Class insecta
- 3. CLASSIFICATION • Kingdom : Animalia • Phylum : Arthropoda • Subphylum : Hexapoda • Class : Insecta
- 4. General characters of class insecta • These are tracheated arthropods • It possesses 3 pairs of jointed legs • Body is segmented • Insect body is divided into 3 regions • Head • Thorax • Abdomen • It possesses a pair of compound eyes & antennae • Two pair of wings are present in adult stage
- 5. Identification • One pair of antennae • Usually one pair of compound eyes ; Simple eyes (ocelli) present in many groups
- 6. • One of the most diverse group of animal on earth 1. Represent more than half of all known living organism 2. Found in almost all environments 3. Number of extant species of class insects : 6-10 million 4. Represent over 90% of differing life forms on earth
- 7. Representatives • Fleas, moths, flies, wasps, mosquitoes, grasshopper, beetles, cockroaches, termites, butterflies, ants • Are mostly solitary, but some insects (bees, ants termites) are social and live in large, well-organized colonies • Communication occurs in many different ways; males can sense pheromones of female moths over distances of many kilometers (moths), sounds to
- 8. Basic Anatomy • Chitinous (hard) exoskeleton, no bones or a skeleton • Three-part body, head, thorax, abdomen • Three pair of jointed legs • Compound eyes which contain several thousand lenses leading to larger field of vision • Two antenna
- 10. Basic Anatomy cont: • Cuticle : Outer layer, made up of epicutle (thin, waxy, water resistant, no chitin) • Three body part : 1. Head : pair of sensory antenna, pair of compound eyes, and if Preset, one to three simple eyes and three sets of modified appendages that form the mouth part 2. Thorax : six segmented legs which are used for several things such as running or swimming, and if present, two or four wings 3. Abdomen : consists of eleven segments, contains most of the digestive , respiratory, excretory and reproductive internal structure • Only invertebrates who can fly, which is very important for their success: muscles are connected to exoskeleton and are able to contract multiple times for each nerve impulse
- 12. Nervous system • Brain and ventral nerve cord • Cells that detect and transmit sensations of pain (nociceotors), but not proven that insectscfeel pain consciously
- 14. Respiration and circulation • Insects do not have lungs! They breath passively through their “ spiracles” (openings in the sigde of their cuticle) . Oxygen is delivered directly via trachea ( series of smaller and smaller pipes) to the tissues that need it • Since diffusion of gases is only effective over small distances, insects are relatively small • Different patterns of gas exchange shown by different types of insects : continuous diffusive ventilation, discontinuous gas exchange , some insects have gills (extrect oxygen dissolved in water)
- 15. Reproduction and Development • Growth is constrained by inelastic exoskeleton • Mainly sexual reproduction between male and females • 4 different life stages (insects) eggs, larva, pupa, adult • Complete vs. Incomplete metamorphosis • Mosthatch from eggs , which are laid in a sheltered place or produced internallly Adult Larvae