Environmental Problems, Their Causes, and Sustainability 1

Other predators use camouflage—a changein shape or color—to hide in plain sight andambush their prey. For example, praying mantisessit in flowers of a similar color and ambushvisiting insects. White ermines (a type ofweasel) and snowy owls hunt in snow-coveredareas. The alligator snapping turtle, camouflagedin its stream-bottom habitat, dangles itsworm-shaped tongue to entice fish into its powerfuljaws. People camouflage themselves tohunt wild game and use camouflaged traps toambush wild game.Some predators use chemical warfareto attack their prey. For example, spidersand poisonous snakes use venom to paralyzetheir prey and to deter their predators.(a) Span worm(b) Wandering leaf insectHow Do Prey Defend ThemselvesAgainst or Avoid Predators? Escape,Repel, Deceive, and PoisonSome prey escape their predators or haveprotective shells or thorns, some camouflagethemselves, and some use chemicals to repel orpoison predatorsPrey species have evolved many ways to avoidpredators, including the ability to run, swim, orfly fast, and a highly developed sense of sight orsmell that alerts them to the presence of predators.Other avoidance adaptations are protectiveshells (as on armadillos, which roll themselvesup into an armor-plated ball, and turtles), thickbark (giant sequoia), spines (porcupines), andthorns (cacti and rosebushes). Many lizardshave brightly colored tails that break off whenthey are attacked, often giving them enoughtime to escape.Other prey species use the camouflage ofcertain shapes or colors or the ability to changecolor (chameleons and cuttlefish). Some insectspecies have evolved shapes that look like twigs(Figure 8-9a), bark, thorns, or even bird droppingson leaves. A leaf insect may be almost invisibleagainst its background (Figure 8-9b), andan arctic hare in its white winter fur blends intothe snow. A spotted cheetah blends into thegrass as it watches for grazing animals to chasedown and kill.Chemical warfare is another common strategy.Some prey species discourage predatorswith chemicals that are poisonous (oleander plants), irritating(stinging nettles and bombardier beetles, Figure8-9c), foul smelling (skunks, skunk cabbages, andstinkbugs), or bad tasting (buttercups and monarchbutterflies, Figure 8-9d). When attacked, some species(c) Bombardier beetle(e) Poison dart frog(g) Hind wings of Io mothresemble eyes of a muchlarger animal.(d) Foul-tasting monarch butterfly(f) Viceroy butterfly mimicsmonarch butterfly(h) When touched,snake caterpillar changesshape to look like head of snake.Figure 8-9 Some ways in which prey species avoid their predators by (a, b)camouflage, (c–e) chemical warfare, (d, e) warning coloration, (f) mimicry,(g) deceptive looks, and (h) deceptive behavior.of squid and octopus emit clouds of black ink to confusethe predator and allow them to escape.Scientists have identified more than 10,000 defensivechemicals made by plants. Some are herbivorepoisons such as cocaine, caffeine, cyanide, opium,http://biology.brookscole.com/miller14153