They’re weird; they’re wonderful; they’re
Special exhibition features octopi, jellyfish,
and other invertebrates
Tenn. (Feb. 21, 2005) – Like creatures from a science-fiction
film, they have bulbous heads surrounded by tentacles; others
have armored bodies with impossibly long legs. They have skins
that can change color, or boneless bodies encased in a protective
shell. But they aren’t invaders from another planet; they’re
residents of Earth and make up 95 percent of all animal life.
These “Boneless Beauties” are invertebrates and
the stars of one the new galleries in the Tennessee Aquarium’s
new Ocean Journey.
on Level 2 of the new Ocean Journey building, the “Boneless
Beauties” gallery gives visitors a close-up look at some
of the ocean’s most unusual invertebrates. From the delicate
jellyfish to the heavily armored giant spider crabs, this gallery
explores the mysterious world of rarely seen invertebrates.
these animals share the common trait of having no internal skeletons,
they exhibit a great deal of variety in appearance and behavior,”
said Thom Demas, Aquarium curator of fishes. “We have
the jellyfish – relatively simple animals with a limited
central nervous system – and then we have the giant Pacific
octopus, which has a complex brain that can even solve puzzles.”
visitors may be familiar with some of the animals found in the
“Boneless Beauties” gallery, others are quite difficult
to spot in the wild.
you’ve been to the beach, then you’ve probably seen
jellyfish washed up on the shore,” Demas said. “But
this gallery allows you to experience jellyfish in a way that
you just can’t in the wild. Well, at least not without
to the giant Pacific octopus and the jellies, featured animals
include the giant Japanese spider crab, cuttlefish and chambered
are very shy and are experts at hiding – even scuba divers
are lucky to get a glimpse of one,” he said. “And
giant Japanese spider crabs live in deep, cold parts of the
ocean where divers rarely go.”
“Boneless Beauties” gallery offers visitors a chance
to connect with these rarely seen invertebrates.
know our visitors will leave with a new appreciation for these
unusual animals,” Demas said.
Giant Pacific Octopus, Enteroctopus doflenini
From the early days of man’s history, storytellers have
spun tales of frightening sea monsters with mottled skin and
long tentacles lined with suction cups. One look at the giant
Pacific octopus and it’s easy to see why this animal continues
to capture the imagination.
is an invertebrate with a soft, bulb-like body, eight tentacles
with two rows of suction cups each, a well-developed brain and
two complex eyes. They are relatives of the squid and the chambered
body of an octopus, called the mantle, houses the stomach, the
hearts (yes, hearts!) and other body organs. An octopus has
three hearts that pump blue blood. Two of the hearts pump blood
through the gills. The third heart pumps blood throughout the
body. Due to the extreme sensitivity of the suction cups on
its tentacles, an octopus has a keen sense of touch. The suction
cups also have receptors that function much like taste buds.
An octopus can sense the presence of fish, or shellfish oil
in the water or on objects placed in its exhibit. Octopi have
visual acuity comparable to that of humans.
are intelligent and highly adaptable animals. They can be found
in almost every type of ocean environment, from the shallow
waters near coasts to the deep sea. They come in a variety of
shapes and sizes. The giant Pacific octopus is the largest of
the octopus species. Giant Pacific octopi may reach weights
of several hundred pounds and can have tentacles that span more
than 30 feet. This species is found in the Pacific Ocean from
southern California along the coast of Central and South America,
to the Aleutian Islands and Japan.
many octopi, the giant Pacific octopus has the ability to drastically
change its color to blend into its environment or to attract
a mate. Special pigment cells in the skin, called chromatophores,
can be activated in an attempt to blend in with the surroundings.
Chromatophore cells consist of three “bags” containing
different colors that are adjusted individually until the octopus
matches its surroundings. This ability to change colors helps
the octopus hide or hunt, but coloration can also reflect mood.
threatened, an octopus often will try to escape by releasing
a cloud of purple-black ink to confuse the enemy. Its body will
change color, release a cloud of ink and swim away. In addition
to providing a cover for the octopus to escape, the ink is also
toxic – even to the octopus that released it.
are considered the most intelligent of all the invertebrates.
Although they are shy, they are also curious and explore their
environments. In the wild, they are cunning and persistent hunters,
pursuing small crabs, shrimp and fish in cracks and crevasses
in the ocean floor, coaxing them out with their long tentacles.
Octopi will also use their arms to pull apart the shells of
mollusks. At the Aquarium, the octopi are given puzzles to solve,
like a bell jar with a piece of soft-shell crab inside. The
octopi quickly learn to unscrew the tops of the jars to get
to the food inside.
eat small crabs and scallops, snails, fish and even other octopi.
In addition to using its tentacles to pull apart shells, it
also secretes a substance that softens the shell to allow the
octopus entry. Then, the octopus will inject a toxin through
its parrot-like beak that helps to dissolve the prey, making
it easier to digest.
octopus is also an excellent escape artist, able to squeeze
its boneless body through an amazingly tiny space or use its
tentacles to climb acrylic panels. Aquarium staff members use
Astro-turf to surround the inside ledges of the octopus exhibit.
The suction cups of an octopus cannot adhere to this material,
thus preventing it from climbing out.
