EXTERNAL MORPHOLOGY OF AN INSECT

        EXTERNAL MORPHOLOGY OF AN INSECT 

                          GRASSHOPPER

TAGMOSIS

               Segmentation of insect body into distinct regions or functional unit is called as tagmosis. 

TAGMA

               Insect body is differentiated into three distinct regions such as head, thorax and abdomen and each distinct region is called as tagma. 

The insect body consists of three tagma or three distinct region they are

               I.   Head

              II.   Thorax 

             III.   Abdomen

I. HEAD

         *  The first anterior segment of the insect body.     

         *  It's centre for sensing and feeding. 

         *  Head is attached to the thorax through neck or Cervix. 

         * Head capsule is sclerotized and the head capsule excluding appendages formed by the fusion of several sclerites is known as Cranium.

   Segments of the head

          The head is formed by the fusion of segments such as, 

              *  Preantennary segment

              *  Antennary segment

              *  Intercalary segment 

              *  Mandibular segment

              *  Maxillary segment 

              *  Labial segments

   Sclerites of head

       The head is covered by the hardened plates called sclerites. 

          i. Vertex: Summit of the head between compound eyes.

         ii. Frons: Facial area below the vertex and above clypeus.

        iii. Clypeus: Cranial area below the frons to which labrum is attached.

        iv. Gena: Lateral cranial area behind the compound eyes.

         v. Occiput : Cranial area between occipital an post occipital suture.

     Sutures of Head

       Sclerite plates are joined by soft sutures

          i. Epicranial suture: (Ecdysial line) Inverted `Y' shaped suture found medially on the top of

head, with a median suture (coronal suture) and lateral suture (frontal suture).

        ii. Epistomal suture: (Fronto clypeal suture) found between frons and clypeus.

       iii. Clypeo labral suture: Found between clypeus and labrum.

       iv. Post occipital suture: Groove bordering occipital foramen. Line indicating the fusion of

maxillary and labial segment.

       *  Endoskeleton of insect cuticle provides space for attachment of muscles of antenna and mouthparts, called as Tentorium.

       *  The head consists of

               A pair of compound eyes

               0-3 ocelli( simple eyes) 

               A pair of antenna 

               Mouth parts

FUNCTIONS OF HEAD

        i. Food ingestion

       ii. Sensory perception

      iii. Coordination of bodily activities

      iv. Protection of the coordinating centers

II. THORAX

              *  It's second and middle tagma of the insect body. 

              *  It is a centre for locomotion

              *  It has three segments namely

                      Prothorax

                      Mesothorax

                      Metathorax

              *  Meso and metathorax with wing are called as Pterothorax

              *  Thoracic appendages has three pairs of legs and two pairs of wings.

              *  Thorax is made up of three scleritic plates namely, 

         Dorsal body plate (Tergum or Nota)

                   Dorsal body plate of each thoracic segments are called as pronotum, mesonotum 

and metanotum. 

              Pronotum

                     This sclerite is undivided and Saddle shaped in grass hopper, Shield like in cockroach.

             Pterothoracic notum(mesonotum 

and metanotum) 

                   -  Have 3 transverse sutures 

                           I. Antecostal

                          II. Pre scutal

                         III. Scuto-scutellar

                  -   Have 5 tergites

                          I. Acrotergite

                         II. Prescutum

                        III. Scutum

                       IV.  Scutellum

                        V.  Post-scutellum

           Ventral body plate (Sterna)

                     *   Vental body plate of each thoracic segments are called as prosternum, mesosternum and metasternum. 

                     *   Thoracic sterna is made up of a segmental plate called Eusternun and a intersternite called Spinasternum.

                     *    Eusternum is made up of three sclerites viz., 

                               I. presternum

                              II. basisternum 

                             III. sternellum.

          Lateral plate (Pleura)

                    *   Lateral body wall of thoracic segment between notum and sternum.

                    *   Selerites of pleuron is called as pleurites and they fuse to form Pleural plate.                                *   Pleural plate is divided into anterior episternum and posterior epimeronFunctions of thorax: Mainly concerned with locomotion. by Pleural suture. 

                    *  Pterothoracic pleuron provides 

space for articulation of wing and leg. 

                    *  Two pairs of spiracles are present in the mesopleuron and metapleuron . 

FUNCTIONS OF THORAX

             Mainly concerned with locomotion.

 III. ABDOMEN

            *    It is the third and posterior tagma. 

            *   This tagma is made up of 9-11 Uromeres  (segments) and is highly flexible.

            *   It is a centre for metabolism and reproduction. 

            *   It is the longest soft body division and has 11 Telescopic segments. 

            *   Abdominal segments are interconnected by a membrane called conjunctiva. 

            *   An oval shaped auditory membrane, tympanum is present laterally on the either sides of the first abdominal segments. 

            *   Each abdominal segment is made up of only two sclerite namely dorsal body plate  (tergum) and ventral body plate (sternum).

             *  Eight pairs of spiracles are present in first eight segments. 

             *  Eight and ninth abdominal segments bears the female genital structure and ninth segment bears male genital structure. 

             *  The individual segments of abdomen is called as uromeres. 

             *   11th segment is reduced into lobes namely,

                         Dorsal epiproct

                         A pair of paraproct

              *  Cerci and anus lies between these two lobes. 

FUNCTIONS

             Concerned with reproduction and metabolism.

QUESTIONS TO PONDER

                1. Segmentation of insect body into distinct regions or functional unit is called________________.

                2. ______________ is the facial area below the vertex and above clypeus.

                3. Sclerite plates are joined by soft______________.

                4. Endoskeleton of insect cuticle provides space for attachment of muscles of antenna and mouthparts called________________.

                5. Meso and metathorax with wing are called______________.

                6. _______________ is mainly concerned with locomotion. 

                7. Abdomen is made up of __________ Uromeres (segments). 

                8. Abdominal segments are interconnected by a membrane called______________.

                9. An oval shaped auditory membrane, _______________ is present laterally on the either sides of the first abdominal segments

               10. Eight and ninth abdominal segments bears the __________________.

Hello, everybody 

Here is a YouTube link regarding this blog , which facilitate you to with extra information and easy understanding. ☺👍

👉👉external morphology of an insects