Thursday 1 February 2018

COCKROACH

Class- insecta
Phylum- arthropoda
Cockroaches are brown or black bodied 1/4 inches to 3 inches long animal and have antennae, head and legs.
They are nocturnal.
They are omnivorous.
They are vector of several disease.

MORPHOLOGY

-Body is divided into head, thorax and abdomen.
-Entire body is covered by hard chitinous exoskeleton.
-Exoskeleton has hardened plates called sclerits.
-Head is triangular in shape.
-Head is formed by fusion of 6 segments, hence it has great mobility in all direction.
-Head bears a pair of compound eye.
-A pair of antennae arise from membranous shockets lying in front of eyes.
-Antennae has sensory receptors.
-The mouth part consists of labrum(upper lip), a pair of mandibles,a pair of maxillae and a labium(lower lip)
-Hypopharynx acts as tongue.
-Thorax-protothorax-known as neck,connect head and thorax.
             mesothorax-first pair of wings arises.
             metathorax-second pair of wings arises.
       each segment of thorax bear a pair of walking legs.
-The abdomen of both male and feamle consist of 10 segments.

ANATOMY

-The alimentary canal is divided into foregut, midgut and hindgut.
-Mouth opens into pharynx, opens into oesophagus, opens into crop which finally opens into gizzard.
-Ring of 6-8 blind tubule called hepatic caecae secretes digestive juice.
-At the junction of midgut and hindgut 100-150 ring of malphigian tubules are present which help in excreation.
-Cockroach is uricotelic animal.
-Hindgut is differentiated into ileum, colon and rectum.
-Rectum opens into anus.
-Blood vascular system is of open type,vessels are poorly developed.
-Haemolymph is composed of colourless plasma and haemocytes.
-Heart is differentiated into funnel shaped chambers and ostia on either side.
-Respiratory system consist of network of trachea.
-Trachea opens through 10 pairs of holes called spiracles, which helps in diffusion of gas for respiration.

NERVOUS SYSTEM-
-Nervous system consist of fused segmentally arranged ganglia.
-3 ganglia lie in thorax and six in abdomen.
-Nervous system of cockroach spread throughout body a bit of  N.S. is in head and rest is situated along belly side(ventral part) of its body.
      Hence, it is easy to understand that  if it's head is cut off, it will still alive for a week.
-Sense organ are antennae,compound eye, maxillarypalps,labial palps and cerci.
-Compound eye are situated at dorsal surface of head.
-Each eye consists of 2000 hexagonal ommatidia.
-Ommatidia helps in receiving several images of same object having less resolution. It gives mosaic vision.

REPRODUCTION-
-Male and female body are separate.
-In male 4th- 6th segment of abdomen consists of a pair of a testes.
-Vas deferens attached to testes opens into ejaculatory duct through seminal vesical, which opens into gonopore.
-External genitalia of male is represented by gonapophysis.
-In female 2nd-6th segment of abdomen consists two large ovaries.
-Each ovary forms of 8 ovarioles(chain of developing ova)
-Ootheca-fertilized eggs are stored here.
-Female cockroach  produces 9-10 ootheca, each ootheca contains 14-16 eggs.
-Development is paurometabolous, means development through nymphal stage.

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