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External Anatomy III Lecture 12. Insects have evolved for more than 350 million years resulting in: Diverse biology & ecology Diverse morphology. Modification of abdomen. Moth. Ichneumon wasp. Katydid. Modification of legs. digging. grasping. grooming. pollen collecting. raptorial.
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Insects have evolved for more than 350 million years resulting in: • Diverse biology & ecology • Diverse morphology
Modification of abdomen Moth Ichneumon wasp Katydid
Modification of legs digging grasping grooming pollen collecting raptorial
Modification of wings elytron tegmen hemelytron haltere
Modification of mouthparts Butterfly Mosquito Honey bee
Modification of antennae Moniliform Clavate Filiform Serrate Pectinate Flabellate Plumose Aristate Geniculate
Insect Locomotion • Walking • Jumping • Flying
Walking: • Protraction – complete movement forwards of the whole limb relative to its articulation with the body • Retraction – the backward movement of the leg relative to its articulation between the time the foot is placed on the ground and the time it is raised • Tripod movement – one tripod (fore and hind legs on one side and mid leg of the opposite side) protracts while the other tripod retracts • Romaleaexample
Jumping: • Rapid release of energy stored in the muscle and in the cuticle • Hind leg– Orthoptera, Siphonaptera, Homoptera and some beetles • Modified abdominal appendages (furca) – Collembola • Thoracic arch – click beetles
http://whyfiles.org/2013/got-gears-lets-leap-says-the-leafhopper/http://whyfiles.org/2013/got-gears-lets-leap-says-the-leafhopper/
Flying: Direct flight system - flight muscle directly connected to wings - upward stroke achieved by contraction of muscles attached to the wing base inside the pivotal point - downward stroke achieved by contraction of muscles attached to the wing base outside the pivotal point contraction - Odonata
Flying: Indirect flight system - no muscle-to-wing connection - wings stroke due to deformation of thorax - upward stroke achieved by contraction of dorso-ventral muscle which depresses tergum - downward stroke achieved by contraction of dorsal longitudinal muscle which deforms the thorax and lifts tergum - Most insects
Flying: Indirect flight system - no muscle-to-wing connection - wings stroke due to deformation of thorax - upward stroke achieved by contraction of dorso-ventral muscle which depresses tergum - downward stroke achieved by contraction of dorsal longitudinal muscle which deforms the thorax and lifts tergum - Most insects
Wing beat frequency: • Synchronous muscle – contacts once per nerve impulse • Asynchronous muscle – contracts many times per nerve impulse
Keeping wings together for flight (wing coupling) Mecoptera Lepidoptera Lepidoptera Lepidoptera Hymenoptera hamuli
Haltere: • Modified hind wings of Diptera • Sense organ concerned with the maintenance of stability in flight