Structural Organisation in Animals

Morphology and anatomy of cockroach

Morphology and Anatomy of Cockroach:

  • Cockroach: (Periplaneta americana) ⇒ American variety, (Blattella orientalis) ⇒ Indian type
  • Cockroach body is bilateral that belongs to the class insects of the phylum arthropoda. Which are considered to be the nocturnal Omnivores.
  • Entire body is covered by sclerites that is composed of jointed and chitinous exoskeleton, in which the dorsal plates are termed as Terga; Ventral plates : Tergum.
  • The body is divided into head, thorax and abdomen, where head is attached through neck to the thorax.
  • Abdomen consists of to segments, where in embryo exist 11 segments.
  • 10th segment ⇒ Anal cerci (both sex)
  • Male only posses a thread like anal styles that are absent in females.
  • Genital pouch → Females → 7 + 8 + 9 sternum.
  • Genital pouch is males lies at the hind limb of abdomen bounded by 9th and 10th terga together with sternum-9.
  • Tactile (Touch) receptors and olfactory receptors are antenna [longer in male]. Auditory receptor is fond in anal cerci. Antenna bears compound eyes.
  • Digestive system consists of alimentary canal that is divided into foregut, midgut → ventriculus, and hindgut. [Ileum → colon → Rectum →  Anus]
  • Foregut: Mouth cavity, Pharynx, Oesophgus, Crop and Gizzard.
  • Crop is a large thin walled, pear shaped sac which extends upto 4th abdominal segment.
  • Midgut is internally lined by glandular epithelium where in the opening, 6-8 short, narrow, hallow tubes called Hepatic Caecae (or) Enteric Caecae (lined by epithelium) and secretes digestive enzymes.
  • Malpighian tubules which functions for Excretory system are found at the junction of midgut and hindgut which are present 100 to 150 in numbers.
  • Cockroach exhibits open blood vascular system, where the blood vessels are poorly developed which open into Haemocael
  • Heart consists of funnel shaped, 13 chambers, where the hemolymph is circulated by alary muscles.
  • Cockroach bears a well developed respiratory system due to the presence of air tubes. (or) Trachea, then of tracheoles that posses fluids which comes in contact with the individual body cells.
  • Trached system carries oxygen directly to all the body cells. The main tracheal trunk opens to the exterior on body surface through 10 pairs of spiracles / stigmata that are segmented apertures.
  • Excretory system: Malpighian tubules, fad body cells, uricose glands and cuticle which regulates the amounts of nitrogenous material, water and in organic salts.
  • Nervous system: Segmentally arranged ganglia is 3 (Thorax), 6(abdomen)
  • Cockroach is dioecious (uni sexual). Male gonads are a pair of testes on their dorio - lateral side of 4th to 6th abdominal segments.
  • The paired vas a deferentia arise from testis, run posteriorly and downwards to open in to the ejaculatory duct which then opens into genital pouch through male genital pore.
  • Sperms are stored in seminal vesicles in the from of bundles called as spermatophore that are discharged during copulation.
  • Female gonads are a pair of yellow coloured ovaries which lie in 2nd-6th abdominal segments, which consists of 8, elongated, tapering and beaded tubes called ovarioles / ovarian tubules.
  • All the ovarioles of an ovary unite to form a short and wide lateral oviduct where the 2 lateral oviducts in their turn unite to form a very short median common oviduct which then opens into a large genital pouch by female genital pore on sternum 8.
  • A pair of accessory glands / collateral glands lie behind and above the pair of ovaries.
  • The male transfer spermatophores during copulation, directly into the genital pouch of female, where egg fertilize.
  • Fertilized eggs are surrounded by the secretions of collateral glands which hardness ootheca or egg case.
  • On an average, females produce 9-10 egg cases with each containing 14-16 eggs.

Part-1: View this video for the topic from 0:58 to 54:50

Part-2: View this video for the topic from 0:45 to 37:35

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