2. External Morphology of an Insect

External Morphology of an Insect








EXTERNAL MORPHOLOGY OF AN INSECT
 Eg. Grass hopper

The insect body is grouped into three distinct regions or tagmata (Singular: Tagma) namely head, thorax and abdomen. This segmentation of the body into functional unit is called tagmosis. 
Head
ü This anterior tagma is composed of five sclerites namely vertex, frons, clypeus, gena and occiput that are joined by “sutures”.
ü  The head capsule is called as “cranium” and strengthened by a set of invagination of cuticle called tentorium.
ü  Head is a centre for sensing and feeding.
ü  Head consists of a pair of antenna, a pair of compound eyes, three simple eyes and mouth parts.  Head is connected to the thorax through the neck or cervix. 



Thorax:
ü  This is the middle tagma which is divided into three segments namely prothorax, mesothorax and metathorax.
ü  Meso- and meta-thorax bears two pairs of wings (forewing and hind wing) and are called pterothorax.
ü  Each segment consists of a pair of legs namely fore legs (prothorax) middle legs (mesothorax) and hind legs (metathorax).
ü  It is the centre for locomotion. 
Abdomen:
ü  It is the largest, eleven segmented (Uromers) posterior tagma.
ü  Eleventh segment, being reduced and divided into three lobes namely a dorsal epiproct and a pair of paraproct that surround the anus.
ü  The terminal segments may bear a pair of cerci.
ü  Spiracles are present on each side of the first eight abdominal segments.
ü  8th and 9th segments bear the genital structure , hence are known as genital segments. Female egg laying organ (ovipositor) is present in 8th and 9th segment while male genitalia present in 9th segment.
Abdomen is the centre for reproduction.


Comments

Post a Comment

Popular posts from this blog

Collection and preservation of insects

Image
https://www.youtube.com/watch?v=qc-TvXmKQJ0 https://www.youtube.com/watch?v=4k7I4cdKnMI COLLECTION,KILLING AND PRESERVATION OF INSECTS The five steps in the collection, Killing and preservation of insects are 1.        Collection 2.       Killing 3.       Preservation 4.       Storage and 5.       Display I.   Collection Why? To study about the insect. When? Early morning and late evening. Where? ü   In the air ü   In fresh or brackish water ü   On the foliage or stems of trees and Shrubs ü   On the ground or near the roots of plants ü   Internally in plants, plant products, seeds, and fruit ü     among debris ü   In the nests or habitations of animals and man ü   In the soil ü     On or in other insects or animals How?   Various methods and equipments have been used to colle
Read more

Insect wing, Modifications and Copulation

Image
INSECT WING, ITS REGIONS, VENATION AND MODIFICATIONS v   Insects have a pair of wings in thorax. v   Wings are located dorso-laterally between the nota and pleura of the meso- and meta-thoracic segments. v   The wing bearing segments (meso- & metathorax) are called pterothorax. Wing venation             The arrangement of veins in the insect wing is called wing venation . Each wing consists of a thin membrane supported by a system of thickened tubular veins. The membranous area between the veins is called cell . The veins strengthen the wings and give rigidity besides aiding blood circulation. Insect wing consists of longitudinal (principal) veins , which runs along the length, and cross veins , which connects the longitudinal veins. A hypothetical wing will have the veins as follows: Longitudinal veins/ principal veins Cross veins Costa (C) Sub-cost
Read more

Endopterygota: Coleoptera & Neuroptera

Image
https://www.youtube.com/watch?v=28YOYPK4qqE https://www.youtube.com/watch?v=0zECnVZyYDI&t=48s Endopterygota (Holometabola) Order COLEOPTERA Beetles             Coleo – Stony             Ptera – Wings •         Largest order in animal kingdom comprising 25% of all animal species •         40% of known insects are beetles •         Predatory, phytophagous, saprophagous 1. Chewing mouth parts, well developed mandibles 2. Fore wings – elytra, not used in for flying, hind wings-membranous, folded beneath elytra 3. Larval stages called as grubs 4. In most species, abdominal tip not covered by elytra and is called pygidium Sub-order: Adephaga 1. Family: Carabidae             Ground beetles •         Shiny, flat, black beetles with slender, long legs •         Antennae arise laterally on the sides
Read more