Insect Leg

Insect Leg

• 1.
  Insect Leg Structure andModification @Bhubanananda Adhikari
• 2.
  Insect legs aretypically segmented type Legs are present in pro, meso and metathoracic segments Each leg consists of 5 segments 1. Coxa 2. Trochanter 3. Femur 4. Tibia 5. Tarsus Pretarsus Legs are modified into severaltypes based on habitat and food habit @Bhubanananda Adhikari Legs of Insect
• 3.
   First orproximal leg segment  It is freely movable and attached with thoracic pleuron @Bhubanananda Adhikari 1. Coxa (Pl. Coxae) Legs of Insect 2. Trochanter Second segment of leg which is small and single segmented Seems to be 2 segmented in dragonfly, damselfly etc The apparent 2nd trochanter is called “trochantellus” (actually a part of femur)
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  Largest and stoutestpart of leg closely attached to trochanter. @Bhubanananda Adhikari 3. Femur Legs of Insect 4. Tibia Long and provided with downward projecting spines (help in climbing and footing). Tibia in many insects armed with large movable spurs near apex 5. Tarsus Segmented structure, Individual segment known as tarsomere (1-5) except in protura, diplura and some larval forms. Basal tarsomere is larger and called basitarsus
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  @Bhubanananda Adhikari Legs ofInsect Pretarsus It is the 6th segment or last part of legs representing the foot. It is characterized by possessing a pair of terminal little curved, claws. The claw is also known as ungues. The tarsus at its end consists of pretarsus which is in the form of a pair of claws and cushion like pulvilli. The pulvilli bear a large number of pores and hairs which secreate the adhesive secreation that help in walking on the slippery surfaces. In between the claws, if there is lobe like structure, it is known as “aroleum” as in Orthoptera (grass hopper). If bristle like structure, it is called “empodium” as in Diptera.
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  Adapted for walking Femurflat, long tibia & well defind femoro- tibial joint. It can move perfectly on smooth & rough surfaces Ex- Dermaptera, Bugs, some beetles, Fore and middle legs of grasshopper @Bhubanananda Adhikari 1. Ambulatorial (Walking) leg
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  Adapted for running Thin& tubular with flattened femur Highly muscular coxa Tibia & tarsi slender & elongated Ex- Cockroach, Tiger beetle @Bhubanananda Adhikari 2. Cursorial (Running) leg
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  Adapted for leapingor jumping Trochanter fused with femur. Femur is enlarged to accommodate powerful extensor muscles of tibia Long and slender tibia with two rows of spines along the ventrolateral edges At tibial end, four spurs are fopr gaining grip against substratum. Ex- Hind leg of Grasshoppers, Crickets @Bhubanananda Adhikari 3. Saltatorial (Jumping) leg
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  Adapted for clinging Singlesegmented tarsus bears a long hook like curved claw with ventral pad. Tibia possess a thumb like fleshy lobe at its apex  Ex-head louse, body louse, bird lice (Mallophaga) @Bhubanananda Adhikari 4. Scansorial (Climbing or Clinging) leg
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  Adapted for digging Forelegs/front legs are modified for digging into the soil & for cutting the roots inside the soil Front tibia & tarsus are modified for this purpose. They are flattened & as shaped like shovels Coxa, trochanter & femur are short & strong but not modified Front tibia is divided in to server finger like branches & each branch is modified into strong pointed tooth like lobe are used for digging  Ex-Mole cricket, Nymphs of Cicade @Bhubanananda Adhikari 5. Fossorial (Digging) leg
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  Forelegs are forcapturing the prey, not used for locomotion Coxa is long and mobile (helps in capturing prey) Femur is large and grooved along the ventral surface with spines Spiny tibia fits into femoral groove when it snaps down over the prey Tarsus consisting of 5 tarsomeres  Ex- Forelegs of preying mantids @Bhubanananda Adhikari 6. Raptorial (Grasping) leg
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  Hind legs areadapted for swimming Femur, tibia, and first four tarsomeres are broad and flattened. Edges are provided with flattened setae  Ex- Hind legs of water bug and water beetle @Bhubanananda Adhikari 7. Natatorial (Swimming) leg
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  Pairs of lateraladhesive pads under claw called pulvilli Arolium is absent but median spine like structure empodium is present Pulvilli covered with glandular tenant hairs. Secretions of these tenant hairs help the insect I walking and clinging to smooth surface  Ex- All legs of housefly @Bhubanananda Adhikari 8. Sticking leg
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  Legs are situatedjust behind the head and are anterior in position Legs are spiny and closely placed useful for seizing the prey and captured insects are kept in the leg basket. vesicle- Modified arolium Legs are not useful for locomotion.  Ex- Legs of dragonfly and damselfly @Bhubanananda Adhikari 9. Basket like leg
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  The forelegs ofsame aquatic beetles are provided with suckers on the metatarsi & stumpy tarsomers in males for holding the female during mating. Tarsus id flattened with adhesive disc A viscous secretion from the sucker in the tarsus is discharged so that they adhere to surfaces they are applied. @Bhubanananda Adhikari 10. Suctorial (Clasping) leg
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  Thick, fleshy andnot segmented (found in caterpillar, 2-5 pairs) They are shed with larval moult Tip of proleg is called planta, clawas are known as crochets Last pair of abdominal proleg is Clasper.  Ex- Abdominal legs of caterpillar @Bhubanananda Adhikari 11. Prolegs/ False legs/ Pseudolegs
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  Corbiculate legs Ex- Alllegs of honeybee Fore legs (Eye brush, Antenna cleaner, Pollen brush) Middle legs (Pollen brush, Tibial spur) Hind legs (Pollen basket, pollen packer, pollen comb) @Bhubanananda Adhikari 12. Foragial (Food collecting) leg
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  Corbiculate legs Ex- Alllegs of honeybee Fore legs (Eye brush, Antenna cleaner, Pollen brush) Middle legs (Pollen brush, Tibial spur) Hind legs (Pollen basket, pollen packer, pollen comb) @Bhubanananda Adhikari 12. Foragial (Food collecting) leg
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  Corbiculate legs Ex- Alllegs of honeybee Fore legs (Eye brush, Antenna cleaner, Pollen brush) Middle legs (Pollen brush, Tibial spur) Hind legs (Pollen basket, pollen packer, pollen comb) @Bhubanananda Adhikari 12. Foragial (Food collecting) leg
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  Corbiculate legs Ex- Alllegs of honeybee Fore legs (Eye brush, Antenna cleaner, Pollen brush) Middle legs (Pollen brush, Tibial spur) Hind legs (Pollen basket, pollen packer, pollen comb) @Bhubanananda Adhikari 12. Foragial (Food collecting) leg
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  Thank You…