Originally aired during the week of February 18, 2002
Every good coach knows you gotta play good "D" to win games. That's "D" for defense! Of course, whether athletes win or lose, they always have the luxury of coming back to play another day. In nature, the games animals play are matters of "life or death." That's because animals are all part of the food chain. Sometimes the animal is the hunter, sometimes it is the prey. Survival is the name of this game, and to win the animal has to develop defenses against predators. Nature has equipped creatures with a variety of weapons to provide protection including the usual assortment of claws, teeth, fangs, venom, and paralyzing poisons. But other animals use less obvious ways to play "D." Our friend the skunk turns the predator's sense of smell against it by issuing a stream of oily, foul smelling musk. This week we'll learn more about some other defenses animals employ.
Maybe you remember the scene in the recent Star Wars Movie
The Phantom Menace - the part where the heroes are cruising along in a little underwater ship. A monstrous fish suddenly swims behind them, opening its jaws wide. The movie is about to end. But of course, an even more monstrous fish appears, swallowing the smaller fish in the nick of time! "There's always a bigger fish," says the Jedi knowingly. He was commenting on a basic truth, which even "the force" cannot alter - that is, we are all part of the food chain. So animals have developed a wide variety of strategies to defend themselves. The skunk can spray its oily yellow fluid from two glands about the size of a grape. The animal is not trigger-happy - it produces only about a third of an ounce of musk per week, so it saves up its ammunition for when it really needs it.
It's a dog eat dog world out there. In other words, eat or be eaten. So animals have developed some remarkable adaptations to defend themselves from predators. The porcupine doesn't rely on speed or balletic grace to elude attackers. It doesn't have to. It has about 30,000 sharp quills that stand at attention when the animal feels threatened. If a predator should climb up a tree to attack a porcupine, the porky will back down the trunk lashing its tail at the aggressor. The quills are hollow and taper to a point that is covered by tiny barbs. When embedded under the skin, the barbs swell up, pushing the quill further in. It can be a painful encounter for the predator. But some hunters have learned to penetrate the defenses of their prey. The fisher uses its sharp claws and teeth - and extraordinary quickness - to bypass the quills and attack the porky's soft underbelly.
Discretion is the better part of valor, the old saying goes. The skunk will only resort to spraying attackers when it has exhausted other options, including growling, hissing, or simply waddling away from danger. Like the restrained lawman of the mythical western town, he's not looking for a fight--he only shoots when it has to. The motto for the American opossum might be: if you can't beat 'em, bore 'em. Actually, when its cornered, the opossum will growl and snap at aggressors with its sharp teeth. Only as a last resort, it might fall limp, either paralyzed with fear or playing dead. The opossum lies quite still, with gaping mouth and glassy eyes, sometimes emitting a fluid from its anal glands suggesting the smell of rotting flesh. Often enough, the hunter lopes away in search of more lively and challenging prey.
Animals use all sorts of tactics to avoid being eaten. Some species of lizards even sacrifice body parts to get away from predators! The vertebrae in the tails of these animals contain weak points or "fracture planes." When the lizard is caught from behind, its tail will detach from its body. The tail might even thrash about for a time, confusing the predator. Can't you just hear the lizards saying: "Hey you want a piece of me? Well, come and get it! You can have my tail, but you won't get me!" The horned toad has also come up with a unique defense. It can be briefly described as: the "bleed all over your opponent" strategy. When backed into a corner, this toad can raise its blood pressure, breaking open the thin-walled sinuses it's eye sockets and releasing streams of toad blood into the predator's face. Reflex bleeding. Now that's tough defense!
