THE STEINHART AQUARIUM - Gulf of Guinea Science ...

cementing silk, tough outer silk for the egg
case, soft inner silk in the egg case, and others.
They weave their threads from a liquid,
stored as a gel in the spinning gland. The gel
is a mixture of water-soluble proteins that
turns into a solid fiber when pulled through
structures in the spinning gland, called
spinnerets. Scientist are trying to mimic the
process, using genetically engineered bacteria
to produce the protein gel. They have invented
artificial “spinnerets” where the gel is mixed
with salt water and forced through tiny
channels. While they have succeeded in getting
silk, it was not high quality.
Fishing Spider
Dolomedes okefinokensis (Pisauridae)
Distribution: Swamps in the southeast United
States, particularly southern Georgia and
Florida.
Habitat: Dolomedes spiders live in semi-aquatic
areas.
Appearance: In general, members of the genus
Dolomedes are large (2.5–7.5 cm) and hairy;
most species are brown with a striking pale
stripe on each side. D. okefinokensis exhibit
female gigantism and male dwarfism, with the
male being less than half the size of the female.
Diet: Fishing spiders usually eat aquatic
insects, but they have also been known to eat
small fish and even small frogs. They often
hunt nocturnally, to avoid predators. Like most
spiders they inject venom to kill and digest
the prey.
Reproduction and Development: Females
may eat the males after breeding. This may
help the female have adequate nutrition to
produce healthy young.
Mortality/Longevity: Main predators are birds
and lizards. Dragonflies may also eat young
spiders. Probably live for one season.
Remarks: Dolomedes spiders are covered
in short hydrophobic hairs. This aquatic
adaptation gives them many advantages.
They can use surface tension to stand or run
on water. The air trapped among the hairs
forms a thin film over their bodies when they
descend beneath the water. They breathe with
book lungs that open into the air film, allowing
them to breath under water. The trapped air
also makes them buoyant, and when they
California Academy of Sciences
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release their hold on rocks or plant stems they
pop up to the surface.
While hunting they hold on to the shore with
their back legs and rest their bodies on the
water surface. Fishing spiders have vibrationdetecting
organs on their front legs and feet
that help them identify not only the source
of the vibration, but also the distance and
direction to the source. They feel vibrations
carried in the water, just as other spiders feel
vibrations transmitted through their webs.
SUBPHYLUM CRUSTACEA
CLASS MALACOSTRACA
ORDER STOMATOPODA
(MANTIS SHRIMPS)
Peacock Mantis Shrimp
Odontodactylus scyllarus (Odontodactylidae)
Distribution: Indo-Pacific.
Habitat: Warm waters of bays, lagoons, and
reefs in sand or rubble areas where they build
U-shaped burrows.
Appearance: Beautifully colored in peacock
colors of greens, blues, and reds. Has a green
body, blue head, green antennal scales, red limbs.
The body is elongated with a long, flattened,
blue tail and ranges in size from 3–18 cm. Highly
noticeable is the pair of clubbed-shaped, praying
mantis-like claws.
Diet: Feeds on other shrimp, worms, snails,
crabs, mollusks. Lies in wait for prey in front
of burrow, then swims out and quickly crushes
prey with a strong, powerful smash. The
claw moves through the water so quickly it
generates cavitation bubbles, which explode
with a second powerful burst. The speed with
which the claw moves through the water
generates a force 100 times the shrimp’s body
weight, and is so fast it can only be caught and
measured by expensive, high-speed cameras.
Reproduction and Development: The male
deposits his sperm in a special pouch on the
female’s body and she releases her eggs and
sticks them together in a mass which she carries
by her front legs. The embryos hatch in about
six weeks.