Introduction

Why Periplaneta americana is used as a type study

Periplaneta americana, the American cockroach, is studied as a representative of the phylum Arthropoda (class Insecta, order Blattodea) because it is large-bodied, easy to collect, hardy, and shows every hallmark arthropod feature clearly — a chitinous jointed exoskeleton, a segmented body organised into head, thorax and abdomen, jointed paired appendages, and an open (haemocoelic) circulatory system. It is a cosmopolitan pest, meaning it is found worldwide in human dwellings, drains, kitchens, godowns and sewers, thriving as a nocturnal scavenger on almost any organic matter. Its wide availability and uniform body plan make it convenient for a detailed organ-system study in the laboratory.