THE STEINHART AQUARIUM - Gulf of Guinea Science ...

nutrition by photosynthesis, thus the upside
down posture that allows algae, which live
on the ventral surface, to receive maximum
sunlight. The rhythmic pulsations create water
flow that carries zooplankton over the tentacles
to supplement the diet.
Reproduction and Development: Reproduce
both asexually (by budding) and sexually.
Conservation Status: Common and
widespread, though pressure from coastal
development along mangrove shallows may
pose a future threat.
Remarks: The sting is relatively mild, but
may create an irritating, itchy rash; especially
sensitive individuals can experience vomiting
and skeletal pain.
Sea Nettle
Chrysaora fuscescens (Pelagiidae)
Distribution: Mostly found along the west
coast of North America from Mexico to British
Columbia.
Appearance: The sea nettle is a giant, semitransparent
jellyfish, with an amber-colored,
swimming bell commonly as large as 30 cm
in diameter, with some measuring more than
a meter. In addition to four oral arms attached
to the underside of the mouth, the sea nettle
has 24 long tentacles around the perimeter of
the bell that extend up to 4 m.
Diet: Carnivorous; feeds on zooplankton, small
crustaceans, comb jellies, fish eggs and larvae.
Sea nettles sting their prey with their tentacles,
which have millions of microscopic stinging
cells that inject toxins to stun or kill tiny
animals. The main oral arms then transport
food to the heart-shaped gastric pouches in
the bell, where digestion occurs. Jellyfish are
prodigious predators; they swim and feed
continuously.
Reproduction: Like any other jellyfish, the
life cycle of sea nettles has both a polyp and
a medusa stage. Sexes are separate; egg and
sperm are broadcast into the surrounding
water during summer. Ciliated larvae develop
in the water column, eventually settling on
a hard surface and growing into miniature
polyps. The polyp lives on the bottom and
survives the winter in a dormant state. During
May through August, the polyp asexually
reproduces tiny sea nettle medusas that bud
California Academy of Sciences
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off and eventually grow into the familiar, large
medusa stage.
Mortality/Longevity: In the medusa stage, sea
nettles live from 2–6 mos, usually perishing in
rough waters or being eaten by predators—
ocean sunfish and leatherback turtles are two
of the most prevalent jellyfish predators.
Remarks: Question: What has no heart, bones,
eyes or brain, is made up of 95% water, and yet
is still a remarkably efficient ocean predator?
(The jellyfish)
Some jellies commute 1,000 m up and down in
the water column daily!
Larval and juvenile cancer crabs may hitch
rides on the jelly, dropping off as the jelly
comes inshore.
Sea nettle stings can result in extreme localized
pain. Fortunately this jelly is not aggressive.
In recent years, tests of a commercially
developed sting inhibitor have shown promise
in reducing the severity and frequency of stings
from sea nettles and other jellies. Reportedly,
the inhibitor is chemically based on the mucus
coating of clownfish, known to protect against
anemone stings.
Sea nettles were first captive bred at the
Monterey Bay Aquarium.
The bell of this and other jellies is called a
“medusa” because, with its long, fringing
tentacles, it resembles the snake-haired Gorgon
Medusa of Greek mythology.
PHYLUM ANNELIDA
Featherduster Worms
Sabellastarte sp. and Protula sp.
Distribution: Indo-Pacific, Hawaii.
Habitat: Mainly tropical marine areas, with
muddy or sandy bottoms.
Appearance: Featherduster worms are sessile
marine segmented worms. They form and
live in tubes, attached to rocks, coral or sand
by their bases. Their plumes extend beyond
the open end of the tube to feed. They have
primitive eyes and will withdraw the plume
if they sense motion. Some species may be
shed their plumes if environmental conditions
are poor.