Creatures such as the tarantula and the Gila monster are nightmares of myth and legend -- but also a surprising treasure trove for medical science.

The oceanic whitetip shark is infamous for attacking shipwreck survivors. On land, packs of feral dogs are becoming a serious threat to human life.

The boa constrictor crushes the life out of its victims and the bullet ant's sting is painful, but the assassin caterpillar lives up to its name.