THE STEINHART AQUARIUM - Gulf of Guinea Science ...

usually shed in large tide pools. Following
fertilization, hatching occurs within a day’s
time. Free-swimming larvae settle around 11
days. Mossy chitons attain sexual maturity at
2 years of age.
Mortality/Longevity: A popular treat for
Pisaster ochraceus.
Remarks: A chiton’ shell is composed of 8
overlapping plates that can flex over irregular
shapes of rocks, allowing the animal to create
a tight, secure seal. Most chitons can also roll
into a plate-covered ball in response to danger.
Gumboot Chiton
Cryptochiton stelleri (Acanthochitonidae)
Distribution: Northern Hokkaido Island, Japan;
Kurile Islands, Japan; Kamchatka, Siberia; Aleutian
Islands, Alaska; to the California Channel
Islands of San Miguel and San Nicolas.
Habitat: Low intertidal in areas protected
from strong surf. Also subtidal in kelp forests.
Adults not nomadic; in one study marked individuals
remained within 20 m of the release
site for over 2 years.
Appearance: Length to 35 cm. Dark brown to
“brick” red in color. Mantle thick and leathery.
Diet: Red algae, especially Gigartina spp.,
Iridaea spp. and certain coralline algae; also
green and brown algae.
Reproduction and Development: Spawning
occurs in the spring in California. A gumboot
may lose 5% of its body weight at this time.
Eggs are laid in gelatinous spiral strings up to
1 m long. The laying of this string triggers the
males to release sperm. 0.5 mm larvae hatch
5 days after fertilization. After a 20-hour freeswimming
stage, larvae settle.
Mortality/Longevity: Does not affix firmly to the
rocky substrate like other chitons. Thus is often
washed out of the low intertidal to be stranded
on the high beach during storms. Valves are often
broken, but are able to mend. Has few predators.
The predaceous lurid rock snail rasps pits into
the dorsal surface. Largely ignored by sea otters.
Live to more than 20 years.
Remarks: This species is the largest chiton on
the planet.
The valves of this chiton frequently occur in
historic kitchen middens of coastal California
Native Americans. Exactly how gumboots
were prepared remains unknown. Long,
California Academy of Sciences
53
covered-by-lid slow-cooking over a fire might
be the answer culinary anthropologists seek.
The commensal inhabitants include the
polynoid worm Arctonoe vittata and the pea
crab Opisthopus transversus, which cling to
the chiton’s gills. They feed on plankton and
detritus brought in by the respiratory currents
of the gumboot host.
CLASS GASTROPODA
(SNAILS AND SLUGS)
Red Abalone
Haliotis rufescens (Haliotidae)
Distribution: Sunset Bay, Oregon to Baja
California.
Habitat: Uncommon in the lower intertidal
zone in rocky areas with heavy surf. Most now
in 6–17 m depth in central California.
Appearance: Shell (to 30 cm) is usually brick
red and overgrown with fouling organisms.
Shell’s color influenced by diet. The red color
is from the pigment phycoerythrin consumed
in its red algae diet. Brown specimens eat primarily
brown algae.
Diet: Algae, especially red and brown species.
Drifting pieces of algae are trapped by epipodal
tentacles before the foot traps the plant.
Reproduction and Development: After
spawning, fertilized eggs sink. Half a day
later swimming trochophore larvae develop.
About one day later this becomes a veliger
larva. After a week or two, depending on water
temperature, the larvae settle to the bottom,
metamorphose, and begin to graze. Growth
slows with increasing size and age.
Mortality/Longevity: Mortality is very high
in the planktonic stages. Settled abalone are
preyed upon by sea stars, crabs, octopuses,
fishes, sea otters and humans. Individuals can
live more than 20 years.
Conservation status: Highly endangered.
Due to overexploitation by the abalone fishery,
the population plummeted in the late
twentieth century. Poaching continues to be
a problem.
Remarks: The holes in the shell excrete feces,
urine, gametes and water that has circulated
through the gills.