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20 Facts about Starfish – Characteristics

by Fitriani

Here is a list of 20 Facts about Starfish. Starfish is one of the many unique sea marine creatures out there. With over a thousand species, there is more to starfish than meets the eye. They have interesting abilities and features so read on to find out more.

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1. Provide Shelter

starfishA starfish is a known predator however there is a species of them that actually helps other sea creatures. This species is called the Pincushion starfish (Culcita novaeguineae).

At first glance, the Pincushion starfish may be mistaken for a rock or a coral since it looks nothing like a starfish. Despite the unusual appearance, it is still a species of a starfish.

It provides protection and shelter for sea creatures such as shrimp or pearlfish. This species can be found in the Pacific and the Indian Oceans.

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2. Eyes and Mouth Under the Body

starfishIn cartoons or tv shows, a starfish may be seen as having two eyes and a mouth in the middle part of their body. It is true that they do have eyes but in reality, the eyes are located somewhere else.

The eyes of a starfish are located on each tip of the arms. Therefore, each arm has its own eye. These eyes have a sensitivity for light and darkness which direct them to wherever they want to go.

They help the starfish to navigate through the waters. They do not see things like most other marine creatures do. But they can sense sources of light that will guide them through places.

As for the mouth, it is situated under the body of the starfish. It is in the form of tube feet. A starfish have many tube feet because other than for catching preys, they also help the starfish to move around.

Also read:  Types of Ocean Rays

3. Regenerate Body Parts

starfishWhen starfish lose an arm, it is possible for them to grow it back. When an arm is severed, the main region of the body will receive a signal for the cells to grow it back. It is not known precisely how long it takes for an arm to grow back. It can take six months or a year for the process to be completed.

Also read: 15 Types of Ocean Crabs

Several factors such as food, genes, species and how much regrowing it needs affect the time of the regeneration. An interesting thing about this quality is that some species of starfish may even grow another starfish from its damaged arm. Unfortunately, some starfish may not even have the ability to regrow at all.

4. Switch Gender Whenever they Like

starfishGender is a very interesting fact about starfish. A starfish is either born into a male or a female. However, they can change their genders whenever they please.

So, an adult male may change to a female and then back again to a male if they feel the need to do so. The same thing also applies to the female starfish. Throughout their lifetime, they may undergo hundreds of gender switch. There are many reasons for this gender switch ability.

Read more: Endangered Species in the Atlantic Ocean

One of them is to balance the amount of genders of a specific species. In case there is an overwhelming amount of males and a lacking number of females, some of them may switch to contribute to the female population. This is a great way to pass on genes and helps out a lot in maintaining a healthy amount of the starfish population.

5. Don’t Have Heart and Brain

Short Spined StarfishA starfish also has no heart, just a body full of water imitating a circulatory system to keep them alive. Moreover, they do not have brain. What they do have is a nervous system that is complex but also helps in their instinct to kick in when there is danger.

Due to this, they are spontaneous creature. Instead of planning ahead, they do what feels right at the moment.

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As an example, since a starfish has many arms, each of those arms also have a mind of their own. So if an arm can feel a prey near it, it will be the dominant arm to move the starfish towards the prey.

6. Sunflower Star is the Biggest Starfish

sunflower starfishThe biggest species of starfish is the Sunflower star (Pycnopodia helianthoides). Their arms can amount up to 24. Each of those arm can measure up to more than 100 cm.

The Sunflower star can only live underwater because they will die once they are out of it. They live in the Northern parts of America. Notably Alaska.

Many of them prefer to live in areas where there are many seaweed. They feed on clams, snails or sea urchins. Despite its large size, it is reported that this specific starfish only have the lifespan of around 5 years.

Others Facts About Starfish (7-15)

Below are some additions to the facts of starfish stated above:

7. Starfish Have More than One Stomach

A starfish has 2 stomachs. One is called the cardiac stomach while the other is pyloric stomach. The cardiac stomach can extend, reach food or prey and swallow it. It then passes on the food to the pyloric stomach so digestion can take place.

