In the cut-throat animal kingdom, some animals have powerful chemical weapons to increase their chances of survival. Over 3000 varieties of nudibranchs, known as sea slugs, are found around the world in diverse ecosystems. The are able to breath through external plumes, and their defense includes chemo-reception, poison-filled barbs, and cross-fertilization. Assassin bugs also use deadly venom to survive. Some members of this group even prey on humans, but some are a benefit to farmers. In tropical seas, the iridescent cuttlefish also delivers lethal poison to catch its prey. Highly evolved, they adapt to new environments quickly with eyes that can detect polarized light, toxic saliva that can paralyze larger prey, and advanced camouflage techniques. Finally, the red-headed centipede has 42 sharp sticky legs and venom filled fangs which instantly paralyze larger prey in the American south.