A true predator kills and eats another organism

In ecological terms predation is described as the interaction whereby one organism feeds on its prey. Predators may or may not kill their prey before eating them but the end result is beneficial to the predator and harmful to the prey. This has led to selective pressures on one another which have lead to an evolutionary arms race between the predator and prey resulting in various anti-predator adaptations.

Predators are usually classified by the way they feed and the way they interact with their prey. A true predator is one which kills and eat anther organism. It may hunt actively for its prey or sit and wait for it to approach within striking distance. Some predators such as the lion kill larger prey which they dismember and chew while others like dolphins eat their prey whole. Some predators like snakes poison their prey to subdue it or kill it before eating it.

Prey species have evolved several ways to avoid being preyed upon. One common form of defence is aggression. The electric eel uses an electric current to kill prey and to defend itself from other predators. Others animals use their tusks, horns and hoofs to defend themselves.

An interesting form of defence, common in birds, is mobbing. This is when animals attack and harass a predator to drive it away. This can be seen in many species of birds such as gulls which attach predator, including men, when these get anywhere near their nests.

Some animals are camouflaged to avoid being seen while others are brightly coloured and do not bother to hide themselves. Their colouration is recognised and remembered by predators as a danger signal and are left alone. These animals such as the ladybirds, wasps and the caterpillars of the spurge hawkmoths, are usually poisonous or bad tasting.

The humped crab spider is an aggressive predator that lives on flowers with which it easily blends. It prefers the large yellow flowers of the crown daisy, which are now in flower. It lies motionless in wait for an insect to land on the flower and then catches it with its forelegs. It bites it to inject a poison and holds on to it until it is paralysed or dead before it starts to suck its body. 

This article was published in The Times on 20.01.2010