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The secret lives of invertebrates (Photos)

Wednesday - 6/18/2014, 6:12am  ET

Cuttlefish can be found in the Atlantic Ocean and Mediterranean Sea. Their unique biological makeup allows them to voluntarily change color and texture. They are known as the "chameleon of the sea." (WTOP/Alicia Lozano)


The exhibit, arguably one of the zoo's most underrated gems, is home to more than 100 different species, a spokeswoman says. They include everything from creepy, crawly spiders to adorable cuttlefish. Lesser-seen creatures such as corals, anemones and water scorpions also are part of the unusual mix.

These animals have been on display since 1987, when the zoo first opened the exhibit in an effort to "educate visitors about invertebrates as nature's unsung heroes." If you like lobster and crabs, listen up.

Invertebrates comprise 99 percent of all known living species on Earth. They do not have backbones and are cold-blooded, but that does not make them mean or evil in any way. In fact, some of the world's prettiest creatures, such as butterflies, are invertebrates. The classification include insects, spiders, crustaceans, worms, mollusks and coral.

Here is a breakdown of what makes each type of invertebrate tick:

Insects: Some fly, some crawl; some bite and some don't. Insects are defined by their three-part bodies, three pairs of jointed legs and one pair of antennae. More than one million organisms on Earth are insects, and they represent more than 80 percent of animal life, according to Smithsonian Encyclopedia.

There are 91,000 types of insects in the United States alone. Some familiar insect classification include beetles flies, ants, bees and wasps; and moths and butterflies.

Spiders: Members of this arachnid family breathe air, have eight legs and sport fangs that can inject (potentially dangerous) venom. Unlike insects, spiders do not have antennae. Their webs vary in size and strength. The earliest spider ancestors date back more than 300 million years.

The world's most poisonous spider, the Brazilian wandering spider, grows to be about the size of a small dinner plate. A bite can cause an "unwanted erection in men, sometimes lasting for four hours," the Daily Mirror reports.

Crustaceans Both delicious and weird-looking, crustaceans include familiar animals such as crabs, lobsters, crayfish, shrimp, krill and barnacles. They have exoskeletons that are composed of three different sections: head, thorax and abdomen. Most crustaceans are aquatic, but a few family members -- such as hermit crabs -- have adapted to live outside water.

Worms: They have no exoskeleton or legs and are identified by their soft, tube-like bodies. While mostly benign, except for the parasitic kind, worms generally keep to themselves. But Mongolian legend speaks of a "giant sand worm that spits venom and emits electricity from its body." Is it real? Find out below:

MollusksThere are more than 50,000 known species of this group, according to the Oceanic Research Group. Like crustaceans, their bodies can be split into three parts: the head, body and "foot." The head is home to the brain, the body to internal organs and the lower "footlike" region is used for transportation. Many mollusks also have a kind of tongue that is rough like sandpaper and used to rasp away food. All mollusks are aquatic.

Coral: This species is among the oldest on the planet, forming more than half a billion years ago, according to the Oceanic Research Group. They are colorful, diverse and teeming with life. Coral share some similarities with their distant cousins, anemones and jellyfish. They can sting and capture prey.

Coral reefs act as a kind of community center for thousands of underwater species, but coral themselves are individual organisms that eat, breathe and grow on their own. A reef is made from thousands of coral polyps that combined to create one hard structure.

Learn more about reefs in the video below:

Click through the gallery to learn more about invertebrates and other strange creatures at the National Zoo.


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