AP Inter 1st Year Zoology Notes Chapter 7 Type Study of Periplaneta Americana

Students can go through AP Inter 1st Year Zoology Notes 7th Lesson Type Study of Periplaneta Americana will help students in revising the entire concepts quickly.

AP Inter 1st Year Zoology Notes 7th Lesson Type Study of Periplaneta Americana

→ There are two species of cockroaches prevalent in India. Periplanata americana and Blatta orientalis.

→ Cockroaches are nocturnal animals commonly called as Kitchen pest.

→ Cockroaches are cursorial animals and are omnivores.

→ The thickened exoskeleton chitinous plates of cockroach are called sclerites.

→ Body wall is made up of cuticle, epidermis and basement membrane.

→ Cockroach body segmentation is called ‘Heteronomous segmentation’.

→ Jointed legs are present hence the name is Arthropoda.

→ Body cavity is haemocoel. Open type of blood vascular system is present.

→ Tracheal respiratory organs and malpighian tubules also minimise the loss of water.

→ Body of cockroach has 21 segments in embryonic stage. But in adult stage it has only 20 segments.

AP Inter 1st Year Zoology Notes Chapter 7 Type Study of Periplaneta Americana

→ Head is covered by 6 sclerites; contain sense organs and biting and chewing mouth parts and sense organs like compound eyes, antennae and fenestrae.

→ As the jaws are directed downwards, the head is described as hypognathous head.

→ Pronotum is the largest sclerites in the body.

→ Anal styles are present only in male cockroach.

→ Thorax is dorsally covered by 3 sclerites called nota. Thorax has a pair of wings, three pairs of jointed legs and two pairs of spiracles.

→ Abdomen has 10 terga and nine sterna. A pair of paraprocts is present. Below the tenth tergum, between which, anus is present.

→ Abdomen also has chitinous gonoapophyses.

→ Body wall of cockroach is formed by an outer cuticle, epidermis and dermis.

→ Cuticle is formed by an outer thin non-chitinous epicuticle, middle rigid layer of exocuticle and inner endocuticle.

→ Epidermis is formed by columnar gland cells, trichogen cells, tormogen cells and oenocytes.

→ The endoskeleton is in the form of invagination of scelrotised cuticje. These are called apodemes.

→ In the head the endoskeletal parts are fused to form tentorium.

→ The abdominal terga of 5th and 6th segments have stink glands and their secretions have an offensive odour.

→ Cockroach is a cursorial insect but it can fly short distance when emergency time.

→ Cockroach is an omnivorous insect that feeds on wood, paper, leather etc.

AP Inter 1st Year Zoology Notes Chapter 7 Type Study of Periplaneta Americana

→ In cockroach the alimentary canal is divisible into Stomodaeum, Mesenteron and Proctodaeum.

→ In front of the mouth a pre-oral cavity is present which is divided into an anterior cibarium and posterior salivarium.

→ Alimentary canal consists of pharynx, oesophagus, crop, gizzard, mesenteron, ileum, colon and rectum.

→ Malpighian tubules are present, acts as excretory in function.

→ Rectum has rectal papillae, which help in absorption of water from the faecal matter where water is absorbed and then egested in the form of pellets.

→ Cockroach has a pair of salivary glands. They secrete amylase.

→ Gland cells of midgut secrete maltase, invertase, protease and lipase.

→ The digested food is absorbed in the posterior region of ventriculus.

→ The undigested food reaches the rectum.

→ In cockroach the respiratory system is described as tracheal system.

→ The tracheal system communits to exterior through 10 pairs of spiracles.

→ Each spiracle is encircled by a chitinous supporting ring called peritreme.

→ Spiracles open into the atria.

AP Inter 1st Year Zoology Notes Chapter 7 Type Study of Periplaneta Americana

→ Tracheal trunks are connected by commissural trunks.

→ These trunks give out branches to different organs and end in tracheole cells.

