Animal defences

If you want to drive someone away, then throwing up on them is probably going to do the trick. But the caterpillars of the small mottled willow moth (aka the beet armyworm; Spodoptera exigua) take defensive vomiting to a whole new level. Their puke is both detergent and chemical weapon; its goal is not to cause revulsion but to break through the waterproof layer that its predators find so essential. Willow moths are attacked by a variety of predatory ants. To study their defences, Rostas and Blassmann reared several caterpillars and exposed them to the European fire ant (Myrmica rubra).…
Many animals use poisonous secretions to protect themselves from predators. But poisons are complex chemicals and can take a lot of energy to make. Why invest in them, when you can steal someone else's? Poison thieves are well-known in the animal kingdom. Many species of brightly coloured poison arrow frogs acquire their poisons from beetles, while some sea slugs make a living by hunting for jellyfish, transporting their stinging cells into their own limbs. Now, another species joins this guild of thieves - the tiger keelback snake, Rhabdophis tigrinis (image right, by Deborah…
A caterpillar is an eating machine - a mobile set of mandibles, whose sole mission is to survive long enough to munch its way to adulthood. Standing in their way are spiders, birds and predatory insects that want to eat them, and parasitic wasps that want to convert them into living incubators for their own larvae. With so many enemies, defence is paramount for caterpillars and the various species have evolved a dazzling array of countermeasures. Some camouflage themselves, others use bright colours to advertise their toxic chemical weapons, which in at least one species is powerful enough…
The forests of east Asia are home to giant honeybees. Each one is about an inch in length and together, they can build nests that measure a few metres across. The bees have an aggressive temperament and a reputation for being among the most dangerous of stinging insects. Within mere seconds, they can mobilise a swarm of aggressive defenders to repel marauding birds or mammals. But against wasps, they use a subtler and altogether more surprising defence - they do a Mexican wave. Wasps, and hornets in particular, are major predators of bees and the largest ones can make even the giant bees…
In the X-Men comics, the superhero Wolverine is armed with three sharp claws on each arm. They extend through the skin of his hand, and the resulting wounds are closed by up his superhuman ability to heal. Now, in a bizarre case of life imitating art, scientists from Harvard University have discovered that a group of African frogs use similar weapons. The frogs defend themselves with sharp bone claws on their hind feet but to do so, the animals have to drive the claws through their own skin. It's an extreme defence that is completely unique in the animal world. The clawed frogs belong to a…
As far as humans are concerned, sexually-transmitted infections are things to avoid. But imagine if these infections didn't cause death and disease, but gave you superpowers instead. It may sound like a bizarre fantasy, but it's just part of life for aphids. Aphids mostly reproduce without sex, giving rise to many all-female generations that are exact copies (clones) of their parents. They only have sex once in autumn, the only time when mothers give birth to males. Asexual reproduction makes sense for aphid mothers since they pass on all of their genes to their daughters. If they…
Many animals have cunning ways of hiding from predators. But the larva of the sand dollar takes that to an extreme - it avoids being spotted by splitting itself into two identical clones. Sand dollars are members of a group of animals called echinoderms, that include sea urchins and starfish. An adult sand dollar (Dendraster excentricus) is a flat, round disc that lives a sedate life on the sea floor. Its larva, also known as a pluteus, is very different, a small, six-armed creature that floats freely among the ocean's plankton. A pluteus can't swim quickly, so there is no escape for one…