Páginas: 10 (2377 palabras) Publicado: 14 de abril de 2010

Sea Slugs Babosas marinas
You are what you eat. You may have heard this idea before. Food gives you the energy you need to move and grow. Well, little sea creatures called nudibranchs take this to a whole new level. These colorful, squishy blobs are masters of their meals. The food they eat holds the secrets to their survival.
Out ofTheir Shell
Before we get to all the food facts, here are some basics. Nudibranchs are a type of sea slug. They belong to the group of animals known as mollusks, along with clams, oysters, and snails. But unlike those well-armored creatures, these sea slugs have no shell for protection. They are just blobs of muscle, skin, and organs. Most are about the size of your finger, though some can grow aslong as a computer keyboard.
Animals that live in the ocean usually breathe with gills that are tucked neatly inside their bodies. Not nudibranchs. Most have gills that stick out of their backs in colorful, feathery tufts. When in danger, they can quickly pull the important gills inside their bodies.
Slugs On the Move
Nudibranchs crawl through the world's oceans, from frigid seas to warmtropical waters. Some species even live near the boiling vents of underwater volcanoes.
Nudibranchs are rarely in a hurry. To inch along over coral and rocks, they use a flat muscle on their underside, called a sticky foot. The foot ripples from back to front, slowly pulling the slug forward. True to its name, the foot leaves behind a trail of sticky slime.
Some nudibranchs are able to leave the oceanfloor and swim short distances. One is the Spanish dancer. It moves by tightening and releasing its muscles. As it swims, it looks like the swishing red skirt of a flamenco dancer.
Living Color
Nudibranchs are as colorful as a candy store. One type sports pink polka dots and flashy red gills. Another is royal blue with yellow and black stripes that line its body. Some nudibranchs are round andchubby. Others are long and sleek. If you imagine a shape and color, there is probably a nudibranch to match.
Now that you have the basics, are you ready for the first important food fact? Nudibranchs get their amazing colors from the food they eat. For example, when one eats a sponge, it absorbs the sponge's color pigments. Eating an orange sponge gives a slug tinges of orange. Eating a redsponge can turn a slug red—and so on.
For these shell-less little creatures, matching the colors of their food is about more than just looking good. It's about defense. A hungry sea turtle may have a hard time spotting a red slug eating a red sponge.
Nudibranchs can't see their own rainbow colors. That's because their tiny eyes can only see white, black, and shades of gray. They also lack a nose,ears, and tongue. Instead, they use two tentacles, called rhinophores to smell, feel, and taste things around them.
Nudibranchs eat things like coral, sponges, and anemones. Also on the menu are other sea slugs! That's right—nudibranchs will sometimes eat other nudibranchs. Maybe that's a food fact better left untold.
Snack Attack!
Without a shell, how do these slow-moving sea slugs stand a chanceagainst predators? It's time for the second food fact: Nudibranchs can turn their food into a weapon.
Stinging sea anemones are a popular nudibranch meal. They eat the anemone—stingers and all. They don't digest the stingers, though. The stingers settle in the nudibranchs' cerata. These are finger-like parts some slugs have on their backs for breathing, digestion, and in this case, defense.Should something try to chew on the slugs, they can use the stingers as weapons. Ouch!
Stingers aren't the only weapons these sea slugs steal from their meals. Some nudibranchs dine on poisonous sponges. The toxins don't hurt nudibranchs—they help. The sea slugs store the poisons to use later. When they are threatened, the nudibranchs release the toxins into the water around them. The cloud of...
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