Project Description

While diving at Oak Leaf this unusual pale-spined green sea urchin (Strongylocentrotus droebachiensis) really caught my attention.  Usually green sea urchins I notice while diving tend to live up to their name.  The tentacles on this urchin are purple, which is apparently a major factor in the identification of this being a green urchin.  Pale urchins (Strongylocentrotus pallidus) have white tentacles.  The green sea urchin is a herbivore and eats a wide variety of algae.  It’s interesting how the tube feet of this urchin cover much of its surface area.  The green sea urchin can grow to 3.6 inches (9 cm) across, with a range that is circumpolar and includes Japan, as well as northern Alaska to northern Washington.