THE STEINHART AQUARIUM - Gulf of Guinea Science ...

88 A Docent Field Guide to the Species of the Steinhart Aquarium
gonads may be 40% by weight in mature Pisaster.
Fertilization external. Free-swimming
plankton-feeding larvae.
Mortality/Longevity: Adults are eaten by sea
otters and seagulls.
“Lucky” individuals of this hardy sea star species
probably live to over 20 years.
Conservation Status: Locally over-collected as
a souvenir of a tide pool visit.
Remarks: Proposed as a “keystone” species
(i.e., structures its ecological community) by
Roger Paine in 1966. Many researchers have
since suggested that Pisaster is “just another
brick in the wall.”
One study showed that less than 2% of the
individuals in three local Northern California
populations were “ochre” in color. When dead
and dry become ochre in color.
Sunflower Sea Star
Pycnopodia helianthoides (Asteriidae)
Distribution: Aleutian Islands, Alaska to San
Diego, California.
Habitat: Common in subtidal regions rich in
seaweeds, but rare in the upper intertidal zones
of rock, sand and mud.
Appearance: Imposing! Up to 24 arms. 40-65
cm diameter. Typically purple, some are yelloworange.
The limbs are soft and flimsy; rough
handling by humans causes arms to be shed.
Diet: Carnivorous. Preferences include purple
sea urchins, mussels, chitons, clams, snails, crabs,
sea cucumbers, polychaetes as well as other sea
stars. Tube feet chemosensorilly “taste” objects
they encounter for edibility.
Reproduction and Development: Fertilized
eggs result in pelagic, plankton feeding larvae.
Mortality/Longevity: The sea star Solaster dawsoni
and the Alaskan king crab eat this sea star.
Remarks: Fastest moving of the stars in our
area, clocking over 50 cm/min.
Largest and heaviest sea star on the eastern
Pacific coast.
CLASS ECHINOIDEA
(URCHINS AND SAND DOLLARS)
Pencil Sea Urchin
Eucidaris tribuloides (Cidaridae)
Distribution: Caribbean, Bahamas, Florida.
Habitat: Coral reef in small crevices, in turtle
grass beds, or under rocks and rubble in back
reef lagoon areas, usually found at less than
50 m.
Appearance: Brown body with thick spines in
all directions.
Diet: Omnivore: algae and small invertebrates
such as sea squirts and sponges. Feeds
nocturnally.
R e p r o d u c t i o n a n d D e v e l o p m e n t :
Sexual reproduction; eggs and sperm are
synchronously shed into the water column
where fertilized eggs develop into free-living
larvae that, after several stages, settle out of
the plankton.
Mortality/Longevity: Life span: up to 5 years.
Remarks: Pencil sea urchins belong to a
primitive sea urchin order, the Cidaroids, the
only kind of sea urchin to survive the Permian
extinction some 245 million years ago. All
modern sea urchins descend from this group.
The spines of pencil urchins, unlike other urchin
groups, are not covered with epidermis. They
are, however, often covered with algae and
epizoans that provide excellent camouflage.
Spines are also covered with barbs that can
inflict serious pain to a predator.
Seek shelter in rocky crevices by day, using the
thick spines to maintain a protected position.
Fire Urchin
Astropyga radiata (Diadematidae)
Distribution: Tropical Indo-Pacific from east
coast of Africa to Hawaiian Islands.
Habitat: Rubble and sand in bays and lagoons.
Appearance: Radially symmetrical with long,
mobile spines usually banded in orange and
white. Five areas free of spines carry striking
red V-shapes with blue spots.
Diet: Herbivore, mostly algae. Active diurnally.
Reproduction and Development: Indirect
reproduction through the release and fusion
of eggs and sperm in the water.
Remarks: This urchin delivers a potent sting
with its spines. Bright colors warn predators
to give it wide berth.
It has a symbiotic relationship with the large
decorator crab Dorippe frascone, which is
known to carry this urchin species on its back.
Commensal shrimp and juvenile cardinalfishes