Types of legs adapted to diverse habitat:
The adaptive radiation amongst insect is well wilness from a wide range of modifications. That occurs in structural organization of legs. In accordance with the mode of life, insects are adapted to perform various
Types of locomotion walking , running , leaping , clasping , swimming & clinging etc. The legs in some insects are modified for digging the burrows , transporting food material & for catching the prey . On the basis of structural organization & function insects legs can be classified into following types:
Ambulatory legs :-The legs are adapted for walking . They are characterised by having flattened femore long tilua & well defined femortibial joint. The pretarsi are provided with long claws a flattened arolia to enable the insect to move perfectly on even rough surfaces. Eg- Dermaptera , some beetles.
The cursorial legs :- The legs are elongated thin & tubular with a flattened femora highly muscular coxa , with a slender & elongated tibia & tarsi . The modifications bring an efficient running
Eg – Corcrroaches , Tiger beetles
The saltatorial :- This types of legs are modified for leaping or jumping . In the grasshoppers & crickets & coleopteran . Halictinal the femoro of hind loop are greatly enlarged to ledge strong levator which bring leaping movement. The promixal margin of femona bears dorsal cuticular process. The intrinsic articulation notches are well developed. The femorotibal articulation is provided with a large membranes area. The tibia including its base is dorsoventrally wrapped by a membranes . The extrinsic articulation of tarsus with tarsus is with elaborated into na monocondylic joint. The trochanter is
the most modified structure . It is reduced into a sclerotic ring concealed under the proximal end of the
femur & is firmly fused with the metaferum so that the trochantoro femoral joint is non removal.
The Natatorial legs :-In aquatic insects , the modified for swimming . The modification however differ
among different groups of insects . The coreids bear foliate processes on the hind femora & tibiae . The
aquatic bugs can swim with the help of long hairs developed on the mid & hind-legs . In the notonectids , only the hind legs are notatory . In gessids , the middle tars bear complex plumose setae enabling them to swim on water.
The clasporial legs :- In true lice, mallophagan & siphunculata a single segmented tarsus bears a long
hook-like curved claw with ventral pad. The claw opposes the tibial procers so that the body hair can be
firmly held as an adaptation of ectoparasitic mode of life. The forelegs of some aquatic beetles are provided with the suckers on the metalarsi & stumpy tarsomeres in males for holding the fmales during
mating . eg. The male beetles of the families , ditiscidae , hydrophilic , carabidae , cicindelidae The Raptorial legs :-The forely of mantids & some aquatic bugs & hind legs of same parasitic hymenoptera flies are modified into the prehensile organs for catching the prey. The legs are elongated & spiny . In the mantids the tibia can be accommodated into the groove of the femur & the tursus can be inserted into the apical hook of femur . The femora , tibial joint is well doped . The foretibia of the bug , Naucoria is modified into a single arrow like pointed structure.
Fossorial legs :- The forelegs of the gyllotalpidae & cylindrichotidae among orthoptera & the nymphs of cicada represents fossorial modification . The foretibia are broad , highly sclerotized , stumpy with
terminal digital processes pr teeth while the tarsi & pre tarsi are completely reduced . The foretibial digital processes are used for digging as insects are adopted to the subtersanear habit. In the scarafid butleo the tibiae are toothed & are used in excavation.
The corbiculate legs:- Legs of type are well evident in the honey bees and the dragonflies . The forelibia bear a terminal spur known as the known as the fibula , the calcar which can be accomodated
into a proximal cavity of tarsi . The antennae are inserted through this cavity so that the attached pollens
on the antennae can be removed by the fire hairs of the cavity .These pollen grains are collected & carried out in the basket or corbicula formed by the combs of metatarsal setae of both the hind legs . The combs are also known as the scope. The legs of dragonflies are often directed forward as a result of unique modification of thorax . The legs can cover the mouth parts & tarsi are provided with long soines & bristles . These bristles or spines of the legs of one side combine with these of other side & form a sort of finely nelted basket for trapping , collecting & transporting the mosquitoes etc.
Degeneration of the legs :-…