By Josie  January 27th, 2023

All You Need To Know About

Here's all you need to know about them:

There are many mysterious organisms in the world, and sea urchins are one of the most alluring.

They can’t swim and thus spend their lives on the ocean floor.

Yellow Wavy Line
Yellow Wavy Line


The name is derived from the Latin ericius (hedgehog), from the old french herichun.

They got the name because they resemble sea hedgehogs.

Other names include:

1. Sea Biscuits 

2. Sand Dollars 

3. Sea Hedgehogs

The history of sea urchins shows echinoids date back 450 million years ago, in the Ordovician period.

The closest echinoderm relatives are sea cucumbers, as both are deuterostomes.


However, the life expectancy of purple sea urchins is around 20 years; this shows that their life duration varies from species to species.

They are unique marine creatures that could, interestingly, live 15 to 200 years in this world.


The body of this animal is spherical and rigid, having locomotive spines over the shell called tests.

Although they don’t possess a right brain, a neural center appears as a big ring surrounding the mouth.


They are highly sensitive to chemicals, light, and touch.

These small ocean creatures range from one inch to 14 inches (3cm to 36 cm).

Typically they weigh around one pound. But it may vary from species to species.

Weight & Size

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Yellow Wavy Line

Their ideal habitats are coral reefs and rocky ocean floors, where they spend most of their time; this is because they can’t swim.

Some species, like shingles, inhabit the shallow water near the ocean beaches.


As they are omnivores, they feed on marine vegetation such as kelp and algae.

Additionally, they feed on sea sponges, coral, and other sessile ocean creatures.


Did you know that the purple sea urchin has extraordinary endurance and can remain dormant for many years without eating food?

Yellow Wavy Line
Yellow Wavy Line

Humans & Sea Urchins

#1 Scientific uses; they are used to estimate sea acidification and ecological impacts.

#2 Food; Both sexes have gonads known as sea urchin roe, which is used as food, especially Japan.

#3 Folk Tradition; In England and Denmark communities used to imagine the sea urchin fossils as apotropaic symbols

#2 The mouth structure of the sea urchin is unique, so it is nicknamed Aristotle’s lantern.

#1 A mammal’s body symmetry consists of two sections, whereas the sea urchin’s body has five symmetrical sections.

Impressive Facts

#3 Expert zoologists suggest that the whole body is a compound eye that is sensitive to light.

Yellow Wavy Line
Yellow Wavy Line

Swipe up to uncover more knowledge!

Sea Urchins remain mysterious sea-residents, but now you know a whole lot more about them!