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BONELESS BEAUTIES
Drastically different in appearance, the creatures found in this exhibit all have
one thing in common, the lack of a backbone. Scientists extimate that more than 95%
of all known species on earth are invertebrates. These animals represent a vast array
of shapes, sizes, colors and characteristics from the microscopic rotifers at .00004 of an
inch to the giant squid growing to more than 60 feet in length. The Boneless Beauties
gallery offers close-up views of some of these fascinating animals including giant
Pacific octopus and giant spider crabs to the delicate moon jellyfish.
A new addition to this exhibit located at the entrance to the Undersea Cavern
opened in May 2009 called Jellies: Living Art.
Giant Pacific Octopus
Enteroctopus dofleini
An Octopus is an invertebrate that has a
soft body, eight arms each with two rows of
suckers, a well developed brain and two complex eyes. They belong to the phylum Mollusca
and are relatives of squid and the chambered
nautilus. There are nearly 289 species of octopi
in the world. The giant Pacific octopus (GPO) is
the largest species in the world. These giants may weigh several hundred pounds and
have an arm span over 30 feet. This species is found in the Pacific Ocean from southern
California along the coast of Central and South America, the Aleutian Islands and
Japan.
The lifespan for a giant Pacific octopus is quite short, only 3-5 years. One of the
arms of the male octopus is called the ligula and is used during mating. Males may
mate with more than one female and females receive fairly large spermatophores (up to
1 m long) during mating. Females lay eggs on the inner side of a rocky den and may lay
20,000 to 100,000 eggs over a period of several days. Eggs are tended, cleaned and
aerated by the females until they hatch. Incubation takes five to seven months.
Females do not feed while tending eggs and may die shortly after the eggs hatch. The
young drift among the plankton for about one month. They then settle to the reef below.
Octopi utilize dens as both a brooding chambers and as refuges from predators. Dens
may be naturally occurring spaces in rocks or reefs or may be constructed under ledges
or overhangs.
Mature females have 2240 suckers, 280 on each arm. The males have fewer
suckers because there are only about 100 on the modified arm used during mating. The
octopus uses the suckers to help detect its prey. Octopi eat crustaceans and mollusks,
most often small crabs and scallops, snails, fish and even other octopi. Octopi use their
arms to pull apart the shells of bivalves. They also may secrete a substance that softens the shell to allow the octopus entry. The octopus will then inject a toxin through its
beak that helps to dissolve the prey making it easier to ingest.
The body of an octopus is called the mantle. The mantle houses the stomach, the
hearts and other body organs. An octopus has three hearts that pump blue blood. Two
of the hearts work along with the gills to pump blood through the gills. The third heart
pumps blood throughout the body.
The giant Pacific octopus has the ability to dramatically change its color to blend
into the algae or other reef structure. They change color in response to predators or
other disturbances. Octopi defend themselves by expelling a jet of ink through its
siphon into the water while it exits the other direction. They also pump water through
their siphon as a means of jet propulsion.
Octopi are considered to be the most intelligent of all invertebrate animals,
comparable to the house cat. They are often secretive yet curious and will explore their
environment and whatever is in it. Octopi are often difficult to keep in collections as
they tend to be excellent escape artists and securing them in their tank proves to be
challenging. Aquarium staff uses astro-turf to surround the inside ledge of their exhibits. Their suction cups can not adhere to this material thus preventing them from
climbing out. Most of our octopus come to the Aquarium from Living Elements in British Columbia.
Giant Spider Crab
Macrocheira kaempferi
The phylum Arthropoda
contains the largest number of
creatures on the planet. The
largest among them is the giant
spider crab. The word arthropod
means “jointed legs” and the
crabs certainly have plenty of
legs, 10 in all. Two legs are modified into large claws. Their body is round and may
grow to 15 inches in diameter while their leg span may reach 12 feet. These crabs have
two large claws called chelipeds that grow larger in males than females. Like other
completely aquatic animals, spider crabs breathe using gills located under their carapace. They are covered with stubby projections (tubercles). Adult males can weigh up to
40 pounds.
