Arctic Green Sea Urchin
Strongylocentrotus droebachiensis
Sea urchins
sea_urchins_g350
About
Sea urchins are round, spiny animals that sit on the reef or hide in cracks. In this app the group includes the Indo-Pacific rock-boring urchin, the banded sea urchin, and the long-spined sea urchin.
How to tell it apart
You can tell a sea urchin from a starfish by its round, ball-like shape with no arms. To tell members apart, look at spine length and colour, and whether the spines are banded or plain.
Appearance
Sea urchins have a round, hard shell called a test, covered in moving spines. The spines can be long and thin or short and thick, and colour ranges from black and brown to violet and green.
Habitat
Sea urchins live on reefs, sand, and rocky bottoms, from shallow water down to very deep water. They are found in oceans worldwide, often hiding in cracks during the day.
Behaviour
Sea urchins move slowly using hundreds of small tube feet. They avoid bright light and hide in crevices or under objects during the day.
Diet
Sea urchins use five hard teeth around their mouth to scrape and grind food off rocks and reefs.
Breeding
Sea urchins have separate males and females, though they look the same from outside. They release eggs and sperm into the water, where fertilisation happens.
Log it in Into the Blue
Describe what you saw and we name it, then keep every species you find in your Oceandex.
