(purple) Sea urchins
Purple Sea Urchins, or Strongylocentrotus purpuratus, are spiny creatures that live in kelp beds and on rocks. They are sometimes called the "sea hedgehog" because of their appearance. Green Sea Urchins, or Strongylocentrotus
droebachiensis, are spiny creatures that live in kelp beds and on rocks.
Their name translates from latin into "sea hedgehog", because
of its appearance. A sea urchin can move freely over
surfaces with its adhesive tube feet, working together with its spines. On the
underside of the sea urchin is a centrally located jaw. It is surrounded
by wedges or teeth. Sea urchins eat using these five sharp wedges that come
together like a beak and that are moved by muscles. This beak-like device
allows the urchin to scrape algae off the hard reef coral and rocks.
digestive system
The start- the urchin uses its special jaw, often referred to as Aristotle's lantern, to scrape algae as well as other food off the hard reef coral and rocks. Its then swept into the mouth by its tube feet. Similar to the starfish, its mouth is on the bottom and anus on top of the creature. Once inside the mouth, it is passed to the esophagus.
The intestines and excretion- After being passed through the esophagus, food is sent to the long, winding intestines where it is digested. Waste is then sent out the aboral (top) side through the anus.
The intestines and excretion- After being passed through the esophagus, food is sent to the long, winding intestines where it is digested. Waste is then sent out the aboral (top) side through the anus.