MARE 250

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MARE 250 Transect Lab Sea Urchin Key
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Echinometra mathaei - rock boring urchin
Description small, light-colored urchin with
short spines, thick at the base and tapering to a
sharp point typically greenish-gray or
reddish-brown. Size usually 4-6 cm but up to 15
cm diameter. Habitat in holes and depressions
on rock in shallow areas. VERY COMMON!
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Echinothrix diadema (black blue-black sea
urchin) Description large urchins with long,
slender, needle-like black spines primary spines
are shorter than the test diameter and banded
light and dark green in young specimens two
distinct sizes of spines. Size up to 15 cm
diameter. Habitat in holes on the reef.
WARNING this species has venomous spines
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Echinothrix calamaris (banded sea
urchin) Description large urchins with long,
slender, needle-like banded light and dark green
spines large spines covered with small
spinelets. Size up to 15 cm diameter. Habitat
in holes on the reef. WARNING this species
has venomous spines
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Echinometra oblonga - black boring urchin
Description small, dark-colored urchin with
short spines, thick at the base and tapering to a
sharp point typically dark purple or black
Size usually 4-6 cm but up to 15 cm diameter.
Habitat in holes and depressions on rock in
shallow areas.
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Diadema paucispinosum (long spined urchin) -
black urchin, thin spines 3 or 4 times wider than
the body
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Tripneustes gratilla - collector urchin
Description black, round urchin with short,
narrow spines often tipped with white or pink
pebbles or shell are often held to the test.
Size up to 10 cm diameter. Habitat common on
reef flats but occurs in a variety of habitats.
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Colobocentrotus atratus - shingle urchin
Description small, flattened urchin with
paddle-like spines dark coloration. Size
usually 4-6 cm but up to 9 cm diameter. Habitat
clinging to wave-swept shores.
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Heterocentrotus mammillatus - slate pencil urchin
Description large, blunt, pencil-thick spined
urchin often bright red. Size up to 20 cm
diameter . Habitat in holes on the reef.