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Unit2 Locomotory organs.pptx

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namrathaparthasarath

The document discusses the locomotory organs (legs and wings) of insects. It describes the basic body plan of insects, which consists of 3 main body regions - head, thorax, and abdomen. The thorax contains 3 segments that each bear a pair of legs. The legs are typically segmented into 5 parts - coxa, trochanter, femur, tibia, and tarsus. The document outlines different types of leg modifications including saltatorial (jumping), raptorial (seizing), fossorial (digging), cursorial (running), and natatorial (swimming) legs. Each modification is adapted to specific insect behaviors and environments.

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LOCOMOTORY ORGANS (LEGS & WINGS) Leg of a Typical Insect & Leg Modifications
Insects - 3 major body regions: head, thorax, and abdomen .  Head - 5 to 7 fused segments (bears the eyes, antennae, and mouthparts).  Thorax - three segments (pro-, meso-, and metathorax).  Each of these segments - bears one pair of legs.  If wings are present - found on the meso- and metathorax only.  Appendages used for movement are also attached to the thorax.  The top of the prothorax is called the pronotum.  Abdomen - 11 or fewer segments that generally do not bear any appendages (except for segments near the rear which may have appendages associated with reproduction). OVERALL BODY PLAN
 Typical insect: 3 pairs of legs (Segmented type)  Position - Ventral surface of the thoracic segment (Pro-, meso-, and metathoracic regions)  Function :Primary organs of walking and running, but according to the habit and habitat, they are modified for various purposes.  Each leg contains- 5 segments i) Coxa ii) Trochanter iii) Femur iv) Tibia v) Tarsus  Pretarsus- typically represented by complex set of claws. TYPICAL INSECT LEG
i) Coxa: First or proximal or basal leg segment. It is freely movable and attached to the thoracic segment. ii) Trochanter: Second segement, small and single segmented except dragonfly and damselfly – 2 segmented (called Trochantelus) articulates with Coxa but usually attached to Femur. iii) Femur: Largest or stoutest and most powerful part of the leg Closely attached to Trochanter iv) Tibia: Long and slender part of the leg. Downward projecting spines are present (Func- Climbing and Footing). v) Tarsus: 5th segment sub segmented- 2-5 segments called Tarsomeres Pretarsus: 6th or last segment, pair of terminal curved structures claws (ungues). Lobe-like or adhesive pad structure in between the claws called Arolium. Pair of adhesive pads- pulvilli. Large bristle or lobe b/w claws- Empodium SEGMENTS OF TYPICAL LEG
MODIFICATIONS OF LEG i) Saltatorial -- jumping ii) Raptorial -- seizing iii) Fossorial -- digging iv)Natatorial -- swimming v) Cursorial – running While the legs are normally adapted for walking many insects have them modified for variety of functions. They are: i) Saltatorial/jumping Hind legs adapted for jumping. i) Work well for jumping because they (enlarged legs filled with bulky, strong muscles). iii) jump, propelling forward very long distances very quickly. These legs are characterized by an elongated femur and tibia. The femur is greatly enlarged giving articulation for large muscles of tibia which are used in jumping and leaping. Eg: Grasshoppers, crickets and katydids (order Orthoptera).
Raptorial legs/Seizing type : Modified for grasping (catching prey). • Modified from Saltatorial legs Eg: Mantids (order Mantodea), ambush bugs, giant water bugs and water scorpions (order Hemiptera). • hunting legs, the kinds of legs you see on predatory insects. • these legs are usually at the front of the insect and are used to grab and hold prey while they eat. • Coxa of foreleg is more elongated whereas the trochanter is small. Tibia is spinous and fits along the femur.
• Swiftly moving insects such as roaches and tiger beetles. • Cursorial legs tend to be long and narrow and are designed so that the insect can move very quickly. • Things with this type of leg are often hard to catch – or hard to step on if you’re dealing with roaches Eg: Ants,wasps, Cockroach etc. Cursorial/Running type: • differentiated by the tarsus which is comparatively longer and touches the ground while running. • Similar to walking legs.
Ambulatory/ walking type Similar to cursorial type. Femur and tibia are long. Legs are well developed similar in form. Eg:cockroach, leaf beetles. Natatorial (Swimming leg): e.g. Hind legs of water bug or water Beetle, Femur, tibia and first four tarsomeres are all broad and flattened. Their edges are provided with flattened setae. The hind legs serve as oars.
Fossorial (Digging leg): e.g. Fore legs of male cricket. Femur is shout. Tibia is short and shout and bears distally two or three strongly printed tines. The first two segments of tarsus are also produced into strong tines.
Scansorial (Clining leg): e.g. All three pairs of legs of head louse. Tibia is stout The tarsus is single segmented. There is a single large claw that usually forms an efficient mechanism for hanging on to the hairs of host.

