SCIENCE LAB SPECIAL : TAILORING ITS TOXINS

 

Giant redheaded centipede reveals a surprising variety of venom recipes : A giant centipede's many wriggling legs might be creepy. But the pair of legs not used for walking may be the most frightening.

More than 430 million years ago, the two legs nearest the mouth evolved into sharp pincers that contain venom glands. Within these glands are microscopic factories capable of manufacturing multiple toxic compounds.

Just like spiders, giant centipedes use these tools to hunt prey - including crickets and snakes. But giant centipedes also make for a juicy snack for other animals, forcing them to defend themselves with the same poisonous pincers.

In a paper published in the journal. Nature Ecology & Evolution, scientists revealed that the redheaded centipede - a species of giant centipede roughly the length of a ballpoint pen - is a toxic mixologist, capable of tailoring its venom recipe depending on whether it's attacking prey or defending itself.

The toxins reserved for the centipede's predators appear designed to cause pain, the researchers found.

The findings may also hint that venom produced by other animals might be more complex than were previously understood.

To collect venom, scientists most often zap an animal with a nonlethal amount of electricity. The pulses contract the animals' muscles, which squeeze out the venom.

It had been believed that this technique released venom with all its toxic molecules, said Vanessa Schendel, a venom biologist at the University of Queensland in Australia and an author of the new study.

Dr. Schendel gathered centipede venom using electricity, but she also tried something bolder : She picked up centipedes to mimic a predatory attack and collected the venom that they secreted.

When the team analyzed the toxins in venom collected using the two methods, they found surprising molecular differences. This means that neither venom held all the toxins centipedes produce.

'' I thought there was something wrong,'' Dr. Schendel said. But the pattern held across multiple experiments. [ Andrew Chapman ]