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Regular echinoids
are almost exclusively epifaunal, living on the surface of the
sea floor. A few species bore into rock surfaces thereby excavating
themselves a home, and in some cases may even become trapped
inside their burrow as they grow. Very few species can tolerate
exposure at low tide, even for a short time. Regular echinoids
feed using their lantern, rasping encrusting plants and algae
from hard substrates or grazing on plants and sessile organisms
such as sponges. Spines are used for defence and for locomotion,
while the tube-feet are used primarily for adhesion, manipulation
of larger particles, and for respiration. Although there are
some species that are short-lived, surviving for only about a
year, many live much longer, and some can reach as much as 15
or more years. They reproduce by shedding eggs and sperm into
the water column. The sexes are separate but can rarely be distinguished
from external appearance.
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Regular echinoids
can be keystone taxa in shallow marine communities as one of
the dominant algal grazers. When populations have been lost through
disease or overfishing, algal stands thrive and the nature of
the sea floor can become drastically altered. Regular echinoids
have many predators, including species of fish, sea otters, birds
and crabs.
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