Morphology of Cockroach (Periplaneta americana)

This set of vocabulary flashcards covers the morphology of the cockroach, specifically focusing on body segmentation, the exoskeleton structure, and detailed anatomy of the head.

Periplaneta americana

The scientific name of the cockroach species described in the lecture notes.

Adult Body Segmentation

The body is divided into three regions: Head ($1$ segment), Thorax ($3$ segments), and Abdomen ($10$ segments), totaling $14$ segments.

Embryonic Body Segmentation

The body structure in the embryo stage consists of Head ($6$ segments), Thorax ($3$ segments), and Abdomen ($11$ segments), totaling $20$ segments.

Sclerites

Hard chitinous plates that make up the exoskeleton of each segment; they are brown in colour.

Articular Membrane

A thin and flexible membrane, also called the arthrodial membrane, that joins the sclerites to each other.

Tergum

The name for the sclerites located on the dorsal side of the body; also referred to as tergite.

Sternum

The name for the sclerites located on the ventral side of the body; also referred to as sternite.

Pleurons

The name for the sclerites located on the lateral sides of the body; also referred to as pleurites.

Hypognathus

A term describing the orientation of the triangular head, which lies anteriorly at right angles ($90^{\circ}$) to the longitudinal body axis.

Vertex

The top part of the cockroach's head.

Occiput

A chitin plate present on the vertex of the head.

Ommatidia

The units that make up each of the two compound eyes; there are approximately $2000$ units per eye.

Fenestra

A small light-coloured spot, also called the ocellar spot, located on the dorsal surface close to each eye; it is a vestigial simple eye in cockroaches.

Antennae

A pair of thread-like, long, filamentous, unbranched, and free-moving sensors that arise from membranous sockets; they monitor the environment for touch, temperature, and vibration.

Frons

A big chitin plate situated below the vertex, also known as the forehead.

Gena

Two long flattened chitin plates situated on the lateral sides of the head, commonly referred to as the "cheek".