Grasshoppers

August 5, 2010 by  


science 08-02-10

The grasshopper is an insect of the suborder Caelifera in the order Orthoptera. To distinguish it from bush crickets or katydids, it is sometimes referred to as the short-horned grasshopper. Species that change colour and behaviour at high population densities are calledlocusts.

Grasshoppers haveantennae that are almost always shorter than the body (sometimes filamentous), and shortovipositors. They also have pinchers ormandibles that cut and tear off food.[1] Those species that make easily heard noises usually do so by rubbing the hind femurs against the forewings or abdomen (stridulation), or by snapping the wings in flight. Tympana, if present, are on the sides of the first abdominal segment. The hind femora are typically long and strong, fitted for leaping. Generally they are winged, but hind wings are membranous while front wings (tegmina) are coriaceous and not fit for flight. Females are normally larger than males, with short ovipositors. Males have a single unpaired plate at the end of the abdomen. Females have two pairs of valves ( triangles) at the end of the abdomen used to dig in sand when egg laying.

They are easily confused with the other sub-order of Orthoptera, Ensifera, but are different in many aspects, such as the number of segments in their antennae and structure of the ovipositor, as well as the location of the tympana and modes of sound production. Ensiferans have antennae with at least 20-24 segments, and caeliferans have fewer. In evolutionary terms, the split between the Caelifera and the Ensifera is no more recent than the Permo-Triassic boundary (Zeuner 1939).

The digestive system of insects includes a foregut (stomodaeum, the mouth region), a midgut (mesenteron), and a hindgut (proctodaeum, the anal region). The mouth leads to the muscular pharynx, and through the esophagus to the crop. This leads to the malpighian tubules. These are the chief excretion organs. The hindgut includes intestine parts (including the ileum and rectum), and exits through the anus. Most food is handled in the midgut, but some food residue as well as waste products from the malpighian tubules are managed in the hindgut. These waste products consist mainly of uric acid, urea and amino acids, and are normally converted into dry pellets before being disposed of.

The salivary glands and midgut secrete digestive enzymes. The midgut secretes protease, lipase, amylase, andinvertase, among other enzymes. The particular ones secreted vary with the different diets of grasshoppers.

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