- Sea urchins live in the mid-level or low-level of a tide pool.
- Sea urchins eat algae off of hard surfaces.
- Most of the time they eat seaweed.
- Sometimes they eat bits of plants and small animals.
- Sea urchins have hundreds of tiny, tubed feet.
- They have five teeth in the middle of their back side.
- Sea urchins use these teeth to pull, tear and rip off algae on the
rocks.
- These teeth continue to grow throughout the sea urchin's life.
- A sea urchin's size is about 4 inches
- They come in many different colors. The most common are purple and
light pink.
- Spherical-shaped echinoderm with movable spines covering the body.
- The body wall is a firm, globose shell or test, made of fused skeletal
plates and marked by regularly arranged tubercles to which the movable
spines are attached.
- Five rows of the skeletal plates are pierced by pores for the tube
feet of the water-vascular system; these are typical of echinoderms
and are used for locomotion.
- The mouth is centered on the lower side of the body and in many species
is surrounded by a whorl of gills.
- A complex jaw and tooth apparatus in the mouth, known as Aristotle's
lantern, is used to fragment food.
- Long, sharp spines are used for protection, and in some species are
poisonous.
- The spines are also used as levers, aiding the tube feet in locomotion
and, along with the teeth, are used by some species to dig burrows in
hard rock.
- Sea urchins feed on all kinds of plant and animal material; some eat
sand or mud, digesting out organic material that is present.
- Entirely marine, they occur in all seas and at all depths but prefer
shallower waters and rocky bottoms.
- Sea urchins are classified in the phylum Echinodermata, class Echinoidea,
subclass Regularia.
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