Cockroach

  • The cockroach is a dioecious animal.
    • The cockroach is almost found everywhere and in all conditions.
    • Phylum: Arthropoda
    • Class: Insecta
    • Order: Dictyoptera
    • Chromosome number: 34
    • Size: 34-53mm
    • Runs at the speed of 130 m/s at 25-degree Celsius
    • Height: 1/4 to 3 inches (0.6 - 7.6 cm)
  • The body is divided into three parts.
    • Head
    • Thorax
    • Abdomen
  • Head (6), Thorax (3), Abdomen (11): 20 segments in the embryonic stage
  • Head (1), Thorax (3), Abdomen (10): 14 segments in adult
  • Sclerites in the cockroach are covered through the thin membrane called the articular membrane.
  • The dorsal side of the cockroach has tergites. [DT]
  • The ventral side of the cockroach has sternites. [VS]
  • The lateral side of the cockroach has a pleuron. [LP]
  • HEAD:
    • Triangular, 90 degrees, Hypognathous
    • The top part of the head is called the vertex.
    • Just below the vertex plates are present called frons.
    • On the lateral side, compound eyes are present which contain 2000 ommatidia.
    • There is also the presence of a fenestra/ ocellar spot which is a simple eye, and it is vestigial in the cockroaches.
    • Antennas have sensory receptors which help in sensing the environment.
    • Two flattened chitinous plates are present on the lateral side called Gena.
    • The clypeus is found on the anterior side, which is a mouth part covering
    • Mouth parts:
    • Labrum
      • Upper lip
      • Dorsal side
      • Broad, flattened, movable sclerite
    • Mandible
      • Lateral side
      • Jaw which comprises chitinous teeth
      • Biting and chewing
    • Maxilla
      • Lateral side
      • Helps in the pickup of food
      • Provides a platform
    • Hypopharynx
      • Tongue for cockroach
      • The salivary gland present at its base helps to secrete enzymes to digest.
    • Labium
      • Lower lip
      • Ventral side
  • THORAX:
  • It comprises three parts:
    • Prothorax
    • Mesothorax
    • Metathorax
  • The legs consist of 5 segments: [CTFTT]
    • Coxa
    • Trochanter
    • Femur
    • Tibia
    • Tarsus
  • The last segment contains claws that help to walk on rough surfaces.
  • Arolium helps to walk on smooth surfaces.
  • WINGS:
    • Fore wings/ Elytra/ Tegmina:
    • opaque
    • mesothorax
    • Hind wings:
    • transparent
    • metathorax
    • helps in flight at a time of danger
  • ABDOMEN:
    • 10 segments
    • 9 in male
    • 7 in female
    • Sexual dimorphism
    • 5th and 6th tergum: Stink gland (smell repels the enemies)
    • 10th tergum: Anal Cerci
    • Segmented (15 in number)
    • Sound receptors
    • Both males and females
    • 9th sternum: Anal style
    • Unsegmented
    • Helps in copulation
    • Only in males
    • 7th sternum: in females
    • Boat shaped
    • Gyno valvular plates
    • Non-segmented
    • Help in copulation
  • DIGESTIVE SYSTEM:
    • Alimentary canal: (3 parts)
    • Foregut
      • Ectodermal in origin
      • Moth to gizzard
      • Crop helps in the digestion of food.
      • Gizzard helps in grinding and crushing food with 6 cuticular teeth.
    • Midgut
      • Endodermal in origin
      • Hepatic caeca secrete the digestive juices
    • Hindgut
      • Malpighian Tubules (100-150)
      • Ileum
      • Colon
      • Rectum
    • Salivary glands:
    • Carbohydrate digesting enzymes
  • RESPIRATORY SYSTEM:
    • Respiratory unit: Respiratory tubules or Tracheal system
    • Spiracles are the network that heads out of the body
    • 10 pairs of spiracles
    • 2 pairs in the thorax
    • 8 pairs in the abdomen
    • Each spiracle opens into the atrium
    • The last ends of the trachea are called tracheoles
    • Tergo-Sternal muscles help in breathing
    • Both inspiration (inhalation) and expiration (exhalation) take place
    • The exchange of gases happens by simple diffusion
  • BLOOD VASCULAR SYSTEM:
    • Poor developed blood vessels.
    • Open-type blood circulation.
    • The organs are dipped in the hemocoel.
    • Hemocoel consists of colorless plasma and haematocytes.
    • 13- chambered heart
    • Dorsal and Tubular
    • at the end there is a structure called pulsatory ampulla
    • Nephrocytes help in blood circulation
    • 12 pairs of alary muscles also help in blood circulation.
  • EXCRETORY SYSTEM:
    • Main organ: Malpighian tubules
    • Rectal papillae: 6 in number
    • Number: 100-150
    • Uric Acid (excretory substance)
    • It helps in the removal of excretory substances
    • Fat bodies
    • Nephrocytes
    • Uricose glands (only present in males)