05/05/2026
In Depth: on the Ocean’s Spiky Survivors
Sea urchins are far more complex than they appear at first glance. These images, captured locally in the Pacific Northwest, show the Green Sea Urchin and the Red Sea Urchin, both of which play a massive role in our underwater ecosystems.
Beyond the sharp spines, here are three facts about their unique biology and impact:
-They see and breathe through their feet. The long, flexible tubes visible between the spines are called tube feet. Urchins use these for walking, breathing, and even sensing light. It is as if they have hundreds of tiny eyes and lungs distributed across their bodies.
-They are essentially "immortal." Researchers determined that Red Sea Urchins can live for over 200 years. Scientists proved this by tracking "bomb carbon" signatures from 1950s nuclear testing found in their skeletons. Unlike most creatures, they do not seem to age biologically; a 100 year old urchin is just as healthy and fertile as a 10 year old.
-They are responsible for a delicate ecological balance. Urchins are the primary gardeners of the sea, grazing on kelp to keep reefs healthy. However, when natural predators like sea otters or sunflower stars are missing, urchin populations explode. They turn into spiky vacuums that can devour entire kelp forests, leaving behind bare rock areas known as urchin barrens.
Nature is a delicate dance where one small creature can completely transform an entire world.
Between the vibrant purple and the lime green, which one do you find more striking?
