Structural Organisation In Animals (NEET)

Scientific classification of the common cockroach

Periplaneta americana; Phylum Arthropoda, Class Insecta.

Arthrodial membrane

A thin, flexible articular membrane that joins the hardened chitinous plates (sclerites) of the exoskeleton in cockroaches.

Components of cockroach mouthparts

Labrum (upper lip), a pair of mandibles, a pair of maxillae, labium (lower lip), and hypopharynx (flexible lobe serving as a tongue).

Tegmina

Opaque, dark, leathery forewings arising from the mesothorax that cover the hindwings when at rest and are not used in flight.

Morphological structure present only in male cockroaches

Anal styles (caudal styles), which are a pair of short, unjointed thread-like structures on the $9^{\text{th}}$ sternum.

Proventriculus (gizzard) in cockroach

A foregut structure featuring an outer layer of thick circular muscles and an inner cuticle forming six chitinous teeth used for grinding food.

Hepatic (gastric) caecae

A ring of $6\text{--}8$ blind tubules at the junction of the foregut and midgut that secretes digestive juices.

Malpighian tubules in cockroach

A ring of $100\text{--}150$ yellow, thin filamentous tubules at the junction of the midgut and hindgut that absorb nitrogenous wastes from haemolymph and convert them to uric acid.

Mosaic vision

Vision produced by approximately $2000$ hexagonal ommatidia per compound eye, characterized by higher sensitivity and lower resolution (nocturnal vision).

Spermatophores

Bundles of sperms glued together and stored in the seminal vesicles of male cockroaches, discharged during copulation.

Paurometabolous development

Development through nymphal stages resembling adults, where nymphs undergo about $13$ moults to reach the adult form.