Giant spider crabs are found in the Pacific Ocean near Japan living in vents or
holes at depths of 100-165 feet. The Japanese name for these crabs is Takaashigani,
meaning the tall-leg crab. This species is omnivorous and often scavenges along the
bottom in search of food. Some pick at the floor of the ocean for plants and algae, while
others pry open the shells of mollusks to eat the fleshy meat. As they grow, crabs must
molt their exoskeleton, a process that can leave them vulnerable for a short time.
Spider crabs reproduction begins with the male transferring a sperm packet, or
spermatophor to the female. After fertilization, the female crab carries the eggs attached to the abdominal appendages. Upon hatching, the young do not resemble their
parents, but instead are small organisms with round, legless bodies. The crab molts
several times as it grows and as soon as its legs form, it is said to be in the megalops
stage. Molting will continue until the crab resembles its adult form. Their life span is
thought to be approximately 20 years.
Although this species is the largest crab, it still must be protected from other
larger predators, such as octopi. For camouflage, it attaches sponges and other similar
animals to its shell. Although it is difficult to catch because of the depth it prefers,
giant spider crabs are collected for food in Japan. The original spider crabs came to the
Aquarium from Blue Corner Japan, Inc. in Shizouka, Japan.
Pharaoh Cuttlefish
Sepia pharaonis
Often called the “chameleons of the sea,” the
cuttlefish is a master at color transformation.
These invertebrates used cells called chromatophores to rapidly alter their color. Cuttlefish
have sucker-lined appendages growing
from their head, eight arms and two
retractile tentacles. Like the octopus,
cuttlefish have large and complex eyes
that focus by changing the shape of the
eyeball. Cuttlefish have a chalk-like
internal shell called a cuttlebone that
helps give shape to the body or mantel. The cuttlebones are not really bone, but instead are made of calcium carbonate and help to control buoyancy. They lie on or
hover slightly above the bottom, using skirt-like fins for stability. This mantle is expanded and contracted to expel water from the mantle cavity through an organ called
the funnel. The mouth consists of a parrot-like beak, jaws, and a rasping tongue.
Cuttlefish use their two feeding tentacles to help catch a meal of small crustaceans
and fish.
Cuttlefish tend to be solitary animals, however in the spring and summer,
thousands of these creatures congregate for mating. Mating takes place when the
male places his spermatophore in a pouch under the female’s mouth. When the capsules burst they release sperm into the female’s mantle and fertilize the eggs. The
eggs develop a leathery egg case and are then laid individually in caves or on rocky
reefs. Four months later, the young emerge. Cuttlefish typically live about two years.
Cuttlefish use their vast color changing ability to help protect themselves from predators. But if changing color isn’t enough, the cuttlefish can also change its texture by
raising or lowering its skin helping it blend in to rocks or coral. If neither attempt at
camouflage works, the cuttlefish will jet away leaving a cloud of ink in the face of the
attacker.
The Pharaoh cuttlefish is much smaller than its cousin the giant cuttlefish,
averaging 12-16 inches in length. Its lifespan is less than one year. This species is
found from the Red Sea to Japan and Australia and support a large fishery. This
species feeds on fish, shrimp and crabs. The cuttlefish came to the Aquarium from the
National Resource Center for Cephalopods in Galveston, Texas.
Emperor Nautilus
Nautilus pompilis
The nautilus belongs to the same class of
animals as octopi, mollusks and squid, the Cephalopods. The nautilus has an external shell unlike that
of some of its relatives. Their spiral shell is divided
internally into gas-filled chambers that provides for
their buoyancy. The shell also offers them protection. The nautilus is slow moving and considered to
be quite primitive with fossil records dating back 200
million years. This beautiful creature is widely
collected for its attractive shell. The desire for them
has put pressure on their populations and caused some
areas, such as Indonesia, to offer them protection by law. The
nautilus lives much longer than some of its relatives, taking 5-10 years to reach maturity. Their reproductive rate is slow and they generally lay only a few dozen eggs a
year. Very little is known about their hatching rate. The nautilus came to the
Aquarium from the National Resource Center for Cephalopods in Galveston, Texas.
