Animals

Green Sea Urchin: 21 Facts You Won't Believe!

Read these green sea urchin facts to learn more about this animal.
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The green sea urchin (Strongylocentrotus droebachiensis) belongs to the family Strongylocentrotidae and genus Strongylocentrotus. It is found in the North Sea and the Atlantic Ocean. The range includes coastal areas of Washington and Alaska, western areas or regions of the Baltic Sea, and the coast of Korea. The Strongylocentrotus droebachiensis is known to have a northern distribution and the distribution is not circumpolar. The habitat consists of gravel and rocky areas and they are also found on seafloor bottoms that are sandy. They can also be found around rocky reefs and kelp beds. This species of urchins prefer to inhabit a colder temperature habitat. After several years, these urchins are known to sexually mature or become capable of reproduction. There must be a lot of urchins present for reproduction to happen as it takes place when the sperms and eggs are released together in the water column by the males and females. The diet or food of this species consists of marine life organisms like sponges and marine worms. These urchins also feed specifically on a kind of kelp known as Laminaria. The diet or food of these green urchins also consists of green algae and bull kelp. They also feed on algae and diatoms. The body of this species is covered with short, sharp, and moveable spines. The spines can be purple, brown, or green-tinged. Their mouth is placed on the underside or the underpart while the anus is located on the top part.  They are known to have five teeth and the anus is not covered with spines. Some predators include crabs, lobsters, and seagulls.

Continue reading for more fascinating green sea urchin facts (Strongylocentrotus droebachiensis) and if you are interested, read our articles on jellyfish and brain coral too.

Green Sea Urchin

Fact File

What do they prey on?

Seaweed

What do they eat?

N/A

Average litter size?

100,000-200,000 eggs

How much do they weigh?

1 lb (0.45 kg)

How long are they?

2 in (5 cm)

How tall are they?

N/A

What do they look like?

Green

Skin Type

Shell and calcitic plates

What are their main threats?

N/A

What is their conservation status?

Not Extinct

Where you'll find them

Rocky and gravel areas

Locations

Atlantic and Pacific Ocean

Kingdom

Animalia

Class

Echinoidea

Scientific Name

Strongylocentrotus droebachiensis

Family

Strongylocentrotidae

Genus

Strongylocentrotus

Green Sea Urchin Interesting Facts

What type of animal is a green sea urchin?

It is a sea urchin.

What class of animal does a green sea urchin belong to?

It belongs to the class of Echinoidea of invertebrates.

How many green sea urchins are there in the world?

There is no exact count or specific number of the global population of this species of green sea urchins recorded.

Where does a green sea urchin live?

These marine urchins are found in the North Sea and the Atlantic Ocean. The range includes coastal areas of Washington and Alaska, western areas or regions of the Baltic Sea, and the coast of Korea.

What is a green sea urchin's habitat?

These urchins are known to inhabit waters with colder temperatures. They live in gravel and rocky areas and are also found on seafloor bottoms that are sandy. These urchins prefer water temperatures with a range of 0-15 C (32-59 F).

Who do green sea urchins live with?

Sea urchins, in general, live in clusters and can also be spotted in solitary settings.

How long does a green sea urchin live?

The exact lifespan of a green sea urchin (Strongylocentrotus droebachiensis) is unknown.

How do they reproduce?

The males and females are monomorphic, meaning they are similar in appearance. After several years, these urchins are become capable of reproduction. There must be a lot of urchins present for reproduction to happen. Reproduction takes place when the sperms and eggs are released together in the water column by the males and females. Around 100,000-200,000 eggs are laid or released. After the fertilization of eggs takes place, they are formed into echinopluteus, the swimming larva, and they feed on plankton. Gradually, they mature into adults.

What is their conservation status?

They are placed under the Not Extinct conservation status by the IUCN.

Green Sea Urchin Fun Facts

What do green sea urchins look like?

The body of these urchins are covered with sharp, short, and movable spines. It can have pale green, purple, brown, or green-tinged spines. The mouth, also referred to as Aristotle's lantern, is located on the underside of the body and it is known to have five teeth. The anus is placed on the top side and is located on such a spot that is not covered with spines. Their feet are known to be a thin tube which is filled with water and is long.

The body structure, spines, and teeth of this sea urchin are known to be some of its most identifiable features.

How cute are they?

These sea urchins are not considered cute by people.

How do they communicate?

Not much information is available about the communication of these marine urchins but they are known to communicate using chemical cues.

How big is a green sea urchin?

The average green sea urchin size is 2 in (5 cm) long.

How fast can a green sea urchin swim?

The exact speed of this species of sea urchins is unknown but they are known to crawl on the ocean floor.

How much does a green sea urchin weigh?

The weight of this marine urchin is around 1 lb (0.45 kg).

What are the male and female names of the species?

There are no specific names for the males and females of this species.

What would you call a baby green sea urchin?

There is no particular name for a baby of this sea urchin species.

What do they eat?

Green sea urchins are known to feed on various marine life organisms like sponges and marine worms. It is also known to feed specifically on a kind of kelp called Laminaria. Also, their diet or preferred food consists of green algae and bull kelp. They scrape the rock surface using their mouth, Aristotle's lantern, while searching for diatoms and algae while crawling on the ocean floor.

Are they dangerous?

There have been no adverse effects of sea urchins observed on humans and are not considered poisonous.

Would they make a good pet?

Some people keep sea urchins as pets. They can be kept or placed with saltwater fish and also be used as part of coral displays and live rocks.

Did you know...

Due to their small size, these sea urchins are known to be prone or vulnerable to predators like crabs, flatfish, lobsters, seagulls, and wolffish.

It is believed that these sea urchins help protect some other animals from their predators, by letting these animals hide between their spines.

Strongylocentrotus droebachiensis is known to seek food at night.

If these sea urchins are hit by light, they start pulsing and sending out reds and blues until the light moves away.

It is believed that these urchins are harvested for their roe which is considered a Japanese delicacy.

When one sea urchin is injured, the others move away and return after a short period of time to eat it.  

Can you eat green sea urchins?

Green sea urchins are edible and their sex glands and gonads are known to be consumed.

What is unique about sea urchins?

The spines of these sea urchins are quite unique as they are outside and not inside and between these spines, there are tube feet rows in between that helps this animal to move, find food, collect oxygen from the water, and burrow.

Here at Kidadl, we have carefully created lots of interesting family-friendly animal facts for everyone to discover! Learn more about some other echinoderm from our Irukandji jellyfish facts and crown-of-thorns starfish facts pages.

You can even occupy yourself at home by coloring in one of our free printable urchin coloring pages.

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