→ Each tracheole cell has many intracellular tubular branches called tracheoles.

→ Innermost cuticular lining of the tracheae is called intima.

→ Intima forms spiral thickenings called tenidia. They keep the trachea always open.

→ Inspiration is effected by the relaxation of dorso ventral muscles and contraction of ventral longitudinal muscles.

→ Expiration is effected by the contraction of dorsoventral muscles and relaxation of ventral longitudinal muscles.

→ Cockroach exhibits discontinuous ventilation.

→ Central nervous system of cockroach consists of a nerve ring and double ventral nerve cord.

→ The nerve ring formed by the brain or supra oesophageal ganglia, sub oesophageal ganglia and circum oesophageal connectives.

→ Supra oesophageal ganglia are main sensory centers and sub oesophageal ganglia are the main motor centres.

→ Ventral nerve cord has nine ganglia.

→ Ventral nerve cord extends upto 7th abdominal ganglion only.

→ 5th abdominal segment has no ganglion.

AP Inter 1st Year Zoology Notes Chapter 7 Type Study of Periplaneta Americana

→ Autonomous nervous system is the stomata gastric nervous system.

→ It contains four ganglia. They are frontal ganglion, hypo cerebral ganglion, visceral ganglion and pro-ventricular ganglion.

→ It controls the visceral organs particularly muscles of gut and heart.

→ Sense organs of cockroach includes sensiila, compound eyes, ocelli etc.

→ Sensilla are the units of cuticular receptors.

→ Compound eyes are formed by many functional units-called ommatidia.

→ Ocelli represent the simple eyes and are located at the bases of antennae.
They are sensitive to light intensity. They will not form images.

→ Abdomen : Third or posterior division (tagma) of an insect.

→ Antenna : A sensitive feeler from the animals head; tactile and olfactory in function.

→ Appendage : A movable projecting part of the body; mouth parts are modified appendages.

→ Arolium : A soft hairy pad between claws in the leg of cockroach.

→ Arthropod : A phylum of segmented invertebrates with jointed legs.

→ Biramous : Possessing two branches, e.g. : the exopodite and endopodite.

→ Blastula : Embryonic stage with blastocoel, which is also called the ‘primary body cavity’.

→ Cephalic : Relating or to the head.

→ Cervix : Neck.

AP Inter 1st Year Zoology Notes Chapter 7 Type Study of Periplaneta Americana

→ Chitin : A polysaccharide-protein complex; a horny substance.

→ Copulation : Sexual process/union for the transfer of sperm from one to another of mating partner.

→ Cursorial : Swift runner.

→ Cuticle : External skeletal structure of the insect’s body; it has epicuticle, mesocuticle and endocuticle.

→ Dioecious : Species population in which male and female organs occur in separate individuals.

→ Dioptric region : The part that focuses light rays on to the inner part of an ommatidium.

→ Ecdysis : Shedding of the outer body layer (cuticle).

→ Germarium : Tapering anterior filament of an ovariole.

→ Haemocoel : The body cavity of an arthropod or a mollusk filled with haemolymph; derived from the blastocoels of the embryo; also called the ‘primary body cavity’.

→ Nervures : Tubular hollow network of the wing of a cockroach.

→ Ootheca : A hard purse like structure containing eggs in two rows.

→ Ovariole : A single tubule of an ovary containing developing eggs.

→ Paurometabolic : Gradual development / metamorphosis by the nymphal stages of certain insects.

→ Podomere : A segment of an arthropod leg.

→ Pulvillus : A soft hairy pad between claws.

AP Inter 1st Year Zoology Notes Chapter 7 Type Study of Periplaneta Americana

→ Sternum (plural : sterna) : A ventral sclerite of a body segment of insects such as a cockroach.

→ Tagma (plural : tagmata) : One of regions of the body of an insect; division of the body into different regions is called tagmatisation.

→ Tergum (plural : terga) : Dorsal sclerite of the body segment of an insect.

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