“It’s moving around. It’s recruiting to new locations ... One of the biggest drivers in bull kelp loss appears to be a boom in purple sea urchin populations. The urchins multiplied around ...

There's a good reason why finding a whole sea urchin fossils is rare, according to Mr Milàn - sea urchins move slowly and are normally eaten by predators, so only small shells are left behind.

and sea urchin spines. Swimming vertically allows the razorfish to hide amongst them, even when moving in large, synchronized schools. Their body color also helps them out here, with those living ...

Warming waters and over-hunting the marine mammals that once brought balance to the ecosystem have led to an overpopulation of Pacific purple sea urchins. And while sprawling urchin barrens sound like ...