Community Classroom

Let's Explore the Sea Floor: Sea Urchins

A sea urchin with brown stripes and green spikes.
Author: Olivia Alexander

Have you ever found a sea urchin shell along the beach?

Sea urchins are amazing invertebrates that spend their adult lives crawling along the seafloor with their tube feet. These tube feet extend right out of their calcium carbonate shells and suction to surfaces with their water vascular system. 

We have an abundance of green sea urchins in Deep Bay that can be found in tidal pools and between rocks during low tide. Low tide is when the water level is at its lowest and more of the coastline is exposed to the air. Sea urchins can be found in almost any ocean basin around the world and at any depth!

Their shells are covered in long spikes. Ouch! These spikes help to make them look unappetizing (If I was a fish, I wouldn’t want to eat an urchin!) and they have sensory organs that help them to sense light. Sea urchins don’t like light! They will move away from bright lights to find a nice, dark place to rest.

Sea urchins have mouths. Their mouth is on the bottom of their shell and they have many teeth. They use these teeth to eat anything they can reach! Sea urchins have been known to create Sea Urchin Deserts – wastelands along the seafloor where no plants grow. 

Although they are cute and small, they can have a huge impact on the seafloor! 

Check out our sea urchin talk below or join us on the Deep Bay Marine Field Station’s Facebook page for a LIVE session every Tuesday at 12:30 pm PST. 

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