Predator-Prey Strategies

1. Predator-Prey Strategies Biological Science 3 2011

2. Strategies for Avoiding Predators • Poisons • Mimicry • Visual deception • Chemical defenses • Offensive weapons • Camouflage • Size

3. Poisons • Poisonous organisms often have bright colours to warn predators away. • Examples: frogs, some butterflies, some plants.

4. Mimicry • Batesian mimicry- a harmless species which resembles a poisonous or unpalatable species. • Mullerian mimicry- two unpalatable species which resemble each other.

5. Visual Deception • Markings deceive predators, allowing the prey to escape. • ‘Eye’ markings on fish encourage predators to strike at the wrong end of the fish. • The ‘eye’ markings on this moth resemble an owl.

6. Chemical Defenses • Noxious smelling chemicals discourage predators. • Example: skunks.

7. Offensive Weapons • Offensive weapons allow prey to actively fight off predators. • Antlers • Teeth • Claws

8. Camouflage • Camouflage (cryptic colouring) allows prey to hide from predators.

9. Size • Very large organisms are generally too large to be vulnerable to predators

10. Strategies for Catching Prey • Concealment • Filter feeding • Tool use • Stealth • Lures • Traps

11. Concealment • Some predators use camouflage to conceal them while they stalk the prey.

12. Filter Feeding • Filter feeders take in a large volume of water and strain it out, retaining small organisms in the water. • Examples: flamingoes, Baleen whales.

13. Tool Use • Some species use tools to access their prey. • Examples: primates using sticks to reach ants.

14. Stealth • Snakes use their ability to sense infrared to hunt at night.

15. Lures • Angler fish use lures to attract prey within striking range. • Examples: angler fish, some spiders.

16. Traps • Spiders create webs which trap prey (typically insects).

17. Relationships between Predators and Prey • The numbers of prey and predators are linked. • Following an increase in prey numbers, there is a corresponding increase in predator numbers.

18. Questions • What is the difference between passive and active predator avoidance strategies? • Only the males of most deer species have antlers. Explain why. • How could the large fake eyes seen on some butterflies evolve? • Explain how Batesian mimicry benefits the mimic. • Mature fur seals are a dark colour, while the pups are white. Explain the reason for these different colours. • Explain the cyclic dip in snowshoe hare & lynx numbers.