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They’re weird; they’re wonderful; they’re “Boneless Beauties”

Special exhibition features octopi, jellyfish, and other invertebrates

CHATTANOOGA, 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.

Located 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.

“Although 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.”

While visitors may be familiar with some of the animals found in the “Boneless Beauties” gallery, others are quite difficult to spot in the wild.

“If 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 getting stung.”

In addition to the giant Pacific octopus and the jellies, featured animals include the giant Japanese spider crab, cuttlefish and chambered nautilus.

“Octopi 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.”

The “Boneless Beauties” gallery offers visitors a chance to connect with these rarely seen invertebrates.

“We 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.

An octopus 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 nautilus.

The 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.

Octopi 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.

Like 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.

When 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.

Octopi 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.

Octopi 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.

The 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, Sepia sp.
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.

Like 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.

With 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).

Although 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.

Emperor 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.

The 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 energy.

Nearly 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.

The 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 over collecting.

This 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.

Jellyfish 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.

Despite 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.

Jellyfish 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.

Jellyfish 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.

The 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.

The Tennessee Aquarium inspires wonder and appreciation for the natural world. Admission is $17.95 per adult and $9.50 per child, ages 3-12. Each ticket purchased helps support Aquarium conservation programs. The IMAX® 3D Theater is next door to the Aquarium. Ticket prices are $7.95 per adult and $5.50 per child. Aquarium/IMAX combo tickets are $21.95 for adults and $12.50 for children. Advance tickets may be purchased online at or by phone at 1-800-262-0695. The Aquarium, located on the banks of the Tennessee River in Chattanooga, is a non-profit organization. Open every day except Thanksgiving and Christmas, the Aquarium and IMAX are accessible to people with disabilities. Members enjoy unlimited visits and other benefits. Call 267-FISH to join.

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