Unbelievable Facts About Urchins

14/04/2023

14/04/2023

A species of sea urchin was discovered through eBay!

In 2006 British marine biologist Dr. Simon Coppard came across an urchin for sale on eBay that he had never seen before.

He was aware of the species existence since 2004, when a group of budding shell collectors had been discussing online, sightings of the brightly colored urchin.

Coppard was working with The Natural History Museum in London in the department of identifying and naming new species.

He was able to confirm from the photo uploaded onto eBay that the species was unidentified, making it a new discovery of sea urchin.

After his discovery was published, he was approached about naming the new species.

It was given the scientific name Coelopleurus Exquisitus also known as The Exquisite Urchin.

This name was given because of its natural beauty and bold colorful patterns.

14/04/2023

Urchins make for a tasty snack, not just for animals but humans too.

Not only are there species that eat the parasites off of the urchins, but there are also animals that eat them whole!

Sea urchins have quite a few predators which is surprising given their spines and sometimes venom.

The sea otter is one of their biggest predators; they will eat as many as they can get their hands on.

Some of the most common predators are crabs, large fish, eels and even birds.

Urchins also have the threat of humans, urchin and in particular their row (eggs) are seen as a delicacy in many places.

This threat has caused a large decrease in the population and has caused some species of sea urchins to become endangered because of overfishing.

14/04/2023

It is possible for some fish to build up immunities to the flower urchin’s venom.

The clownfish is one of the only species that purposefully try to build immunity to the flower urchin’s venom.

Clownfish will dance around the flower urchin, lightly brushing itself against the spines.

This means they are exposed to a small amount of venom, but not enough to kill them.

After repeating this a few times they become immune to the venom.

You might be wondering why they choose to do this and the reason is so they can eat the parasites that live on the flower urchin.

This relationship is beneficial to both creatures as the clownfish gets food and the flower urchin has its parasites removed.

13/04/2023

The flower urchin is the most dangerous in the world.

Toxopneustes pileolus, known to most as the flower urchin is the deadliest of all.

As described in Guinness Book of Records, the flower urchin contains deadly venom, which can kill a human.

Its venom contains two poisonous elements; Contractin A, which can cause red blood cells to clot and can cause muscle spasms.

The other element is Peditoxin which can cause anaphylactic shock, convulsions and death.

When a human or animal steps on, touches or brushes past the flower urchin, its “flower-shaped” spines will break or pierce the skin of the predator.

This means that the venom can then enter the bloodstream.

Although they are a threat, with adequate treatment, you will survive a sting.

The flower urchin is most commonly found in the Indo-West Pacific region.

09/04/2023

Protected by those who came before you?
This Green Urchin is using a piece from a dead urchin's test (shell) as protection. This piece is from a larger urchin species - a Red Urchin or Purple Urchin.

Protection? From what?

See below for information I have provided in previous posts about urchins covering themselves with bits of shell, rocks, algae, and even shells with hermit crabs still living in them.
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I most often see this covering behaviour by smaller Green Urchins in the shallows (5 metres depth or less).

Urchins move the bits by passing them along their tube feet - from one little suction cup structure to the next. They also use the tube feet to hold onto the pieces and to move themselves around. The tube feet are the brown structures in this image.

Why cover yourself when you already have such great defences as an urchin ? Defences: (1) spines; (2) structures called "pedicillaria" that can nip away at the tube feet of sea star predators; and (3) being able to move away with your tube feet and spines.

Some researchers hypothesize that the debris provides defence from predators by providing "visual and/or tactile camouflage" and possible shielding. But the covering will also impede your ability to get away and feed.

Other research (on a different urchin species) found that the presence of predators did not impact whether the urchins covered themselves or not. Rather, it appeared that they were more likely to cover themselves in areas with more wave action and when there was more contact with sweeping fronds of kelp. It also appeared that smaller urchins were more likely to cover themselves and that exposure to UV light was a stimulus as well.

From Dumont et al 2007: "Juveniles showed stronger covering responses than adults, possibly because they are more vulnerable to dislodgement and predation . . . Our observations suggest that the covering behaviour . . . has evolved as an adaptation to protect it from mechanical injuries associated with abrasion and dislodgement, and to a lesser extent as a defence against UV radiation."

Photo: March 12, 2023 NE Vancouver Island in 'Namgis Territory ©Jackie Hildering, The Marine Detective. Depth was around 6 metres.

09/04/2023

They have zero bones in their body.

Unlike humans they don’t rely on a bone structure to support their bodies.

Urchins have a shell-like structure which is called a “test”.

The hard shell made from calcium carbonate is similar to that of starfish and sand dollars and is their main form of protection.

The structure consists of small plate segments that enclose the urchin; it looks a bit like the segments of an orange.

As well as the “test” they have spines which help them protect themselves from predators.

03/04/2023

The red sea urchin is the largest of the species.

In general sea urchins grow to be around 1.18 inches (3 cm) to 3.93 inches (10 cm).

The red sea urchin is the biggest of the species and it will enter adulthood when it reaches 1.96 inches (5 cm) in diameter.

It will then continue to grow until it reaches around 3.93 inches (10 cm), whereas most other sea urchins will stop growing around 1.96 inches (5 cm).

The red sea urchin can be found in the North Pacific Ocean, from as far north as Alaska, to as south as Baja, California.