Sense Organs of Cockroach

Sense Organs of Cockroach

Receptor cells are present on general body surface.

Proprioreceptor: They are of hearing or receiving sound vibrations. Auditory receptors are present on antenna and anal cerci.

Thigmoreceptors: They are receptors of touch. Thigmoreceptors are present on body, antenna, maxillary palps and legs.

Olfactory receptors: They receive various smells. Olfactory receptors are present on antenna and palps.

Gustatory receptors: They are for sense of taste. Gustatory receptors are present on maxilla and labial palps.

Eyes

1. Cockroach has compound eyes. Each compound eye is formed of a number of ommatidia. Each ommatidium has a biconvex lens or cornea. Below the lens there are corneagen cells which secrete the lens.
    
2. Below the corneagen cells is a transparent crystalline cone surrounded by four vitrellae or cone cells. The vitrellae secrete the crystaline cone. All this form the focusing or dioptrical region.
    
3. Below the cone there is a refractive body the Rhabdome, surrounded by seven retinular cells. Each ommatidia is isolated from the other by iris pigment sheath.
    
4. The image formed in apposition or mosaic vision composed of as many separate but adjacent images as there are ommatidia. In mosaic vision images are sharp but separate and the eye can use only bright light.
   
   In cockroach vision is mosaic and apposition image is formed (although cockroach in nocturnal). If pigmented iris sheath is removed from the compound eye of insects, only superposition image will formed.