Question

Insect legs modification​

Answer 1

Answer:

Explanation:

NSECT LEG AND IT’S MODIFICATION ARUN KUMAR K M I Ph.D. Agricultural Entomology UAS, GKVK, Bengaluru

2. Insect leg Structure: • In almost all insects all the three thoracic segments viz., pro-, meso- and metathorax bear a pair of segmented legs. • Each leg consists of five segments viz., coxa, trochanter, femur, tibia and tarsus.

3. 3 Insect leg Trochanter Coxa Femur Tibia Tarsus Pretarsus

4. • Coxa : (Pl. coxae) It is the first or proximal leg segment. • It articulates with the cup like depression on the thoracic pleuron. • It is generally freely movable.

5. • Trochanter: It is the second leg segment. • It is usually small and single segmented. • Trochanter seems to be two segmented in dragonfly, damselfly and ichneumonid wasp.

6. • Femur: (Pl. femora) It is the largest and stoutest part of the leg and is closely attached to the trochanter.

7. • Tibia: (Pl. tibiae) It is usually long and provided with downward projecting spines which aid in climbing and footing. Tibia of many insects is armed with large movable spur near the apex.

8. • Tarsus: (Pl. tarsi) It is further sub-divided. The sub segment of the tarsus is called tarsomere. • The number of tarsomeres vary from one to five. The basal tarsal segment is often larger than others and is named as basitarsus.

9. Pretarsus: • Beyound the tarsus there are several structure collectively known as pretarsus. • Tarsus terminates in a pair of strongly curved claws with one or two pads of cushions at their base between them. • A median pad between the claws is usually known as arolium and a pair of pads, at their base are called pulvilli (Pulvillus-singular). • Leg pads are useful while walking on smooth surface and claws give needed grip while walking on rough surface. When one structure is used, the other is bent upwards.

10. Types or modifications Legs are modified in to several types based on the habitat and food habit of insect and used for a wide variety of functions

11. Ambulatorial (Ambulate - to walk; Walking leg) e.g. Fore leg and middle leg of grasshopper. Femur and tibia are long. Legs are suited for walking.

12. Cursorial: (Cursorial = adapted for running : Running leg) e.g. All the three pairs of legs of cockroach. Legs are suited for running. Femur is not swollen.

13. Saltatorial: (Salatorial = Leaping : Jumping Leg) e.g. hind leg of grasshopper.

14. Scansorial: (Scansorial = Climbing; climbing or clinging leg) e.g. all the three pairs of legs of head louse.

15. Fossorial: (Fossorial = Digging; Burrowing leg) e.g. Fore legs of mole cricket.

16. Raptorial: (Raptorial = predatory ; Grasping leg) e.g. Forelegs of preying mantis.

17. Natatorial: (Natatorial = pertaining to swimming; Swimming leg) e.g. hing legs of water bug and water beetle.

18. Sticking leg: e.g. all the three pairs of legs of house fly.