Cockroach — Core Principles
Core Principles
Cockroaches are common, nocturnal, omnivorous insects belonging to Phylum Arthropoda, Class Insecta. Their body is distinctly divided into head, thorax, and abdomen, covered by a hard chitinous exoskeleton.
The head bears antennae, compound eyes, and chewing mouthparts. The thorax has three pairs of legs and two pairs of wings (tegmina and hindwings). The abdomen shows sexual dimorphism, with males having anal styles and females possessing a boat-shaped 7th sternum forming a brood pouch.
Internally, they have an open circulatory system with a dorsal, tubular, 13-chambered heart. Respiration occurs via a tracheal system with spiracles. Excretion is handled by Malpighian tubules, making them uricotelic.
The nervous system is ventral, with ganglia. Reproduction involves separate sexes, with females laying eggs in protective oothecae. They undergo incomplete metamorphosis (egg, nymph, adult stages).
Important Differences
vs Earthworm
| Aspect | This Topic | Earthworm |
|---|---|---|
| Phylum | Arthropoda | Annelida |
| Body Segmentation | Head, Thorax, Abdomen (distinct) | Metamerically segmented (similar segments) |
| Exoskeleton | Chitinous exoskeleton present | Absent (moist cuticle) |
| Circulatory System | Open type (hemocoel, dorsal heart) | Closed type (blood vessels, aortic arches) |
| Respiratory System | Tracheal system (spiracles, tracheae) | Cutaneous respiration (through moist skin) |
| Excretory Organ | Malpighian tubules | Nephridia |
| Nervous System | Ventral nerve cord with ganglia | Ventral nerve cord with ganglia |
| Metamorphosis | Incomplete (hemimetabolous) | Direct development (no metamorphosis) |
| Locomotion | Jointed legs, wings (for flight) | Setae and muscular contractions |