Collector Urchin (Tripneustes gratilla) – Interesting Facts

Collector Urchin

The Collector Urchin is a type of sea creature, called Tripneustes gratilla. It’s like a small, round animal with many spines sticking out.

Collector Urchins are often found deep in the sea, anywhere from 7 to 100 feet down. They hang out in different parts of the world, like the Indo-Pacific, Hawaii, the Red Sea, and The Bahamas.

The urchins grow pretty big, about 4 to 6 inches in size.

What Do Collector Urchins Look Like?

Collector Urchins have a dark body, often a bluish-purple color. They have white spines and their bases are dark or even black.

Some urchins found at Green Island have spines with orange tips. Some urchins may have completely orange spines, while others have only orange-tipped or totally white spines.

But here’s the thing, this color disappears when the Collector Urchin dies or is taken out of the ocean. It’s also hard to keep this color if you try to preserve the urchin.

What Do Collector Urchins Eat?

Unlike some other sea urchins, Collector Urchins eat all the time, day and night. They like to eat near the bottom of the sea. Their menu includes things like algae, periphyton, and seagrass.

Most of the Collector Urchins like to munch on seagrass fronds. But how much they eat can change with the seasons and how many urchins there are. They eat a lot between November and January.

In fact, one study found they ate up to or more than half of seagrass production during these months. But, over the whole year, about 24% of seagrass production is eaten by the Collector Urchin.

Collector Urchins mainly like to eat types of seagrass called Thalassodendron ciliatum and Syringodim isoetifolium, but they can eat other algae too.

Who Eats Collector Urchins?

Even though they have spines, collector urchins aren’t safe from everyone. They are food for puffer fish, octopuses, and even humans.

Where Do Collector Urchins Live?

Collector urchins live in many different places. They are found in waters from Mozambique to the Red Sea, westward to Hawaii and Clarion Island, eastward to Paumotu, and as far south as Port Jackson.

Collector Urchins have even been spotted at Shark Bay on the west coast of Australia and in the waters of Governor’s Harbor, Eleuthera Island, Bahamas.

When Collector Urchins grow up, they like open sea bottoms with some cover. But when they’re young, they prefer rocky areas to hide.

Why Are Collector Urchins Important to People?

Collector Urchins are important in some areas of the world. For one, they are edible, and sometimes humans eat them. But because of this, they have become less common.

In the past ten years, too much hunting has caused a big drop in the Collector Urchin population.

How Are Collector Urchins Helping in Hawaii?

In Hawaii, Collector Urchins are being used to help control a problem. There’s a type of seaweed called Kappaphycus, also known as ‘smothering seaweed,’ that’s taking over local coral.

So, on January 29, 2011, state aquatic biologists and divers from the Hawaii Division of Aquatic Resources put 1000 native Collector Urchins on a 5400 square foot area of reef in Kaneohe Bay.

The Urchins stay on the reef and do a great job of eating the algae.

How Are the Urchins Grown for This Project?

The urchins for this project were grown at a place called Anuenue Fisheries Research Center. They started with about a million larvae

These tiny creatures grew into 25000 urchins that were at least 0.6 inches in diameter in about five months.

The young urchins had to be kept floating in the water for weeks after they hatched. The plan for the project is to release 10000 to 25,00 urchins each month.

Did you know that Kaneohe Bay is the only barrier reef system in the United States? The alien seaweed was brought to Hawaii for use in things like keeping ice chunks out of ice cream. But when that industry failed, the seaweed got loose.

For a long time, the state used a marine vacuum pump to remove the algae, at one point removing 10000 pounds of it.

In 2009, scientists gathered urchins from other parts of the state and let them loose in Kaneohe Bay.

A year later, they found that the urchins had done a great job keeping the seaweed under control.

Scientific Classification

Scientific Name:Tripneustes gratilla
Also Known As:Collector Urchin
Conservation Status:Unknown

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