9.4: Predation

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Bears catching fish and a kookaburra ambushing a frog (Figure \(\PageIndex{1}\), left and middle) are simple kinds of predation. Other ambush strategies are also common. The stonefish (right) is disguised to match its background and waves a lure to attract other fish, who are then instantly swallowed whole. Despite hundreds of millions of years of evolution, the trick still works.

Predation ch9.JPG — Figure \(\PageIndex{1}\). *Predation.*

Cats typically pursue ambush strategies, lying in wait (Figure \(\PageIndex{2}\), left), whereas dogs typically pursue sustained chasing strategies. This means that cats must be relatively odorless to avoid detection, but dogs need not be.

Ambush predation.JPG — Figure \(\PageIndex{2}\). *Ambush predation.*

In a curious ambush strategy only recently achieved, herons wave gathered feathers to attract fish, then drop the feathers and grab the fish (Figure \(\PageIndex{2}\), right). Such use of feathers is apparently an animal “meme” that has spread rapidly through heron populations after being discovered by some Einstein-heron.

Predation and parasitoidism.JPG — Figure \(\PageIndex{3}\). *Predation and parasitoidism.*

Species interactions can lead to remarkable evolutionary adaptations, including the non-messy way of eating an egg (Figure \(\PageIndex{3}\) left).

Nature acknowledges neither kindness nor cruelty, but parasitoidism seems one of the cruelest strategies (Figure \(\PageIndex{3}\), right). Here an Ammophilia wasp is carrying a caterpillar not to kill and eat, but as a living hatchery for her eggs. Young wasps developing from these eggs consume the caterpillar from within as the caterpillar remains alive, transforming it into wasp larvae. Parasitoidism is widespread.

When the predator is small relative to the prey, predator– prey interactions are called “parasitism.” At left in Figure \(\PageIndex{4}\) is a blood-sucking mosquito attached to an unfortunate human. At right is a beetle seemingly overwhelmed with mites. When the predator is much smaller still, it is called a “pathogen” and the interactions are called “infection” and “disease.”