BEST BLOOD-AND-FANGS AWARD VAMPIRE BAT
Vampire gear may be standard Halloween fare, but for true fright-night style, check out the audacious vampire bat. Each night, the nocturnal (night active) creature flaps its 20 centimeter (8 inch)-wide wings, carrying its tiny 8 cm (3 in.)-long body over the Central and South American countryside. Its only mission: to hunt for blood, its sole food source.
The bat hones in on large birds, pigs, or juicy cows ... and, very rarely, humans. Once it targets prey, heat sensors on the bat's nose zero in on a spot with plenty of capillaries (small blood vessels) close to the skin. Like a barber trimming a neckline, the bat snips the fur with its teeth. Then needle-sharp fangs scrape the skin, and the bat laps up flowing blood.
Normally, an animal's blood cells would quickly clot to block the blood flow--like what happens if you scratch yourself. But enzymes (proteins that speed up chemical reactions) in the bat's saliva keep the blood gushing. Scientist Robert Medcalf of Australia's Monash University is now studying one bat enzyme, called DSPA, to see if it might someday help stroke victims by dissolving clots that block blood flow to the brain.
BEST GLADIATOR GETUP LONGHORNED BEETLE
If you've ever paraded as a warriorhero or a super-villain, you may have a favorite plastic weapon. For the fearsome looking Macrodontia cervicornis, a species of longhorned beetle, the weapon of choice is its super mandible, or giant claw-like jaw.
"I've seen males use the mandibles for fighting," says Pinedo-Vasquez. The beetles use their saw-edged feature to knock "horns" in an insect sword fight, or to lever each other off South American tree trunks. During mating season, the winning gladiator is more likely to snag a female. Luckily for the loser, an armor-tough exoskeleton (external skeleton) protects its up to 17 cm (7 in.)-long body. The mandible is so in demand, "some people put them on gold chains and sell them to tourists," the ecologist adds.
There are more than 20,000 species of longhorned beetle--named for their very-long antennae. Another fearsome family trait: Longhorned larvae (maggot-like young) are known as "borers" because they chew through trees as they feed. In the U.S., the invader (nonnative) Asian longhorned beetle has wreaked havoc on trees in New York, New Jersey, and Illinois. Currently, the only way to stop its spread is to chop down infested trees and set fire to the wood. Scientists are still searching for effective pesticides or predators.
BEST HIDE-AND-SEEK HORROR STARGAZER FISH
Dress as a pile of sand, and you may end up a Halloween style disaster. But for the stargazer fish, its "costume" is a superstar award-winner. For starters, the fish camouflages, or hides, by blending its 46 cm (18 in.)- long body into its environment--in this case, the sandy seabed of warm coastal waters. In seconds, the stargazer scoops away sand with pectoral fins (chest fins) and buries itself right up to its flat face--located on the top of its head. Two protruding eyeballs scan the sea above for unsuspecting small fish and crustaceans. Then--gotcha! It lunges for a sneak attack.
The stargazer is only one of many predatory fish species that scan upward to spot prey. But animal survival isn't just a game of hide-and-seek. When the stargazer feels threatened by a bigger fish, it gets charged up--literally. Organs behind each eye generate up to 50 volts of electricity, enough to deliver a shock to anything that comes too close. Scientists think stargazers and other electrogenic (electricity-producing) fish, such as catfish, may also use electricity to communicate with one another.
The electric organ develops from muscle when the fish is young, which has scientists fascinated: It's very unusual for one type of cell to change into another. "It's as if the muscles in your legs changed to become electricity-generating organs," says biologist Graciela Unguez of New Mexico State University. Now, scientists are studying stargazers to learn how it occurs. Such research may teach doctors how to restore cells in people with muscle-paralyzing illnesses such as Lou Gehrig's disease.
MOST GHOSTLY GHOUL HATCHET-FISH
Use a flashlight to help you see while trick-or-treating in the dark? For the hatchetfish, light acts like Harry Potter's invisibility cloak.