Jellyfish
Of all the animals, jellyfish are perhaps the simplest,
yet most mysterious. Despite bodies that are 97 percent
water, a very limited nervous system, and the lack of eyes,
ears, or a brain, these phantoms of the deep travel widely,
populating the world’s oceans. Although many people fear jellies for their sometimes
dangerous stinging abilities, when they discover the secret life of these ocean-going
phantoms, their fear fades as their curiosity and sense of wonder grows.
Jellies are invertebrates with bodies that consist of a jelly-like substance, called
mesoglea. Many people are familiar with jellyfish, but the lesser known jellies include
organisms called comb jellies. The jellyfish and the comb jellies actually belong to two
separate phyla, the Cnidaria (pronounced ny-DARE-ee-a) and the Ctenophora (teenuh-FOR-a). The Cnidarians include other well-known animals such as the corals, sea
anemones, and hydras. Members of the Cnidarian phylum all have one thing in common: the ability to sting. The majority of Ctenophores cannot sting and use cilia to
swim.
The origin of the word Cnidaria comes from the Greek word ‘cnide’ meaning
nettle. The Cnidarians have a flower-like appearance, for example a hydra or sea
anemone. Members of the Cnidarian phylum are all carnivores, feeding on anything
from zooplankton and fish to other jellyfish. There are approximately 10,000 living
species which are almost entirely marine dwelling. They can be free-swimming or
sessile, solitary or colonial. Cnidarians have an extremely simple body structure with
only the inner and outer tissue layers developed and the middle layer, or mesoglea,
consisting of a simple protein jelly matrix. Tentacles with specialized stinging cells
surround the mouth. Its digestive system consists of an extremely simple gastrovascular cavity, which has only one opening, the mouth, for food to enter and wastes to exit.
The well-known stinging ability of the Cnidarians comes from a specialized cell
called a cnidocyte (NY-doe-site). Cnidocytes contain a stinging capsule or nematocyst
(new-MAT-a-cist). The nematocyst, when not being used, is coiled up like a spring
inside the cnidocyte. One end
of the coil is attached to the cell
while the other end resembles
a harpoon, with various barbs,
hooks, or spines. The
Nematocyst
Cnidocyte
cnidocysts are usually located
along the tentacles that surround the mouth of the
cnidarian. When an unsuspecting animal passing by brushes against these tentacles,
the cnidocytes release the nematocysts, which spring out and hook into the passerby.
In milliseconds, the nematocysts fires, making this cellular process one of the fastest in
nature. Some jellyfish have nematocysts that inject poison; others simply entangle the
prey. Once an animal is either paralyzed or entangled, the tentacles slowly draw the
prey towards the mouth. Most Jellyfish do not actively hunt other animals; instead,
food acquisition is a random process. Any animal that touches the tentacles is stung.
However, even a jellyfish that has washed ashore should not be handled, since
the nematocysts may still fire. The stings of some jellyfish may be quite painful, causing reactions ranging from mild rashes to death. The most dangerous jellyfish is the
Australian box jelly,Chironex fleckeri. The toxin of this species is more potent than
cobra venom, which can kill a person in less than five minutes.
Despite the stinging cells, some animals do eat jellyfish. For example, the ocean
sunfish, Mola mola, and several species of sea turtles, such as the leatherback,
Dermochelys coriacea, feed primarily on jellyfish. Seabirds, crustaceans, and various
fish also include jellyfish as a part of their diet. Certain species of jellyfish will even
prey upon other types of jellyfish, and some cultures consider jellyfish quite a delicacy.
Most jellyfish are harmless to human beings. In fact, these graceful creatures
can benefit people. DNA from some bioluminescent jellies is used to help detect cancer
cells and cancer-causing chemicals. Some jellyfish species are beneficial to other
animals, such as providing shelter in open water for tiny fish and crabs that travel
carefully under their jellyfish host’s bell. The East Coast sea nettle may actually help
the oyster population by eating the comb jelly. Comb jellies eat oyster larvae in large
numbers, thus potentially reducing the number of mature oysters available for harvest.
