THE STEINHART AQUARIUM - Gulf of Guinea Science ...

86 A Docent Field Guide to the Species of the Steinhart Aquarium
invertebrates; also opportunistic carrion
feeders.
Reproduction and Development: As in other sea
stars, fertilization is external. Eggs and sperm are
stored in the rays and released simultaneously.
Larvae look nothing like the adults. The form
that first hatches from the eggs is bilaterally
symmetrical and planktonic. Larvae eventually
settle and transform into tiny sea stars.
Conservation Status: Reportedly common, but
threatened in some areas of their distribution,
such as Singapore. Over-harvested for the
“shell trade” in some localities as a consequence
of their spectacular appearance (however,
coloration fades upon death).
Crown of Thorns Sea Star
Acanthaster planci (Acanthasteridae)
Distribution: The Red Sea and throughout
the Indian and Pacific Oceans, east to Panama.
Habitat: Tropical reefs.
Appearance: Up to 50 cm in diameter, 12–19
arms. Red, with thorn-like spines, which are
toxic.
Diet: Feeds on living coral polyps. Feeds by
extruding its stomach over a coral colony,
releasing digestive enzymes, and absorbing the
liquefied tissue. Each individual feeds alone (at
night), and maintains a constant distance from
other crown-of-thorns starfish. One sea star can
consume up to 6 2 m of reef per year. Can live
without food for over 6 months.
Reproduction & Development: Sexes separate.
Eggs and sperm released simultaneously. Up
to 65 million eggs per spawn. Fertilized eggs
may drift long distances and result in sudden
population booms. This is especially likely in
regions of algae blooms, which may satiate
predators and reduce feeding on sea star eggs.
New sea stars can grow from dismembered
arms, if part of the central body remains.
Mortality/Longevity: Predators include the
Giant Triton (Charonia tritonis), a large sea snail.
Larval or small adults are prey to a species of
shrimp, a species of worm, and various reef
fish, especially the humphead wrasse (Cheilinus
undulatus).
Remarks: Notorious for its destructive effect
on coral reefs. Although it may once have
been a natural force in ecological succession,
populations of the crown-of-thorns starfish have
increased since the 1970s, and it is now at least
partly responsible for much loss of coral reefs,
particularly on the Great Barrier Reef in Australia.
Bat Star
Patiria miniata (Asterinidae)
Distribution: Sitka, Alaska to Baja California.
Habitat: Low intertidal on rocks overgrown with
surfgrass, large algae and sponges. Subtidal to
290 m depth on rocky or sandy substrates.
Appearance: This bat-webbed five-rayed star
may be colored red, orange, purple or mottled.
Arm radius to 10 cm.
Diet: Typically an omnivore or scavenger:
surfgrass, algae, colonial tunicates, organic
films on hard surfaces, as well as other sea
stars. Like most sea stars, feeds by everting its
stomach over prey.
Reproduction and Development: Usually
spawns May to June. Embryos and larvae are
transparent.
Conservation Status: Collecting by tide pool
visitors has diminished some populations, for
example around the Monterey Peninsula.
Remarks: Behavioral biologists (ethologists)
have documented “arm wrestling” between
competing bat stars.
Blood Sea Star
Henricia leviuscula (Echinasteridae)
Distribution: Aleutian Islands to Baja
California.
Habitat: On rocky substrates, especially in
areas encrusted with bryozoans and sponges.
From the intertidal to 400 m.
Appearance: Brilliant red above and bright
yellow below, though may be tan, yellow, or
purplish. Long slender rays. Diameter to 9 cm.
Disc small, arms long and tapering, typically 5
in number, but may be 4–6.
Diet: Uses cilia to feed on suspended particles
of bacteria and microscopic bacteria; may also
feed on bryozoans and sponges.
Reproduction and Development: Smaller
females brood young and release tiny juvenile
sea stars. Larger females broadcast eggs into
the water.
Mortality/Longevity: Predators include birds
and humans.
Remarks: Like all sea stars, has spots at the tip
of each arm, sense organs that are able to “see”