Read more:Types of Jellyfish

8. Starfish don’t Swim

They move around by using their arms. More specifically, on each of their arms there are small feet called podia. The podia is filled with waters circulated throughout the body. Moreover, the muscles help to expand and contract the arms of the starfish. This is very useful if they want to open scallops or clams for food.

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9. Saltwater is Important to Starfish

A starfish can only live in waters with high concentration of salt. This is due to the fact that they also have a certain concentration of salt in their body. Also they lack the osmoregularity system that enable them to regulate the amount of water and salt in their body. So once they are put out of their habitat and placed into fresh water, they will quickly die. (Read: Types of Ocean Storms)

10. Starfish Can Lose An Arm 

A unique ability that a starfish has is its ability to lose an arm on their own will. This is handy when they are threatened or in danger of a predator. Sometimes they can get caught in the nets of fishermen. But they are able to set themselves free if they can lose an arm or arms that get entangled with the nets. This ability will bring no harm to the starfish since as stated before, they are able to regenerate. (Read: Smallest Dolphins in the World)

11. Starfish Can Turn to Cannibalism

From observations by those who are experts in their fields, it is now known that a starfish can turn into a cannibal. They reportedly may eat their own kinds when there is a lack of food sources. Other reason for the cannibalism is to reduce the competition with the other starfish.

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12. Starfish Undergo Sexual and Asexual Reproduction

There are 2 ways that a starfish can reproduce, sexual and asexual. It can take both a male and a female starfish to reproduce. But a starfish can also produce eggs on their own. In fact, a lone starfish can lay more than 60 million eggs all by itself.

13. Colours and Patterns Help Starfish to Survive

Colours and patterns are important attributes to a starfish. Other than making them look attractive, they also help the starfish to avoid lurking predators. The colour and the pattern of a starfish can help them blend in with their surroundings. Sometimes it’s as if they are a part of the rocks or corals so it can be quite hard to spot them.

Also read: Types of Abalone

14. Starfish are not Fish

Although the name starfish contains the word fish, it does not mean that these creatures are fish. The similarity only holds at the fact that they live underwater. Other than that, they are nothing like fish. They don’t have fins, gills or even scales. Instead of blood, they have water running through their body. Therefore, it has recently been agreed that the name seastar would be more suitable.

15. The Scientific Name of Starfish and the Meaning

The scientific name for a starfish is Asteroidea. Aster means star while eidos means likeness. Put the words together and it portrays the starfish for what they truly are. They resemble the typical image of the stars in the sky. But these ones live in water. (Read: Threats to Marine Habitats)

16. Starfish can Live for a Long Time

The lifespan of a starfish varies depending on their species. However, most of them can live for a very long time. The shortest one is said to be about 5 years. Most starfish can go on for about more than 35 years. A lot of factors can affect their age including exposure to land, food and the overall level of salt of the water they are in.

17. The Starfish Featured in Spongebob Cartoon

Patrick Star from the cartoon Spongebob does exist. The Pink Short Spined (Pisaster brevispinus) starfish is pink in colour and is very, very soft. They commonly have 5 arms and weigh up to 1 kg. They prefer to live among rocks and corals. They must live in water to avoid death.

18. Starfish Begin Reproduction at the Age of Two Years Old

A starfish can begin to reproduce one they hit the age of two years. During the mating season, the female starfish release eggs into the ocean. The male, catching this signal, in turns release sperm. Once they match, a baby starfish is created.

Read more: Largest Clams in the World

19. Not All Eggs from A Starfish Can Survive

Not every egg of a starfish can make it out to be a fully grown starfish. As said before, a starfish can lay eggs if they want to do so. These eggs are released in large amount. However, this large numbers do not indicate that each of them will hatch. Most of them won’t even survive because other creatures will eat them.(Read more: Endangered Species in Pacific Ocean)

20.There are More than 2.000 Species of Starfish

Thus, their appearance and physical attributes differ from one another. Many starfish have visible exoskeletons which make them hard and prickly. On the other hand, there are starfish that have similar texture to that of a leather. Some even have spikes to ward off predators from touching them.(Read: Conservation of Blue Whales)

Starfish indeed contains many surprises and unique abilities to help them cope underwater. These creatures are currently flourishing in their habitat with a healthy amount of population.

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