Echinodermata · echinoderms

Green sea urchin

Strongylocentrotus droebachiensis

Strongylocentrotidae · temperate urchinsIUCN: Not evaluated
Green sea urchin
Photo: Hannah Robinson · Attribution · Wikimedia Commons · resized

A cold-water urchin whose roe is harvested in Maine.

Fun factOverfishing its predators turned Gulf of Maine kelp forests into urchin barrens.

Waters
Northeast US, Northwest Atlantic, Northeast Atlantic, Arctic Ocean, North Pacific
Depth zone
Intertidal shore, Coastal shallows & estuaries, Continental shelf
Diet
Kelp & algae
Size
Test up to 8 cm

Classification

Echinodermata › Echinoidea › Strongylocentrotidae

  1. Kingdom Animalia animals
    • Many-celled organisms that eat other living things for energy (heterotrophs)
    • Cells have no cell walls
    • Most can move at some stage of life
  2. Clade Bilateria bilateral animals
    • Body has a left and right side that mirror each other (bilateral symmetry)
    • Head end with concentrated nerves; three tissue layers
    • Includes about 99% of all living animal species
  3. Clade Deuterostomia deuterostomes
    • In the embryo, the first opening becomes the anus and the mouth forms second
    • Includes echinoderms and chordates
  4. Phylum Echinodermata echinoderms
    • Adults usually have five-part radial symmetry
    • Water-vascular system powers tiny tube feet
    • Skeleton of limestone plates (ossicles) in the skin
  5. Class Echinoidea sea urchins & sand dollars
    • Sea urchins and sand dollars: rigid, rounded shell (test) of fused plates
    • Covered in movable spines
    • Jaw apparatus called Aristotle's lantern
  6. Family Strongylocentrotidae temperate urchins
    • Cold-water urchins with short spines
    • Major grazers of kelp
  7. Genus Strongylocentrotus
    • Species in the same genus are very close relatives and often look alike.
  8. Species Strongylocentrotus droebachiensis Green sea urchin

Closest relatives in the guide