Sunday, March 24, 2013

The slant-faced grasshopper

The Mediterranean slant-faced grasshopper is a slim, delicate grasshopper with a cone-shaped face and triangular antennae. It lives either humid or dry habitats with vegetation or sand in which it is very well camouflaged. It can be found between mid-summer and early autumn in many parts of the Mediterranean including Malta.

Many species of grasshoppers, including the slant-faced grasshopper which is known in Maltese as ġurat ta’ rasu twila, have two colour forms as they can be either green or brown. 

These colours allow these insects to disappear in their surroundings. This is one of the most common forms of cryptic colouration known as camouflage. 

More than anything else the success of good cryptic coloration is to break the outline of a creature’s body. Many species of insects and other creatures including fish, reptiles and mammals use camouflage as a means of defence.

The type of camouflage a species will develop depends on several factors. The most important factor is the environment in which the species lives. Another important factor is the physiology and behaviour of the animal. Furred animals need different camouflage than those with feathers or scales. 

The nature of the predator also makes a difference. Thus if the predator does not see colours the animals will not need to match the colour of its surroundings. Cryptic coloration can change as well in response to changes in the environment such as some foxes and the weasel that become white in winter so as to be able to disappear in the snow. Some insects including many grasshoppers are green during the wetter months while the generation that hatches during the hotter months would be brown. 

It is believed that the temperature of the egg determines the colour of the adult insect. 

Warmer eggs produce brown insects which would blend with the dry vegetation. 

This artcle was published in The Times on 7 October 2009.

No comments:

Post a Comment