). In contrast to other species of starfish, the royal starfish eats its prey whole.

Bat Starfish got its name from its webbed arms.

Bat starfish, starfish facts
Photo by Jerry Kirkhart on Wikimedia Commons

This species of starfish has many names such as bat sea star, webbed star, sea bat, or broad-disk star. This interesting starfish got its name because of its similar look with bat wings where the arms have webbing in between. Normally, the bat starfish have five up to nine arms. Its color ranges from orange to purple to green. You can find this species along the West Coast of North America, from Baja to Alaska.

Nine-Armed starfish is the only species to have a name after its nine arms.

Nine armed sea star, starfish facts
Photo by Andrea Westmoreland on Wikipedia

Although it may not be the only starfish to have nine arms, it earned its name. This species in the West Atlantic Ocean is a scavenger and feeds on small shellfish, mollusks, and sea worms. The nine-armed starfish swallows most of their prey whole using its stomach.

The largest starfish is the sunflower starfish or sunflower sea stars.

These huge species in the Northeast Pacific Ocean have arms that can reach a length of 1 meter. They have 16 to 24 arms with powerful suckers. The sunflower starfish have a wide variety of colors such as bright orange, yellow, red to brown, and sometimes to purple. They mostly feed on snails, sea urchins, clams, and other small invertebrates.

If you enjoyed these starfish facts, don’t forget to share them with your family and friends!

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