Starfish Facts ~ Starfish FAQ

by Orma Editors

in Sea Life, Starfish

What is the widest starfish?
The Giant Sea Star is the widest, reaching up to 3 feet in diameter.

Largest Starfish Giant sea star

Largest Starfish Giant sea star

What is the heaviest starfish?
Thromidia gigas (only name for it) can reach 13 lbs, so it’s the heaviest starfish in the world.

Heaviest Starfish Thromidia gigas

Heaviest Starfish Thromidia gigas (From Dave Lane on the Santo 2006 Expedition)

What is the smallest starfish?
Patiriella parvivipara are less than half an inch.

Do starfish have eyes?
They have a primitive eyes called an eyespot. Eyespots were the the predecessors to our complex eyes. Eyespots can only discern light and dark and on the starfish, they are located on the tip of each leg. Look carefully at the tip of a leg and you might notice a red or black dot- that is the eyespot.

Starfish are Echinoderms
They are related to sand dollars, sea urchins, and sea cucumbers.

Are there freshwater starfish?
No. Like Octopuses, they are only found in sea water.

How many species of starfish are there?

Do starfish have any blood?
No. They rely on seawater to pump up their legs.

What’s the plural of starfish?

What do starfish eat?
Anything they can catch but mainly clams, mollusks, some coral and dying fish. They eat clams and other shelled creatures by prying the shell open and then inserting their stomach to digest the critter on the spot.

Why do starfish lose their arms?
When they are threatened or grabbed by a predator, such as a crab they will sacrifice the arm that’s being grabbed or simply drop one as a distraction while they try to escape.

How long does it take a starfish to regenerate a lost arm?
About a year.

What happens to the lost arm if it is not eaten or damaged?
It can grow into a new starfish as long as some part of the central ring is included.

Are starfish poisonous?
Yes. There are many species of starfish that are poisonous and even deadly to humans. The crown of thorns, the sun star, the spiny sun star and the leather star are some of them. Their spines are the poisonous parts.

Deadliest Starfish

Deadliest Starfish – Crown of Thorns starfish

What’s another name for starfish?
Sea star

Do starfish have a front or back?

Do starfish have brains?
They do no not have a centralized brain but instead a network of nerves that simply reacts to its environment. The central nervous system of a starfish consists of a radial nerve running the length of each ray and a circumoral (“around the mouth”) nerve ring that connects the radial nerves. Contrary to what you might expect, the nerve ring doesn’t seem equipped to do any kind of processing of information. Instead, all the sensory information must go to the radial nerves, any memories must be stored in the radial nerves, and any decisions about what to do must be made in the radial nerves. And somehow, the five different radial nerves must coordinate those decisions if the starfish is going to get anywhere.

The best theory is that some sensory information is shared between the different rays (it is unclear how much, or how far it goes), and that the rays can inhibit each other — that is, one ray can take charge of the whole starfish for a time. When moving, this seems likely to be the arm in front of the starfish. When trying to locate an odor, the ray sensing the odor most intensely seems to be the one which takes charge, directing movement in its own direction. 1

They have no capability to plan anything. It’s all reflex.

What is the starfish reproduction process?
They gather in groups. Females release their eggs( gametes) and males release their sperm into the water and by chance they meet up and then the starfish lifecycle begins.
Some starfish reproduce by losing part of an arm which will then grow into a new starfish.

What is the life cycle of a starfish?
They start life as embryos then become bipinnaria, then brachiolaria. They are still relying mainly on their egg yolk sac for survival and are floating with the surface plankton. When of sufficient size, they drop to the seafloor and continue growing into adulthood.

How long do starfish live for?
Their lifespan ranges from 5-35 years

What is the scientific name for starfish?

Where can you buy a starfish?
Most salt water fish stores carry them. Some Petco’s do as well. Chocolate chip starfish are commonly kept as pets.
Here’s one being fed shrimp:

Are they difficult to keep as pets?
No. Here’s a Petco’s care sheet.

Do starfish have a heart or circulatory system?
Starfish do not have a true circulatory system. An extension of the stomach known as “pyloric cecum” extends throughout each of the arms of the starfish and supplies nutrients to all parts of the body. Thus, starfish do not need a true circulatory system.Starfish also have no true heart or anything that more than merely resembles a circulatory system. Starfish have a well structured system of tubes that works in lieu for the circulatory system.2

Are starfish edible?
Yes. In Japan they are considered a delicacy.

Starfish on a Stick

Starfish on a Stick

Are starfish asexual?
They are asexual in the sense that they can reproduce by regeneration from a fragment of an arm but they don’t typically reproduce asexually instead relying on the traditional egg/fertilization method.

Are their male/female starfish? 
Yes, but you have to dissect them to tell whether they are male or female.

Are there any endangered starfish?
No. None on the IUCN Red List

Do starfish have a mouth?

Do starfish have teeth?

Do starfish bite?

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{ 11 comments… read them below or add one }

lori February 22, 2014 at 4:10 pm

Why do star fish have reproductive parts and digestive glands in each of their 5 arms?


cat October 13, 2013 at 6:46 pm

Where do sea stars actually live?


Ang Ang October 11, 2013 at 5:17 pm

Amazing site for a Friday night. Just shared this on Facebook. Starfish or as they are properly known ‘sea stars’ really should be more popular than they currently are. Does anyone know where I can buy some? Would they live in a garden pond?


Dude September 26, 2013 at 9:20 pm

how does a starfish protect itself from other sea creatures?


anabel June 18, 2013 at 9:29 pm

were do you mostly find starfish in the ocean


Belle May 14, 2013 at 5:15 pm

They shouldn’t be referred to as “star fish” because they aren’t fish. Seastar is the proper name.


tay May 13, 2013 at 8:38 pm

do star fish manage its body temperature


tay May 13, 2013 at 8:37 pm

do star fish have hearts


Chasity May 10, 2013 at 9:13 pm

I wonder what is a starfish life cycle


jimmy April 7, 2013 at 2:54 pm

what happens if you put a dried up starfish back in the water


ashley March 27, 2013 at 6:47 pm

i think this a really good site because i never knew that starfish didn’t have any blood i thought they did.


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