Borrowing Poison
Borrowing Poison
Some poisonous animals make their own poison. Others use poison made by other living things. Scientists have discovered that these animals are ableto eat poisonous meals and store the chemicals in their bodies for use in defense.
Monarch butterflies get their poison from milkweed plants, on which monarch caterpillars feed. Many kinds of milkweed make poison to defend themselves from plant-eating animals. The poison causes heart failure, and most animals avoid it. It does not, however, affect monarch caterpillars. As they grow, they stock up milkweed poison in their bodies. The poison remains after they turn into butterflies.
The foaming grasshoppers of Africa get their poison by eating milkweed, too. Other insects obtain poison from other plants. The garden tiger moth, for example, makes some of its poison but gets the rest from plants it eats as a caterpillar, such as poisonous foxgloves. Cinnabar moth caterpillars become poisonous by eating toxic ragwort plants. The caterpillar of the rattlebox moth also eats poisonous plants. The adult rattlebox moth, which has a warning coloration, is so distasteful that if it is caught in a web, the spider cuts it free.
Some insects get their poison by eating other poisonous insects. One kind of fire-colored beetleeats blister beetles and stores the defensive chemicals in its body. Some of the chemicals leak into a groove on its head. A femalefire-colored beetlewill accept a maleas a mate only if he has a good supply of these chemicals. He will give her some of the chemical, which she will then pass on to her eggs. The chemical repels ants and other insects that might eat the eggs.
Cochineal insects, which feed on cactuses in American deserts, also make a defensive chemical that is stolen by other insects. This chemical, a red acid, repels ants and most other insects. But some insects are not bothered by it. One kind of moth caterpillar eats cochineal insects, and then when a predator bothers it, the moth caterpillar throws up the acid along with its stomach contents. Ants that get slimed with this substance give up their attack. The larva of a species of ladybug also eats cochineal insects. Its body uses the bug’s acid as part of the beetle’s reflex-bleeding defense. The larvae of a fly species that eat cochineal insects excrete the acid to repel predators.
Other animals can eat poisonous bugs without being harmed, and then use the poison themselves. Poison dart frogs do not actually make their own poison; they get it from the insects they eat. Their most likely source is a beetle. Poisonous pitohui birds may eat relatives of this beetle.
A kind of Asian grass snake called the tiger keelback uses poison taken from its prey for defense, too. The snake eats toads that are poisonous. Its body stores the poison in glands on its neck. When a predator threatens it, the snake does not flee. Instead, it tucks in its head to present the poison-filled glands. If the predator bites, it will get a mouthful of poison.
Some poisonous animals make their own poison. Others use poison made by other living things. Scientists have discovered that these animals are ableto eat poisonous meals and store the chemicals in their bodies for use in defense.
Monarch butterflies get their poison from milkweed plants, on which monarch caterpillars feed. Many kinds of milkweed make poison to defend themselves from plant-eating animals. The poison causes heart failure, and most animals avoid it. It does not, however, affect monarch caterpillars. As they grow, they stock up milkweed poison in their bodies. The poison remains after they turn into butterflies.
The foaming grasshoppers of Africa get their poison by eating milkweed, too. Other insects obtain poison from other plants. The garden tiger moth, for example, makes some of its poison but gets the rest from plants it eats as a caterpillar, such as poisonous foxgloves. Cinnabar moth caterpillars become poisonous by eating toxic ragwort plants. The caterpillar of the rattlebox moth also eats poisonous plants. The adult rattlebox moth, which has a warning coloration, is so distasteful that if it is caught in a web, the spider cuts it free.
Some insects get their poison by eating other poisonous insects. One kind of fire-colored beetleeats blister beetles and stores the defensive chemicals in its body. Some of the chemicals leak into a groove on its head. A femalefire-colored beetlewill accept a maleas a mate only if he has a good supply of these chemicals. He will give her some of the chemical, which she will then pass on to her eggs. The chemical repels ants and other insects that might eat the eggs.
Cochineal insects, which feed on cactuses in American deserts, also make a defensive chemical that is stolen by other insects. This chemical, a red acid, repels ants and most other insects. But some insects are not bothered by it. One kind of moth caterpillar eats cochineal insects, and then when a predator bothers it, the moth caterpillar throws up the acid along with its stomach contents. Ants that get slimed with this substance give up their attack. The larva of a species of ladybug also eats cochineal insects. Its body uses the bug’s acid as part of the beetle’s reflex-bleeding defense. The larvae of a fly species that eat cochineal insects excrete the acid to repel predators.
Other animals can eat poisonous bugs without being harmed, and then use the poison themselves. Poison dart frogs do not actually make their own poison; they get it from the insects they eat. Their most likely source is a beetle. Poisonous pitohui birds may eat relatives of this beetle.
A kind of Asian grass snake called the tiger keelback uses poison taken from its prey for defense, too. The snake eats toads that are poisonous. Its body stores the poison in glands on its neck. When a predator threatens it, the snake does not flee. Instead, it tucks in its head to present the poison-filled glands. If the predator bites, it will get a mouthful of poison.
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