Purple urchins, or Strongylocentrotus purpuratus, live in tidepools along the West Coast of North America.
2 of 7
Credit: Claire Fackler, NOAA National Marine Sanctuaries
The urchin's spines help it skewer food and protect itself against predators.
3 of 7
Spawning female urchin
Credit: Dan Griffin
The urchins breed annually around January, February and March.
4 of 7
Credit: Elizabeth Lenz
The urchins start out as free-floating larvae that may swim and feed for several months.
5 of 7
Credit: Eric Sanford
Urchins undergo metamorphosis from a larval form to an adult form.
6 of 7
Credit: Andreas Heyland
Sea urchin larvae turn inside-out as the larvae metamorphose to adults.
7 of 7
Sea urchin genome
Credit: Mount Desert Island Biological Laboratory
Scientists recently sequenced the genome of the purple sea urchin.
Science Newsletter: Subscribe
More from LiveScience
Tanya has been writing for Live Science since 2013. She covers a wide array of topics, ranging from neuroscience to robotics to strange/cute animals. She received a graduate certificate in science communication from the University of California, Santa Cruz, and a bachelor of science in biomedical engineering from Brown University. She has previously written for Science News, Wired, The Santa Cruz Sentinel, the radio show Big Picture Science and other places. Tanya has lived on a tropical island, witnessed volcanic eruptions and flown in zero gravity (without losing her lunch!). To find out what her latest project is, you can visit her website.