Tag Archives: Urchins

Whitespotted Toby and urchin

A Whitespotted Toby and a sea urchin in Hawaii

The Hawaiian Whitespotted Toby is a small pufferfish that’s endemic to Hawaii. Like many small fish, and juveniles of larger fish, they will use the quills of sea urchins to shelter from predators. Not that tobies need too much help. When attacked they inflate themselves like a balloon, making them hard to swallow. In addition, this toby secretes a nasty skin toxin which will deter most predators.

Abstracts: Rock-boring urchin art

Channels made by rock-boring urchins in Hawaii

Yesterday I posted a photo of a crown-of-thorns star, with a few rock-boring urchins in it. Today’s post shows one example of the channels left by these urchins. This image initially looked like a brain to me, but then I began to see more of a tree in it.

Posted in response to Becky’s October Squares challenge theme of ‘Past Squares – Spiky/Lines.’ See more responses here.

Crown-of-Thorns star

A crown-of-thorns star and rock borer urchins

I saw this crown-of-thorns star working its way across the rocks in shallow water. Those spiky spines are venomous so this is not something to handle. Also visible in this photo are some equally spiky, though not poisonous, rock-boring urchins

Posted in response to Becky’s October Squares challenge theme of ‘Past Squares – Spiky.’ See more responses here.

Collector urchins and their collections

According to my marine invertebrates book, collector urchins (Tripneustes gratilla) gather algae, shells, and other material on their spines. Why they do this is not entirely clear. It might be for disguise, protection from the light, or even to store food. These urchins are quite common in the shallows and their adornments are many and varied.

Posted in response to Becky’s October Squares challenge theme of ‘Past Squares – Spiky.’ See more responses here.

Signs: Beware of spiny urchins

The beach in front of Four Seasons Resort Hualalai
A sign at the beach in front of Four Seasons Resort Hualalai

I was amused by this sign on the beach in front of the Four Seasons Resort Hualalai. Spiny urchins in the rocks are like white lines on the highway. But of course, a visitor is not necessarily aware of this and the Four Seasons wouldn’t want any of its guests impaling themselves on spiky marine life, especially if they were likely to complain about it later.

This sign wasn’t far from another one that basically said you’d die if you set foot on the beach (here). Perhaps this was why the very lovely beach was deserted when I was there.

Helmet urchins on the coast

This scene drew my attention because of the smooth, round rock nestled into a matching recess in the shore (bottom left in the top photo). It was when I zoomed in (bottom photo) that I noticed the large number of helmet urchins stuck to the shoreline. These cheerful-looking purple blobs live in the harsh tidal zone, and area of crashing waves and surging water. They feed on algae that grows there.

In the middle photo, an a’ama crab skirts a colony of urchins. When the tide comes in, the crab will move to higher ground, but the urchins will stay put, tenaciously defying everything the ocean throws at them.