information on catterpillar?

Answer 1

A caterpillar is the larval form of a lepidopteran (a member of the insect order comprising butterflies and moths).

Caterpillars have long segmented bodies. They have six true legs, up to four pairs of prolegs on the middle segments of the abdomen, and sometimes a single pair of prolegs on the last abdominal segment. Sawfly larvae (Hymenoptera) superficially resemble caterpillars, but can be distinguished because they have prolegs on every abdominal segment, whereas the true caterpillar does not. Another difference is that lepidopteran caterpillars have crochets or hooks on the prolegs. Thus, true caterpillars always have a few abdominal segments lacking prolegs, in some cases several, or even all segments may lack them. The geometrids, also known as inchworms or loopers, are so named because of the way they locomote, appearing to measure the earth (the word geometrid means earth-measurer in Greek), but the primary reason for this unusual locomotion is the elimination of nearly all the prolegs.
Caterpillars do not breathe through their mouths. Air enters their bodies through a series of small tubules along the sides of their thorax and abdomen. These tubules are called spiracles, and inside the body they connect together into a network of airtubes.

Caterpillars do not have very good eyesight or senses. Rather than having fully-developed eyes they have a series of six tiny eyelets or stemmata on the lower portion of their head. They rely on their antennae to help them locate food. The larvae of sawflies differ from true caterpillars in this respect, as well, as they have prominent ocelli on the head capsule.

Defence

Many species of birds and animals consider caterpillars as protein rich food, and caterpillars have evolved various defenses. These methods can be either passive, aggressive, or both. Some caterpillars have large false eyes towards the rear of their abdomen. This is an attempt to convince predators that their back is actually their front, giving them an opportunity to escape to the 'rear' when attacked. Others have a body coloration that closely resembles their food plant.

More aggressive self-defence measures are taken by the spitfires and hairy caterpillars. These caterpillars have spiny bristles or long fine hairs that will irritate anything that brushes against them, or spit acidic digestive juices at potential enemies. However, some birds, like cuckoos, will swallow the hairiest of caterpillars.

The most aggressive defenses are those of the many caterpillars that have bristles associated with venom glands, called urticating hairs, and some of these are among the most potent defensive chemicals in any animals; e.g., the defensive chemical produced by the South American silk moth genus Lonomia is an anticoagulant of such potency that it can kill a human, causing them to hemorrhage to death (see Lonomiasis; [1]) This chemical is being investigated for potential medical applications (i.e., to prevent blood clotting).

Some caterpillars eat the leaves of plants that are toxic to other animals. They are unaffected by the poison themselves, but it builds up in their system, making them highly toxic to anything that eats one of them. These toxic species, such as the Cinnabar moth (Tyria jacobaeae) caterpillars, are brightly striped or coloured in red and yellow—the danger colours (see aposematism).

The aim of all these aggressive defense measures is to assure that any predator that eats (or tries to eat) one of them will avoid future attempts.

Some caterpillars obtain protection by associating themselves with ants. The Lycaenid butterflies are particularly well known. Recent findings have shown that they communicate with their ant protectors by means of vibrations as well as chemical means.


Behaviour
Life cycle of the red-humped caterpillar (Schizura concinna)

Caterpillars have rightfully been called eating machines. They eat leaves voraciously, shed their skins generally four or five times, and eventually pupate into an adult form. Caterpillars have the fastest growth rate of any animal in the world. For instance, a tobacco hornworm will increase its own weight ten thousand times in less than twenty days. One of their adaptations that enables them to eat this much is a mechanism in a specialized midgut which transports ions at a very high rate to the lumen (midgut cavity), to keep the potassium level higher in the midgut cavity than in the blood. This mechanism is not found in any vertebrates.

Some Hawaiian caterpillars use techniques similar to spiders to hunt their prey of snails. [1]

Other carnivorous species of caterpillars are also known, but still represent a tiny fraction of all known representatives of these insect larvae.
Source: wikipedia

Answer 2

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