ADAPTIVE COLOURATION

Adaptive colouration is the possession by an organisms, of a colour which enable it to catch its preys, avoid its predators or enemies and ensure its survival. In order to obtain food, escape or hide from their enemies and secure mates, many organisms possess attractive colours and special patterns or markings on their bodies. Both plants and animals exhibit adaptive colouration.

 

Examples of adaptive colouration in animals

1) Warning colouration: A warming colouration is one that scares away the animal’s enemies or predators. The attractive colouration of some animals serves as a warming to predators that they are unpalatable. Their distinctive colours or markings protect them from attack. For examples:

• the black and yellow colour of variegated grasshopper.
• the black and yellow bands of wasps.
• the lady birds (beetle).

 

2) Batesian mimicry: Batesian mimicry is a condition in which a harmless organism resembles a distasteful or harmful one so that its enemies would avoid it. In other words, mimicry is the resemblance of an animal called a mimic to another different object, the model, in order to increase its chances of survival. For example, a palatable animal is protected from its predator by resembling (mimicking) a distasteful species with warning colouration. Mimics obtain protection by looking like dangerous or distasteful organism which they are naturally unrelated. Examples are:

• The swallow-tail butterfly has red colouration on the wing like a distasteful one.
• The stick insect resembles dead twigs.
• The katydid, a grasshopper which mimicks a living leaf.

 

3) Camouflage: Camouflage is a concealing colouration which matches the colour of the background. Many animals are protected from their predators by the close matching of their body appearance with their surrounding background. Examples:

• Grasshoppers have green pigments in their cuticles.
• Green snakes also have green pigments on their skin.

This green colouration of the body makes it difficult for their enemies to recognise them within green grasses.

 

4) Mating colouration: The conspicuous skin colouration in the adult males help the adult females to select males of their own species for mating. This enables the products of such mating to survive.

 

5) Counter shading: Counter shading is the possession of two distinct colour (dorsal and ventral) by some organisms to match the colours of their environment such that when the organism is viewed by its predator from above or below, it cannot be seen. Animals with such different colours are said to be counter shaded.

In Tilapia fish for example, the dark dorsal colour tends to blend with dark coloured water bottom and the silvery white ventral surface blends with the sky colour above them. This protects them from predators looking at them from above or below.

 

6) Changing of body colour: This is the ability of some organisms to change the colour of their body to look like that of the environment. For example, the chameleon can change its body colour in seconds to look like the environment. The grasshoppers can also change their colours from green in the rainy seasons when the grasses are green to brown in the dry season when the grasses are brown. These colour changes in the body to resemble that of the environment conceal these animals from being noticed by their enemies or predators.

 

Adaptive Colouration in Plants

Some plants also have adaptive colouration which enable them to carry out specific functions such as:

1. Pollination: Many insect-pollinated flowers are brightly coloured so as to attract insects that pollinated the flowers.
2. Feedings: Some insectivorous plants such as nepenthes and saracenia have brightly coloured pitchers which attract insects that may fall into the pitchers, drown in the liquid in them and get digested.