The fewer comb jellies there are in an area, the more oysters there will be. So although
most people do not like finding sea nettles where they want to swim, if the jellyfish are
eating comb jellies, the oysters appreciate them--and so do the people who eat oysters!
Jellies have a very complex life cycle which
includes four phases. First is the medusa phase.
When most people think of “jellies”, they picture
the medusa phase. This is a free swimming phase
that is responsible for the sexual reproduction of
the species. Each individual medusa is male or
female, and during spawning will release gaMedusa
metes, sperm or eggs, into the water. When a
Polyp
jellyfish egg is fertilized, it will
develop into the second phase, known as a planula.
The microscopic
planula will swim for about 48 hours, settle onto a hard surface, and develop into a
polyp. Polyps are the asexual phase of the life cycle and closely resemble a tiny
anemone. They can reproduce in two distinct ways, through budding and through
strobilation.
During budding, an offspring grows from a body part of a parent polyp. A single
polyp can give rise to an entire colony of polyps by budding. During strobilation, the
top portion of the polyp divides into segments. Each segment will eventually break
away from the polyp and become free-swimming. This free-swimming phase, known as
ephyra, will eat and grow and eventually undergo a metamorphosis into a medusa.
Not all jellies stick closely to this plan however. For example, small hydromedusas,
like the umbrella jelly, skip the ephyra phase altogether.
The jelly lifecycle alternates between sexual and asexual reproduction. This
strategy is known as “alternation of generations”.
.
Adult
Medusa
Planula
Ephyra
Polyp
Strobila
Despite limited sensory organs, jellyfish can smell, taste and remain balanced in
the water. Special sacs, or statocysts (STAT-o-cists), located on the bell rim help the
jellyfish maintain balance. When a jellyfish shifts too far to one side or the other, the
sacs stimulate nerve endings to contract muscles that re-orient the jellyfish in the
correct direction. This process is similar to the balance-maintaining sacs found in the
inner ear of humans. Some jellyfish also have rhopalia (roe-PAL-e-a), light sensing
organs, located around the rim of the bell. The rhopalia can also sense smells and
tastes through chemicals released in the water.
Medusa Anatomy
Bell
Epidermis with coronal muscles
Statocysts and
Rhopalia
Medusa Underside
Gonad
Oral Arms
Tentacles
Jellyfish mostly drift with the currents, but they can swim to move short distances or redirect themselves. By contracting muscles in their bell, water is forced out
and the jelly is propelled in the opposite direction. The muscles then relax and the bell
gently springs back into its “open” position. This pulsing motion closely resembles an
umbrella being closed and opened. At the cellular level, jellyfish muscles look almost
identical to human muscles, but their “muscles” are only one cell thick!
Jellies: Living Art
This gallery combines the glimmering world of animals and art. Six species of
jellies capture the imagination as they pulse inside displays next to striking studio
glass. The exhibit illustrates how the jellies and the arts share common characteristics
of color, pattern, movement, and rhythm. The works of Thomas Spake, Dale Chihuly,
Cork Marcheschi and Stephen Powell are exhibited throughout this first floor gallery.
In one section of the gallery, jelly displays are paired with mirrors to create a
visual illusion which surrounds guests with endless moon jellies.
This is a collaborative exhibit with the Hunter Museum of American Art.
West Coast (Brown) Sea Nettle (Jellies: Living Art)
Chrysaora fuscescens
This long, flowing species inhabits the Pacific waters off
the western coast of the United States. Often abundant
in large numbers, this jellyfish grows to a diameter of 2
feet. The oral arms act as a digestive organ for prey too
large to fit in the jelly’s mouth. Its sting is mildly toxic
and has been compared to that of a bee. The nematocysts are located on the bell, as well as the tentacles, and
appear as fine bumps. Like other jellies, these play a
role in the planktonic food web, feeding on other jellies, plankton and larval fish. This
jellyfish is often found with larval and juvenile Cancer crabs hitchhiking inside the
bell.
