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COCKROACH

Updated: Oct 27, 2021

CLASSIFICATION

  • Kingdom- Animalia

  • Phylum- Arthropoda

  • Class- Insecta

  • Order- Blattodea

  • Family- Blattidae

  • Genus- Periplanetta, Blatta

  • Species- More than 4500 species of cockroaches


general points

  • Habitat- Warm, dark and damp places like kitchen, store houses, sewers.

  • Body size- Length- 0.6cm - 7.6cm; Periplanetta americana- 3.4cm- 5.3cm.

  • Body shape- Dorsoventrally flat.

  • Body color- Usually Brown or black; some species have yellow, red, green body color.

  • Body symmetry- Bilateral symmetry.

  • Habit- Nocturnal i.e. feeds at night time.

  • Exoskeleton- Made up of hard chitinous plates called Sclerites.

  • Nutrition- Omnivores/ Scavengers/ some species of cockroaches show Cannibalism.

  • Most common species of cockroaches are Periplanetta americana (American cockroach) and Blatta orientalis.

  • Cockroaches are considered as serious pests and are vector for several diseases.


morphology


Body is divided into 3 distinct regions- Head, Thorax and Abdomen.


1. head

  • Triangular in shape.

  • Made up of 6 chitinous plates called Cephalic sclerites in Embryo.

  • In adults, the cephalic sclerites are fused to form a single Head Capsule.

  • I Cephalic sclerite- Occiput- present at the top of head and is made up of 2 parts called Epi-cranial plates joined at Epi-cranial suture.

  • II Cephalic sclerite- Frons- present below the occiput on anterior part of the head.

  • III Cephalic sclerite- Clypeus- present just below the Frons on the anterior part.

  • IV Cephalic sclerite- Post-Occiput- present downward to the posterior part of Occiput.

  • V Cephalic sclerite- Gena- present on the lateral position.

  • VI Cephalic sclerite- Post-Gena- present inner to Gena.

  • Head also has mouth parts and several sense organs on it.

1.1 Mouth

  • Mouth is downward facing called Hypognathous mouth.

  • Mouth type is bitting and chewing type.

  • Made up of several parts- Labrum, Mandibles, Maxilla, Hypopharynx, Labium.

  • Labrum- also known as upper lip which hangs from Clypeus.

  • Mandible- a pair of Mandibles are present inner to Labrum and consists of grinding and incising regions for cutting the food.

  • Maxilla- a pair of Maxilla are present beneath the Mandible for mastication of food, helps in cleaning the antennae and also has Maxillary palp consisting of olfactory receptors.

  • Labium- also known as lower lip and is formed by fusion of two parts. A pair of Labial palp also arises from Labium which consist of sensory bristles attached to it.

1.2 sense organs


1.2.1 ANTENNAE

  • Paired.

  • Multi-segmented and each segment is called Podomere.

  • Long and filiform.

  • Arises from Antennal sockets.

  • Bears tactile, thermal and olfactory receptors to monitor the surroundings.

1.2.2 COMPOUND EYES

  • Paired

  • Black colored

  • Bean shaped

  • Dorsolaterally placed on top of the head

  • Made up of 2000 units called Ommatidia.

  • Produces mosaic vision

1.2.3 OCELLUS/ FENESTRAE

  • Round, pale.

  • Present inner and upper to each antennal sockets.

  • Vestigeal simple eyes.


2. THORAX

  • Divided into 3 segments:-

Prothorax

Mesothorax

Metathorax

  • Each segment of thorax is made up of 4 chitinous sclerites called dorsal Tergum, 2 lateral Pleura and ventral Sternum.

  • The Tergum of Prothorax called Protonum is extended to protect the neck and is the largest sclerite.

  • Each thoracic segment bears a pair of legs called Pro-legs, Meso-legs and Meta-legs arising from Prothorax, Mesothorax and Metathorax respectively.

  • 2 pair of wings called Forewings and Hindwings arises from Mesothorax and Metathorax respectively.

  • Forewings/ Mesothoracic wings- Thick, leathery, and dark in color. Not used for flight but protects and covers the Hindwings.

  • Hindwings/ Metathoracic wings- Thin, transparent, delicate and broad. Used for flight.


3. abdomen

  • Made up of 11 segments in embryo but reduced to 10 segments in adults.

  • Abdomen in broader than thorax and dorsoventrally flat.

  • A typical abdominal segment consist of dorsal Tergum, 2 lateral Pleura and ventral Sternum but the 10th segment lacks sternum.

  • In males, the 7th tergum covers the 8th tergum but all 9 sternum are visible in males.

  • In females, the 7th tergum covers the 8th and 9th tergum and the 7th sternum covers the 8th and 9th sternum.

  • Anal cercus- Long thick structures arising from 10th tergum which bears tactile and phonoreceptors. Present in both males and females.

  • Anal styles- Thin and small outgrowth arising from 9th sternum and bears tactile receptors. Anal styles are exclusive to males and are absent in females.

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