Mimicry is a survival technique practised by all living organisms including humans. Humans use manufactured materials to mimic and camouflage themselves; the non-human world is all about being organic. The animal kingdom abounds with numerous examples of mimics that share our spaces, confuse us so well that either we miss them or mistake them – because they are such good mimics. I introduce you to those that are common examples in a biology lesson, yet hidden among them are also some uncommon ones that can be completely missed if one is not alert and observant.
The praying mantis that is not a stick insect
Stick and leaf insects are the most common examples given to students in a biology class. Yet I wonder how many have actually seen a stick insect to be able to recognize one, or even less a leaf insect. Probably a bleached specimen inside a formalin filled jar or a garish image in a book. So teachers, take your students out and try this fun-filled classroom activity, I have titled as “Insect Cons”
A common insect in most habitats across India, especially South India, is this preying mantis that is often mistaken to be a stick insect. It is only in external appearance that it looks like a stick insect. A closer examination will reveal that its front pair of legs is held up folded together in the classical ‘praying position’ that gives mantids the other common name, i.e., praying mantis. Observation will also reveal other features, several spines on the front pair of legs that are never there on a stick insect. The way the legs are held by a stick insect is quite different from the way a praying mantis holds its leg. Another feature is the head. Quite distinct and different in shape and the way they are articulated and held can clearly tell you whether you are looking at a mantid or a stick insect. This preying mantis is a common visitor to most gardens. The stick insect is not so easily seen. Many of them are nocturnal creatures, best seen at night when they emerge to feed or at dawn or dusk. Stick insects can also pretend to be dead if they sense danger. This kind of deception is known as thanatosis.
A longhorned grasshopper that is not a leaf insect
The grasshopper is a well-known insect in biology classes and it is shown in textbooks coloured green. For insects that graze on leaves it is a safe colour for camouflage which is why many phytophagous insects sport green. But some are not satisfied with mere camouflage and add a dash of mimicry to hide themselves. Some make themselves look like leaves. Ask students to give you features that they would expect to see on a leaf insect. Lest they forget, remind them that a leaf insect is an insect and so their description must match closely with the basic body structure of an insect. Let not their imagination run away with them. Now show them the two images that are given here and ask them what they would call these two insects.
The author is a consultant for science and environment education. She can be reached at firstname.lastname@example.org.