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Unit2 Locomotory organs.pptx

  • 1. LOCOMOTORY ORGANS (LEGS & WINGS) Leg of a Typical Insect & Leg Modifications
  • 2. Insects - 3 major body regions: head, thorax, and abdomen .  Head - 5 to 7 fused segments (bears the eyes, antennae, and mouthparts).  Thorax - three segments (pro-, meso-, and metathorax).  Each of these segments - bears one pair of legs.  If wings are present - found on the meso- and metathorax only.  Appendages used for movement are also attached to the thorax.  The top of the prothorax is called the pronotum.  Abdomen - 11 or fewer segments that generally do not bear any appendages (except for segments near the rear which may have appendages associated with reproduction). OVERALL BODY PLAN
  • 3.  Typical insect: 3 pairs of legs (Segmented type)  Position - Ventral surface of the thoracic segment (Pro-, meso-, and metathoracic regions)  Function :Primary organs of walking and running, but according to the habit and habitat, they are modified for various purposes.  Each leg contains- 5 segments i) Coxa ii) Trochanter iii) Femur iv) Tibia v) Tarsus  Pretarsus- typically represented by complex set of claws. TYPICAL INSECT LEG
  • 4. i) Coxa: First or proximal or basal leg segment. It is freely movable and attached to the thoracic segment. ii) Trochanter: Second segement, small and single segmented except dragonfly and damselfly – 2 segmented (called Trochantelus) articulates with Coxa but usually attached to Femur. iii) Femur: Largest or stoutest and most powerful part of the leg Closely attached to Trochanter iv) Tibia: Long and slender part of the leg. Downward projecting spines are present (Func- Climbing and Footing). v) Tarsus: 5th segment sub segmented- 2-5 segments called Tarsomeres Pretarsus: 6th or last segment, pair of terminal curved structures claws (ungues). Lobe-like or adhesive pad structure in between the claws called Arolium. Pair of adhesive pads- pulvilli. Large bristle or lobe b/w claws- Empodium SEGMENTS OF TYPICAL LEG
  • 5. MODIFICATIONS OF LEG i) Saltatorial -- jumping ii) Raptorial -- seizing iii) Fossorial -- digging iv)Natatorial -- swimming v) Cursorial – running While the legs are normally adapted for walking many insects have them modified for variety of functions. They are: i) Saltatorial/jumping Hind legs adapted for jumping. i) Work well for jumping because they (enlarged legs filled with bulky, strong muscles). iii) jump, propelling forward very long distances very quickly. These legs are characterized by an elongated femur and tibia. The femur is greatly enlarged giving articulation for large muscles of tibia which are used in jumping and leaping. Eg: Grasshoppers, crickets and katydids (order Orthoptera).
  • 6. Raptorial legs/Seizing type : Modified for grasping (catching prey). • Modified from Saltatorial legs Eg: Mantids (order Mantodea), ambush bugs, giant water bugs and water scorpions (order Hemiptera). • hunting legs, the kinds of legs you see on predatory insects. • these legs are usually at the front of the insect and are used to grab and hold prey while they eat. • Coxa of foreleg is more elongated whereas the trochanter is small. Tibia is spinous and fits along the femur.
  • 7. • Swiftly moving insects such as roaches and tiger beetles. • Cursorial legs tend to be long and narrow and are designed so that the insect can move very quickly. • Things with this type of leg are often hard to catch – or hard to step on if you’re dealing with roaches Eg: Ants,wasps, Cockroach etc. Cursorial/Running type: • differentiated by the tarsus which is comparatively longer and touches the ground while running. • Similar to walking legs.
  • 8. Ambulatory/ walking type Similar to cursorial type. Femur and tibia are long. Legs are well developed similar in form. Eg:cockroach, leaf beetles. Natatorial (Swimming leg): e.g. Hind legs of water bug or water Beetle, Femur, tibia and first four tarsomeres are all broad and flattened. Their edges are provided with flattened setae. The hind legs serve as oars.
  • 9. Fossorial (Digging leg): e.g. Fore legs of male cricket. Femur is shout. Tibia is short and shout and bears distally two or three strongly printed tines. The first two segments of tarsus are also produced into strong tines.
  • 10. Scansorial (Clining leg): e.g. All three pairs of legs of head louse. Tibia is stout The tarsus is single segmented. There is a single large claw that usually forms an efficient mechanism for hanging on to the hairs of host.