STARFISH: Everything about this astonishing sea creature

What is Starfish

Starfishes are invertebrates that belong to a group of animals called Echinoderms. There are about 2000 species of sea stars that range in size from less than an inch (2.54 cm) to three feet (1 m) wide. Thus, these sea stars are more commonly known as starfish.

Even with the name starfish, they are not fish. Starfish cannot swim; instead, they use hundreds of tube feet on their body. Also, they do not have gills like fish. Starfish have more than five arms and no backbone. Moreover,they also have the central disc. This is what their arms are attached to. On the bottom of the central disc is their mouth; they only use it to eat. Hence, starfishes also have a spiky shell which offers them protection.

Starfish Scientific name

Starfish’s name is given because of the shape. But its scientific name is Asteroidea.


Starfish classification

Kingdom – Animalia (multicellular organism)

Phylum – Echinodermata (spiny skin)

Superclass – Asterozoa (radial symmetry)

Class – Asteroidea (star-shaped)

Order – Forcipulatida ( forcep like pedicellariae)

Genus – Asterias

Species – Rubens

Starfish characteristics

  • They are radially symmetrical, and the radial symmetry is Penta Mris.
  • Starfishes are marine and benthic animals. Thus, these benthic animals mean they are found on the seabed.
  • Starfish have an oral side, the oral side is lower, and it has an opening in the mouth.
  • The upper side is the Aboral side. It has two main openings, one is the anus, and it has madreporite. Thus, the madreporite is the preface of the water vascular system.
  • Starfishes have calcareous plates, which bulge out a little bit from the skin. Therefore, their upper surface looks a little spiny.
  • They also have pedicellariae on the upper surface. Pedy ciliary looks like forceps that means there are two jaw-like things.
  • Starfishes’ nervous systems are very simple, but they don’t have a brain.
  • They use seawater to pump things around in their bodies. Sea stars can weigh up to 11 pounds, and starfish also depend on the species because some can live all the way up to 35 years old.
  • Starfish are never found in freshwater. They can live at almost any depth of water. They live in cold water near the north and south poles. But, they can also live in warm areas like coral reefs and tropical waters. Starfishes that live in warm places cannot live in cold places, and the same goes with cold water starfishes.
  • Female starfish make millions of eggs; they release the eggs into the ocean and never return to take care of them. Starfish can change their genders at any time.


Starfish habitat

  • Free-living, water-dwelling, nocturnal.
  • Exclusively marine, deep water.
  • Occurs on sandy or muddy bottoms.
  • Crawl over rocks and shells.
  • Move slowly on the hard substratum.
  • All starfishes are carnivorous.
  • They feed mainly crustaceans, polychaetes and mollusks.
  • They also feed on detritus and plankton.
  • Starfish exhibit remarkable power, autonomy and regeneration.

Starfish eating process

Tube feet of starfishes let them move along the ocean floor and open up the scallops and clams. Tube feet help them to find food. Most starfish are carnivores, which mean they are only meat-eaters. Thus, they like to eat mussels from the ocean and mollusks such as clams, oysters and snails. Also, sometimes they eat small fish too. After attaching its body to the food it caught, the starfish spreads its stomach out through its mouths. Moreover, starfish’s stomach releases some enzymes that break down the food. After these foods enter the starfish’s stomach, they can actually eat. They do this because they have two stomachs.


Starfish eating habits

The end of each arm contains an eyespot that can detect light. Thus, Sea Stars are predators and scavengers. Their diet depends on the species and may include invertebrates on the seafloor like bivalves, coral, sponges and urchins. They have a mouth on their underside. However, some species are capable of extending their stomach out of their mouth while consuming prey. They will latch their tube feet onto the shell of their prey. Then pry the shell open just enough for them to reach their stomach inside. It can take several hours for their protruded stomach to digest the prey. Instead of blood, sea stars have a system of water-filled canals called the water vascular system. This system is what enables them to move, feed, and breathe. A plate on top of their body called the madreporite allows water to enter their water vascular system.

Starfish facts

  • Seawater is periodically drawn in to replenish the system. However, most sea stars can regenerate lost arms and willingly shed an arm to escape from a predator. Their hard calcium carbonate skeleton protects them from many predators. But they are still prayed on by animals like birds, crabs, and sea others.
  • Most starfish reproduce by releasing eggs or sperm directly into the water. Fertilized eggs hatch into larvae that drift as plankton before settling to the bottom of the seafloor.
  • Some species can also reproduce asexually by fission or self-amputation of arms. That will grow in a completely new starfish. However, the lifespan of starfish also varies by species, but some can live for decades.
  • In most areas, the presence of sea stars is very important in maintaining the biodiversity of marine ecosystems. Because they prey on animals that could easily become overpopulated, however, outbreaks of the coral-eating crown of thorns starfish can be detrimental to reefs.
  • Every starfish come with the different number of arms. Few starfish looks like a sunflower. This type of starfish has around 40 arms. There are about 2000 species of starfishes.
  • There are different types of shapes of starfishes. Sea stars have a life span of up to 35 years. Because many of their organs are located in their arms, sea stars may regenerate.

Some frequently asked questions

How does a starfish eat?

After attaching its body to the food it caught, the starfish spreads its stomach out through its mouths.

Is starfish edible to eat?

Yes, they are edible to eat.

What does a starfish taste like?

The actual meat of starfish tends to have a reasonably subtle flavour with a slight hint of bitterness. Some people have said that you can taste the saltiness and essence of ocean water in starfish.

Can a starfish bite you?

No, they can’t bite because they don’t have teeth.

Do starfish have teeth?

No, they don’t have teeth.

Do starfish feel pain?

Yes, they feel pain.

How long does a starfish live?

Sea stars may live up to 35 years.

About the author: mike

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