Question

Describe the head of a cockroach.

Answer 1

Cockroaches belong to the phylum arthropoda of kingdom animalia. They have jointed appendages, their exoskeleton made up of chitin. Around 90% animals out of total animals belong to this phylum. Parental care is not found in cockroaches. Cannibalism is found in cockroaches ie if food is not available, then their own species is eaten as food.

Complete answer:
Head of cockroach:
Hypognathous condition: that's bent downwards at an angle of 90 degree from the long axis of the body.
Sclerites of the top joined fully and formed a head capsule.
Top part of the head is called 'vertex' and on the vertex is a chitin plate present called 'occiput'.
On the lateral side of the head apex 1 pair of compound eyes present.
Each compound eye is made up of 2000 units called 'ommatidia'.
A small light coloured spot called fenestra or ocular another is located upon the dorsal surface close to each eye.In insects it functions as a photoreceptor organ. In cockroaches it is inactive and called 'vestigial simple eye'.
Lateral side of head apex bear of 1 pair of antennae. Main receptor of touch, temperature vibration in cockroach.
A big chitin plate situated below the vertex called 'front or foreheads.
Two long flattened chitin plates situated on the lateral side are called 'gena' or 'cheek'.
A big chitin Plate present within the anterior part of front is named 'clypeus', a movable chitin plate joined with the anterior part of 'clypeus' referred to as ' labrum 'or 'upper lip'.
A big pore situated in the ventricles part of the head is called ' occipital foramen'.
Occipital filaments surrounds by two pair of chitin plate:
Internal:- post occipital
External:- post Gena
A mouth situated in the anterior side of the head which is surrounded by many chitinous structures called 'mouth parts'.

Note:
Antennae of cockroaches are long, filiform, unbranched, each antenna extending forwards from an antenna socket located dorsal upon the head capsule near the compound eye of its side; these are free moving. The mouthparts of cockroaches are according to the food habit, these are of biting and chewing type,a cavity formed due to mouthparts called 'pretrial cavity' or 'cibarium'.