About Lesson
Modification of legs
- Fossorial or digging:
- The legs modified for digging are best known in mole crickets (Gryllotalpa africana) and dung beetles.
- In Gryllotalpa, the forelegs are very short and broad, the tibia and tarsomeres bearing stout lobes which are used in digging.
- Cursorial or walking-running type:
- Cursorial legs tend to be long and narrow and are designed so that the insect can move very quickly.
- It has five segmented tarsus, both femur and tibia bears spines. Example: mesothoracic legs of cockroach, Periplanteta amenricana, ground and tiger beetles (order Coleoptera).
- Saltatorial or jumping type:
- Hind Femur is greatly enlarged.
- Saltatorial legs work well for jumping because they are enlarged legs filled with bulky, strong muscles.
- All those muscles allow insects with this type of leg to jump, propelling themselves forward very long distances very quickly.
- Example: hind legs of grasshopper, Hieroglyphus banian.
- Raptorial or grasping legs:
- Coxa is elongated, femur and tibia bear rows of spines.
- This type of leg modification is found in predatory insects and helps in catching the prey. Example: the forelegs of praying mantids, Mantis religiosa and water scorpion.
- Natatorial or swimming:
- Insects with natatorial legs are aquatic insects that require modified legs to move easily through water.
- Coxa is long, tibias and tarsi bear hears and flattened to form an oar like structure for swimming. Example: the hind legs of water scavenger beetle.
- Scansorial or clinging type:
- Tarsus is single segmented and terminated into a powerful claw for clinging. Example: fore legs of body louse, Haematopinus suis.
- Polleniferous or pollen carrying:
- The femur and tibia of hind legs are provided with brush like hairs, the tibia is broadened with concave outer surface fringed with long curved spines and acts as pollen basket.
- A comb in the inner side of pretarsus is used for pollen collection.
- A rake at the base of tibia is used for scrapping and collecting pollen in the pollen basket. Example: the workers of Apis mellifera.