Cuttlefish seem to be assembled from a variety of random body
parts. They have sucker-lined appendages that grow from their
heads – eight arms and two feeding tentacles that are
used to catch small crustaceans and fish. Cuttlefish have large
eyes and excellent vision. The main body, or mantle, of the
cuttlefish can expand and contract to expel water through an
organ called a funnel. This allows the cuttlefish to move through
the water. Skirt-like fins surround the mantle and help the
animal remain stable in the water. An internal shell, called
a cuttlebone, gives shape to the mantle and helps the cuttlefish
control its buoyancy. The cuttlebone is not really a bone, but
is made of calcium carbonate. The cuttlefish’s mouth consists
of a bird-like beak, strong jaws and a rasping tongue.
the octopus, the cuttlefish is a master of disguise and a quick
color-change artist. These “chameleons of the sea,”
use chromatophores to change color. A cuttlefish also can change
the texture of its skin, raising or lowering it to help the
animal blend in with rocks or coral. This natural camouflage
helps the cuttlefish hide from predators. If hiding is not successful,
the cuttlefish has one last defense: it can jet away, leaving
behind a cloud of toxic ink in the face of its attacker.
Giant Spider Crab, Macrocheira kaempferi
Deep in the dark waters off the coast of Japan live creatures
that resemble giant, armored spiders. They make their homes
in the vents and holes found in the ocean floor at depths of
100 to 165 feet – a cold and desolate part of the ocean.
a body that can reach 15 inches in diameter and a leg span approaching
lengths of 15 feet, the giant spider crab is the world’s
largest arthropod (invertebrate animals with segmented bodies
and jointed appendages). The word arthropod means “jointed
legs” and giant spider crabs have plenty of those –
10 legs in all. Two of these legs are modified large claws called
chelipeds. The male crabs have larger claws than the females.
Like other completely aquatic animals, spider crabs breathe
using gills. Spider crab gills are located under their carapaces
(the shell that covers the back of the crab).
this is the largest of all crabs, it still must protect itself
from predators. Their armored exoskeletons help protect them
from larger predators such as octopi, but giant spider crabs
also use camouflage. The crab’s bumpy carapace blends
into the rocky ocean floor. To further the illusion, a spider
crab will adorn its shell with sponges and other animals.
Nautilus, Nautilus pompilis
Most people are familiar with the beautifully marked, attractively
curved shell of the nautilus, but many know very little about
the animals that live inside.
nautilus is related to octopi, squid and mollusks. Like those
animals, the nautilus has a soft body with no internal skeleton.
A hard external shell protects the soft body of the nautilus.
The inside of this graceful, spiral shell is separated into
gas-filled chambers that allow the animal to float, conserving
100 tentacles form a ring around the central mouth of the nautilus.
These tentacles lack the suction cups found on octopi. Instead,
the nautilus grips its prey with numerous ridges along the length
of the tentacle. Like its octopi relatives, the nautilus swims
by jet propulsion, squirting jets of water through a tube-like
funnel. It can retract into the shell, protecting itself with
a thick leathery trapdoor called a hood. The nautilus cannot
live if separated from its shell.
nautilus lives much longer than some of its relatives and may
take between 5 to 10 years to reach maturity. Their reproductive
rate is slow and individual females lay only a few dozen eggs
each year. This makes the nautilus particularly sensitive to
animal is widely collected for its attractive shell. The demand
for them has become so great that some areas, like Indonesia,
now protect them by law.
Moon Jellyfish, Aurelia aurita
West Coast Sea Nettle, Chrysaora fuscescens
Jellyfish are simple, yet fascinating creatures. Their bodies
are 97 percent water, with a very limited nervous system, no
eyes, no ears and no brain. Despite this simplicity, jellyfish
are found throughout the world and travel widely.
and their relatives, the comb jellyfish, are invertebrates with
bodies made up of a jelly-like substance called mesoglea. Jellyfish
and comb jellies are actually classified into separate groups,
with the biggest difference between them being that jellyfish
can sting while comb jellies cannot.
limited sensory organs, jellyfish can smell, taste and remain
balanced in the water. Special sacs, called statocysts, located
in the bell of the jellyfish help it maintain its balance in
the water. The statocysts are similar to the balance-maintaining
sacs found the in the inner ears of humans. Although they have
no eyes, jellyfish posses light-sensing organs that help distinguish
light from dark. These sensors can also sense smells and tastes.
swim using a type of jet propulsion. Muscles on the underside
of the jellyfish push water out of the hollow bell. As the water
is forced out, the jellyfish moves in the opposite direction.
In addition to this jet propulsion, jellyfish also are carried
by waves, currents and wind.
tentacles are studded with stinging cells that behave like tiny
harpoons armed with toxic chemicals. This stinging ability makes
the jelly an efficient predator and protects it against animals
that want to eat its soft body. Jellies don’t sting people
on purpose. It’s just that when the tentacles brush against
something, thousands of the cells explode, launching barbed
stingers into the victim.
graceful, phantom-like animals are ocean vagabonds, drifting
ceaselessly with the currents and tides. Many of them are almost
transparent – a convenient camouflage in their open habitats,
where there are no places to hide from predators. As they are
carried with the current, they are both predator and prey, catching
small animals, fish eggs, and other jellyfish in a net of tentacles.