The purple sea urchin (Strongylocentrotus purpuratus) is a conspicuous native of rocky intertidal habitats along the western coast of North America. These spiky animals live in rock pits, which are safe havens from the pounding surf and scorching sun. Unlike their hermit crab neighbors, purple sea urchins build their homes themselves by boring holes into the rock using their powerful five-toothed jaws. However, like hermit crabs, their homes must grow with them, so these urchins make expanding their pits a lifelong project. This boring task spans across generations—eventually, new sea urchins will call these pits home and take up the mantle. Their rocky relationships don’t just stop there: they frequently pick up rocks and other debris from their habitat. This peculiar home decor is thought to help protect them from the sun’s radiation and predators. Next time you’re out on the coast, make sure to say “Hi” to our local amateur geologists—but watch out, they can have a prickly personality!
Below: (Left) A group of purple sea urchins and their pits; (Right) A purple sea urchin holding some rocks.
Photos and caption by Andrew Moura
Edited by Brady Nichols
theethogram.com 