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, and both the femur and tibia bear spines. Example: mesothoracic legs of cockroach, Periplanteta Americana, ground,a nd 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 a grasshopper, Hieroglyphus banian.
- Raptorial or grasping legs:
- The coxa is elongated, femur and tibia bear rows of spines.
- This type of leg modification is found in predatory insects and helps in catching 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 the water.
- Coxa is long, tibias and tarsi bear ears and flattened to form an oar-like structure for swimming. Example: the hind legs of the 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 a brush like hairs, the tibia is broadened with a concave outer surface fringed with long curved spines and acts as a pollen basket.
- A comb in the inner side of the pretarsus is used for pollen collection.
- A rake at the base of the tibia is used for scrapping and collecting pollen in the pollen basket. Example: the workers of Apis mellifera.
