Also known as Sea Stars, let’s dig deeper into the interesting facts about starfish. Most of us have just heard about it in some video or saw the picture in the internet or in the museum or lab. But before judging, let’s see what Starfish are and some facts about starfish.

What family does Starfish belong to?

Starfish is a star-shaped marine fish belonging to the phylum Echinodermata. Same phylum as sea urchins, sea cucumbers, and sea lilies.  There are 7000 species that come under this phylum. They are also known as basket or brittle stars. There are about 2500 species of starfish all around the world.

Facts about Starfish

Where are Starfish found?

As mentioned in the name “Sea Stars” they are found around the sea and seashore where they can feed on their prey. They love to stay around tidepools, seagrass, deep-sea, and kelp forests. Starfish doesn’t seem to love any freshwater environment which is quite odd in marine creatures.

They can live in the sand deep down up to 8000-9000 meters. They are available in all the oceans present in the world, from tropics to frigid polar waters. Starfish resides in an intertidal zone or seashore to deep down abyssal.

What do Starfish look like?

Starfish are marine invertebrates that have five arms and central discs. Their body is arranged around the central axis having five point radial symmetry. There is no right and left half but is the top and bottom side in Sea Stars.

Some species of starfish can have a larger number of forelimb. Most of the species are bright in color, like red, orange, blue, grey, or brown. They have tube feet, and their body gets operated by a hydraulic system, also known as the water vascular system.

Starfish Lifecycle

Starfish have a complex life cycle. They can reproduce both sexually and asexually. Starfish can regenerate their lost parts and also can shed their body parts as a defense mechanism. Echinoderms first got traced in the fossil record in the Cambrian.

Facts about Starfish

Facts about Starfish

Here are some interesting facts about starfish

1. Starfish are brainless and bloodless

Starfishes are one of the beautiful marine creatures. One of the interesting facts about it is, it has no brain and no blood. They don’t have a nervous system to operate their body. They have a single circular mouth that gets connected to each arm via a radial nerve. The neurons present in their body stimulates muscles to each of its tube feet.

Even though they don’t have a centralized brain, starfish have a complex nervous system that makes them feel any pain. They also can plan actions and can use defensive tactics when they sense danger.

The sensory receptors and their setup allow starfish to feel and make decisions regarding their survival, including finding food to avoid danger. They also have eyespot on the tip of each arm that are light-sensitive pigments. These pigments allow them to see and feel light and darkness in the surrounding.

2. Starfish can’t survive in freshwater

Starfish are marine animals as they are born to survive in marine water only. They cannot live in freshwater, but some species of starfish can live in brackish water. They cant survive in freshwater due to changes in salinity.

When they get dropped in freshwater, they cannot resist the unstable state between their body and freshwater. They live in a state of isotonic stability in general. Isotonic balance means to have a balanced amount of water moving between body tissues and saltwater.

3. Starfish diets

Sea star’s diet depends upon the species present in the sea. Many include invertebrates in the seafloor, whereas mostly they depend upon sponges, bivalves, corals, algae, and urchins. Their mouth is on the underside.

Some type of starfish is capable of extending their stomach out of their mouth while consuming prey. They latch their tube feet on the shell of their hunt, then pry the outer cover open just enough for them to reach to the stomach.

They can take several hours to digest their prey. They can digest their food outside the body. Interestingly, starfish can hunt their prey enormous than their mouth. This fact about Starfish is surely ming boggling.

4. Starfish can regenerate

Facts about starfish include the famous ability to regenerate or reproduce their limbs. In some cases, they can even regenerate the entire body. Some species require the central body to be active for regeneration.

Whereas some can form a new starfish from a single or piece of a severed limb. If you cut a starfish radially into five parts, it can regrow or regenerate itself from every five parts and form a new starfish.

Before regeneration, the amputated part or organ must go through a repair phase to heal the wound.

Facts about Starfish

5. Starfish is protected by armor

Starfish have spiky shells that help them to protect themselves from their predators. They have a tough covering on the upper side of their body. The armor got made from plates of calcium carbonate. It also has tiny spines on its surface.

Predators of starfish are sea otters, birds, fish. One starfish having numerous spikes on its upper part is also known as the crown of thorns starfish. The upper surface of some starfish can be smooth as well. Whereas some have overlapping plates and granular roof.

6. Two ways of reproduction

They can reproduce both sexually and asexually. The asexual reproduction of starfish takes fission or through the autonomy of arms. During fission, the central disc of starfish breaks into two pieces. Through those pieces, new missing parts get regenerated.

Asexual reproduction can be releasing lava before maturity. When starfish get plenty of food supply from their surroundings. By doing so, they can ensure more offspring will survive.

Their sexual reproduction is in the form of spawning, where sex cells get released into the water. Male starfish releases the sperm and female releases egg in a vast number. Later, the fertilized embryo becomes free-swimming starfishes.

7. They can have 40 arms

Among 2500 species of starfish, some of them have more than five limbs. They are beautiful marine animals having different colors, shapes, and structures. Some species can even have 10, 20, and 40 arms.

One of the species of starfish known as “Luidia Senegalensis” has nine limbs. They are present in deep water up to 40 meters and around Florida, Gulf of Mexico, Caribbean Sea. They prefer muddy, sandy sea beach locations such as lagoons. These types of starfishes get distinguished or noticed by their number of limbs.

8. Starfish’s habitat is huge

Starfish are adaptable in nature. They can occupy different types of habitat easily if it’s suitable for their survival. Their general habitat includes tidal pools, seagrass, rocky soil, and coral reefs. They can even live in the sand as deep as 20,530 feet without any hesitation.

They aren’t social creatures but can congregate in large groups during certain times of the year for feeding purposes. These animals are available in all ocean basins and a large assortment of depths and bottom composition. However, starfish are benthic animals.

These are some facts about starfish.


(Last Updated On: February 9, 2021)