Nearly 1,000 species of sea urchins1 live in oceans around the world from the intertidal zone visible at low tides to nearly 3 miles depth. They are generally round, covered with spines, and have a hard internal skeleton, or test,2 that protects the urchin’s internal organs. Yes, the skeleton is internal because in life, it is covered with a very thin skin, unlike the true exoskeletons of arthropods like insects.
Informative and humorous, EB.
Thanks, Chris! I’m glad you enjoyed it!
Love this one so much! Sharing!
So much new information for me!
Ball and socket joint…who knew? I think this is my new favorite of all of your posts…Thanks for. All! 🥰👍
Thanks so much, Rae! This was definitely a fun learning experience for me. New respect for urchins!
Fascinating and fun! Who knew the complexity and mystery of a seemingly simple sea urchin? Thanks for this Edwin!
Thanks, Steve! Yes, who knew? I was pretty surprised to learn how complex and interesting sea urchins could be!