What is the Morphology of Cockroaches?
Cockroaches belong to the class Insecta of phylum Arthropoda. The scientific name of the cockroach is Periplaneta americana.
Cockroaches are 34-53mm long with wings that extend beyond the tip of the abdomen in males.
The body of the cockroach is segmented, bilaterally symmetrical, and triploblastic with the organ-level organization. The entire body is covered with a hard chitinous exoskeleton. In each segment of the body, the exoskeleton has hardened plates called sclerites (tergites dorsally and sternites ventrally) which are joined to each other by a thin, flexible membrane known as an arthrodial membrane.
The body of the cockroach is divided into three major segments – head, thorax, and abdomen. The head is triangular in shape and is fused together by six segments, thus showing the mobility and flexibility of the neck. The head comprises a pair of compound eyes and a pair of long, thread-like antennae arising from the membrane sockets present in the front of the eyes.
The antennae have sensory receptors used for sensing food, danger, and stress environments. Appendages that can be used for chewing and biting are present in the anterior part of the head, thus forming the mouth. The mouthparts comprise a labrum (upper lip), a pair of mandibles, a pair of maxillae, and a labium (lower lip). The mouthparts enclose a cavity within which the median flexible lobe, called the hypopharynx is found. It serves the purpose of a tongue.
A. Parts of head region B. Mouthparts
The thorax region consists of three parts – prothorax, mesothorax, and metathorax. The prothorax region extends into a short neck which connects the head and the prothorax region. Each thoracic region bears a pair of legs.
Two pairs of wings are present – the forewings/tegmina arising from the mesothorax region and the hind wings arising from the metathorax region.
The forewings are opaque dark and leathery, covering the hind wings when the body is at rest, whereas the hindwings are transparent, and membranous and are required for flying.
In both males and females, the abdomen region is made up of 10 short segments. In males, the genital pouch lies in the hind end of the abdomen dorsally bounded by the 9th and 10th terga and ventrally by the 9th sternum.
The male genital pouch consists of the ventral male genital pore, dorsal anus, and gonapophysis. Males bear short anal styles, which is absent in females. For the females, the 7th sternum is boat-shaped, which joins along with the 8th and 9th sternum to form a brood/genital pouch.
This female genital pouch consists of female gonophores, spermathecal pores, and collateral glands. A pair of joint filamentous structures called anal cerci is present in the 19th segment of both sexes.