Sea Urchins at Axial

Sea Urchins belong to Class Echinoidea (Phylum Echinodermata).

Unknown Sea Urchin 1

This unknown species is relatively common at Axial, living among the basalt lava rocks. Photo credit: NSF-OOI/UW/CSSF; Dive R1731; V14

This is easily the most common sea urchin found on Axial. It is often observed hiding among the lobed basalt lavas. Its size is only 10-15 cm in diameter.

Spiny Sea Urchin (Tromikosoma panamense)

This deep sea, purple spiny sea urchin (possibly Tromikosoma panamense) was seen at the base of Axial. Photo credit: NSF-OOI/UW/CSSF; Dive R1715; V14

The Tromikosoma panamense sea urchin has only been observed on a few occasions, and is not common at Axial. This specimen was seen at the base of Axial Seamount. The T. panamense has a hard armored shell, consisting of small plates covered in spines.

References:
http://www.marinespecies.org/aphia.php?p=taxdetails&id=513622
http://www.mbari.org/benthic/echinoids.html