.Umbrella Jellyfish ( in Jellies: Living Art)
Eutonia indicans
This jellyfish truly lives up to its name, as not only does it have an “umbrella” formed
by the bell, it appears to have the handle of the umbrella which is formed by the mouth
stalk or manubrium. This jelly species is completely transparent and inhabits the cool
waters of the Pacific coast. The umbrella jellyfish is a Hydrozoan, related to the elegant jellyfish. In the wild these creatures feed on zooplankton. They are a small jelly,
rarely exceeding 2.5 cm. The umbrella jellyfish can be found during its polyp stage
living in eelgrass beds. In the Aquarium, these jellies will be fed a diet of brine
shrimp.
Moon Jellyfish (located in Jellies: Living Art and Boneless Beauties)
Aurelia aurita
The moon jelly is probably the most widely studied of the jelly species. They are often
found in huge masses or “smacks” drifting in the waters from the Arctic to Florida
and Mexico and from Alaska to southern California. Its bell width has been recorded
between 5-40 cm and its toxin is mild, producing a rash-like effect. Like most other
jelly species, it feeds on a diet of zooplankton, mollusk larvae, crustaceans, diatoms,
rotifers and protozoans. Along with its four oral arms, the moon has hundreds of short
tentacles along the margin of its bell. The four distinct horseshoe-shaped areas seen
from the top of the bell are the gonads and stomachs. In the Aquarium, these jellies
will be fed brine shrimp and chopped seafood.
Blubber Jellyfish(in Jellies: Living Art)
Catostylus mosaicus
Size: to 12 inches in diameter
Range: coastal waters of north and eastern Australia
Wild Diet: small zooplankton
Blubber jellyfish can range in color from tan to bright blue to deep purple. Their coloration is believed to be a form of sunscreen, and intensifies when they are exposed to
sunlight
When dried and preserved properly, this species is considered a delicacy in many Asian
countries. With its numbers increasing in Australian waters, many fishermen have
turned to harvesting the blubber jellyfish to sell to foreign markets.
Upside-down Jellyfish(in Jellies: Living Art)
Cassiopeia sp
Size: to 12 inches in diameter
Range: shallow, coastal, tropical waters, Indo-Pacific and Caribbean Oceans, Gulf of
Mexico, and Hawaii
Wild Diet: some small plankton, but primarily photosynthetic deriving much of it food
from symbiotic algae (zooxanthallae).
Unlike most other jellies, this species rests upside-down on the sea floor and rarely
swims.
Upside down jellies are commonly found basking in mangrove swamps and sea grass
beds. These habitats are two of the most threatened habitats on Earth. They are
easily damaged by human activities and coastal development.
Sea Walnut(in Jellies: Living Art)
Mnemiopsis leidyi
Size: to 5 inches long
Range: native to western Atlantic coastal waters, including
the Gulf of Mexico, introduced elsewhere.
Wild diet: small planktonic crustaceans, fish eggs and larvae,
and occasionally other comb jellies.
Sea Walnuts are not true jellyfish, instead they belong
to a group of animals known as “comb jellies”. Comb jellies have no stinging cells, but
instead use sticky mucous to catch their prey. These animals get their name from rows
of paddle-like hairs, called combs. Like tiny prisms, these hairs refract visible light
into a pulsing rainbow. In the 1980’s, comb jellies were accidentally introduced into the
Black Sea--most likely via ship ballast water. Without a natural predator, the comb
jellies quickly took over their new home and devastated local anchovy fisheries. Despite the introduction of a natural predator, Beroe, that has helped control the invading
comb jellies, the Black Sea fisheries have yet to recover.
Ctenophores
The Ctenophores, or comb jellies, are often mistaken for jellyfish due to their
clear, jelly-like bodies. In fact, at one time the comb jellies were included in the same
phylum as Cnidarians. However, upon closer inspection, it is evident that there are
distinct differences. One of the major differences is the lack of nematocysts in the
Ctenophores. Instead, most use sticky mucous to capture their prey. There are approximately 100 known species of Ctenophores and all are restricted to marine environments.