"Stargazing" predatory fish snare prey when they see dark shapes swimming against the light from above. But the ghostly hatchetfish produces its own body light to blend into the dim blue sunlight filtering down 400 to 1,250 m (1,300 to 4,100 ft.) to its deep ocean habitat (home).
The style-conscious hatchetfish adjusts its own tint and brightness to match the water. In fact, the hatchetfish are like swimming glow sticks: They undergo a chemical reaction that releases energy in the form of visible light. The process is called bioluminescence.
The chemical reaction takes place in organs called photophores near the hatchetfish's belly. Inside, specialized cells or photocytes, produce light. Color filters in the photophores absorb non-blue shades, allowing the fish to exactly mimic its surroundings. Naturally, the hatchetfish needs energy for its fashion light show. So its eyes are permanently turned upward to scan for food sources like small crustaceans and plankton (tiny marine plants or animals). And its ghastly basket-shaped mouth is ready to catch sinking scraps. However, food is scarce in the deep sea. The hatchetfish's energy-saving solution: a tiny pared-down body--up to 8 cm (3 in.)--with little muscle and supermodelthin bones.
MOST OUTRAGEOUS MAKEOVER FRILLED LIZARD
Don't let this usually shy, drab reptile (class of cold-blooded scaly-skinned animals that crawl or move on their belly) fool you. The frilled lizard carries folds of extra skin around its neck, skewered on spokes of cartilage, or tough but bendy connective tissue. Normally, the native of northern Australia and New Guinea wears the frill folded down in the same brownish color as the rest of its body. This helps the 90 cm (35 in,)- tall forest dweller camouflage itself from predators like larger lizards, snakes, or birds.
But try to corner the lizard: It cranks open its mouth, and its neck frill--connected to the tongue and jaw--unfurls like a bright red umbrella. For added drama, the diva lizard hisses while lunging at its attacker.
The scary act shoos away most predators, even dogs. But feral (wild) cats don't fall for it. English settlers introduced cats Down Under in the 19th century as pest control. Today, an astounding 12 million wild cats roam Australia, preying on native wildlife. Luckily, the drama queen has a Plan B: Run! It sprints from danger on its hind legs. Though nobody has clocked the outrageous dresser, scientists believe it could tie in a race with its close relative, Lophognathus longirostris, at 24 km (15 mi.) per hour. The lizard hightails it for the nearest tree, where it bullies smaller lizards, insects, and spiders.
Did You Know?
* The stargazer wears fringes around its mouth to keep sand out. To breathe, most fish suck in water through the mouth, but a stargazer pulls it in through the nostrils. The water flows down to the gills, where oxygen spreads out into its body.
* The frilled lizard's collar is not all for show. Scientists think it may also help keep the cold-blooded reptile from freezing or overheating. When the frill is spread wide, its many blood vessels can soak up sunrays to warm the blood or to give off heat when the lizard feels too hot.
* Vampire bats groom each other and share food--by vomiting into the hungry bat's mouth. Despite the appearance, their sharp teeth don't hurt their victims. Ecologist Miguel Pinedo-Vasquez has been bitten many times while asleep. "Usually on the toe or the ear," he says. "When you wake up you have a little itch and you see the teeth marks." The danger: Some bats could spread rabies or other diseases.
Language Arts/Art: Select one of the animals featured in "Creep Show." Do additional research. Then write a short story or create a comic strip about one day in the life of the animal from the creature's point of view.
You read about the adaptations that make some animals fit for survival. What are some features that contribute to the overall fitness of humans?
Check out these Web sites to learn more about the amazing creatures featured in the story.
Vampire Bat: bss.sfsu.edu/geog/bholzman/courses/fall99projects /vampire.htm
Asian Longhorned Beetle: www.aphis.usda.gov/Ipa/issues/alb/alb.html
Stargazer: www.flmnh.ufl.edu/fish/Gallery/Descript/ StarGazerSouth/StarGazerSouth.htm
Hatchetfish and marine bioluminescence: www.bioscience-explained.org/EN1.1/features.html
Frilled Lizard: www.drellenrudolph.com/featureanimals/ frilledlizard.html
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|Title Annotation:||Life Science: adaptations/defenses|
|Date:||Nov 3, 2003|
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