2012 COURSE DATES: AUGUST 4 – 17, 2012 - Sirenian International

Variegated Sea Urchin
Lytechinus variegatus
Rachelle Boucher, Elizabeth Ferrell, and
Samantha Egelhoff
Edited by Caryn Self-Sullivan, Ph.D
& Dr. Bruce Schulte, Ph. D
Ecology & Behavior of Manatees & Dolphins in
Belize, Class of 2010 (contact:
caryns@sirenian.org)
Taxonomy
Kingdom: Animalia
Phylum: Echinodermata
Class: Echinoidea
Order: Temnopleuroida
Family: Toxopneustidae
Genus: Lytechinus
Species: Lytechinus variegatus
Ecology
Commonly known as the green sea urchin,
Lytechinus variegatus is found in waters from
Bermuda to Brazil, including the Caribbean Sea
(Norris 2003). In their adult form, they are
mainly white to green in color, although some
have a pinkish-purple hue. They are covered in
short spines that can regenerate. While their size
usually varies from 1-12 cm, some can grow as
large as 36 cm (Barnes 1982).
Purple Variation of L. variegatus
L. variegatus is normally found in calm, shallow
waters, although they can be found in waters up
to 50m deep (Norris 2003). It feeds on seagrass,
mainly Thalassia sp., by using its tube feet and
Aristotle’s Lantern (Norris 2003). The tube feet
act as an anchor and hold the green sea urchin in
White variation of L. variegatus
place, while the mouth of the sea urchin, known
as Aristotle’s Lantern, which is composed of
strong joints and teeth, can scrape its food off of
rocks or other hard surfaces (Barnes 1982).
Behavior
The green sea urchin reproduces by releasing
unfertilized eggs and sperm into its water column,
where the eggs are fertilized and develop into
larvae (Norris 2003). The larvae undergo a
complex metamorphosis to reach the adult form.
L. variegatus use their spines and tube feet to
cover their exterior with surrounding debris,
serving as protection from predators and the sun’s
rays.
Conservation
In Caribbean reef ecosystems, sea urchins have
the capability of population explosion if one of
their key predators is taken out of the system.
Since their main food source is turtle grass
(Thalassia sp.), a large urchin population can
easily clear out whole patches of seagrass on
which other animals, such as manatees and sea
turtles, depend. However if sea urchins are taken
out of a reef ecosystem, the seagrass patches that
they normally keep under control can grow
exponentially in some reef regions and kill off
fragile corals. Jackson, however, mentions that
Diadema urchins have always been abundant in
their environment since pre-colonization, and
predator control might not even be a factor
(1997).