Lacking the bell that is present in most jellyfish, comb jellies rely on eight rows
of cilia for locomotion. The name ctenophore comes from the Greek word for comb,
cteno, referring to the rows or combs of cilia in the animal. The cilia wave in unison,
enabling the comb jellies to move. Ctenophores are the largest animals that use cilia
for locomotion. The size of comb jellies can range from one to ten centimeters; however,
there are some species that have ribbon-like bodies reaching more than one meter in
length. Comb jellies’ bodies are translucent and very fragile. Their diet is similar to
that of the jellyfish. Ctenophores consume zooplankton, small fish, jellyfish, and other
comb jellies. Some comb jellies are more selective about their diet, only hunting and
eating a certain type of organism.
Little is known about Ctenophore reproduction. However, we do know that they
are simultaneous hermaphrodites, meaning both male and female reproductive tissue
are found in one animal.
Possible Future Exhibit Species:
Purple-Striped Jellyfish
Chrysaora colorata
Amakusa Jellyfish
Sanderia malayensis
Lion’s Mane Jellyfish
Cyanea capillata
Crystal Jellyfish
Aequorea victoria
Black Sea Nettle
Chrysaora achlyos
Lagoon Jellyfish
Mastigias papua
New Species in Boneless Beauties:
Japanese Sea Nettle
Chrysaora melanaster
Size: to 25 inches in diameter
Range: Pacific ocean, Japan and North to the Bering Sea
Wild Diet: feeds on small crustaceans, pelagic tunicates and mollusks, fish eggs and
larvae, and other jellies.
The Japanese sea nettle has a light-colored bell with a dark orange sunburst pattern
radiating to its edges. Tentacles can stream behind the Japanese sea nettle for 9-20
feet. Their nematocysts are powerful, capable of causing serious skin irritation and
burning sensations.
Japanese sea nettle populations appear to be increasing in the Bering Sea. Scientists
studying the phenomenon are concerned because this species may feed on the same
plankton species targeted by herring, sardines, anchovies, juvenile salmon and other
commercially important species of fishes.
Jellyfish Fun Facts
• There are more than 10,000 living species of jellyfish in the world, most of which are
marine. One species of jellyfish, Craspedacusta sowerbyii, is known to inhabit fresh
water lakes and ponds.
• Open ocean living jellyfish have mostly eliminated the sessile polyp lifestage.
• Ctenophores are the largest animals that use cilia to move. Many resemble ribbons
and can acheive lengths over 1 meter long.
• A group of jellyfish is called a ‘smack’.
• The effectiveness of cnidarians in snaring prey was amply demonstrated in a fjord in
the western Baltic Sea, where a heavy bloom of jellyfish reduced the larval herring
population to less than half its former density in just a few weeks. One jellyfish
only 4.2 cm in diameter contained 68 larvae!
• The name “medusa” was suggested by a somewhat similar resemblance to the Gorgon
Medusa, a mythogical woman with snake-like tresses that turned to stone anyone
that gazed upon her.
• The jelly-filled umbrella (or bell) of some species of jellyfish are eaten in eastern Asia.
The jellies are preserved in rock salt or alum or stored in leaves of Kashiwa oak
trees. The medusa is softened in water, washed, and cut into small pieces, sea
soned, and eaten. It is said to taste like salted gherkin pickles.
• In May 1991, some 2,500 moon jellies blasted into space aboard the space shuttle
Columbia. Scientists studied how their balance organs developed in a weightless
environment.
• When food is scarce, adaptable jellies don’t starve. Some can “de-grow” - actually
shrink in size so they don’t have to eat as much to survive. When food is plentiful
again, they re-grow.
• When threatened by a predator, a jellyfish may lose its
tentacles, but it will grow replacements.
• Jellyfish stingers still function after six months of drying as long
as they are placed in water.