Morphology and Anatomy of Cockroach

What Is The Morphology And Anatomy Of A Cockroach?

The cockroach is a class of Insecta, phylum Arthropoda. Its body is divided into three distinct parts: head, thorax, and abdomen. Its entire body is covered with a hard, chitinous exoskeleton.

The Head Of A Cockroach

• The head is triangular in shape and lies at a right angle to the longitudinal body axis. It is formed by the fusion of six segments, and with a flexible neck, it is highly mobile in every direction.

• The head capsule bears a single pair of compound eyes, each eye consisting of many hexagonal ommatidia.

• A pair of thread-like antennae arise from membranous sockets in front of the eyes, and they bear sensory receptors that help in monitoring the environment.

• The anterior end of the head bears appendages forming a biting and chewing type of mouthparts, including a labrum (upper lip), a pair of mandibles and maxillae, and a labium (lower lip).

• A median flexible lobe, acting as a tongue (hypopharynx) lies within the cavity enclosed by the mouthparts.

The Thorax Of A Cockroach

• The thorax comprises three parts: prothorax, mesothorax and metathorax.

• The head is connected to the thorax by a short extension of the prothorax known as the neck.

• Each thoracic segment bears a pair of walking legs.

• The first pair of wings arises from the mesothorax and the second pair from the metathorax.

• The forewings, or mesothoracic, are called tegmina, which are opaque, dark, and leathery; at rest, they cover the hind wings.

• The hind wings are transparent and membrane-like and are used for flying.

Abdomen Of A Cockroach

• Abdomen In both males and females, the abdomen consists of 10 segments.

• In females, the 7th sternum is boat-shaped and, together with the 8th and 9th sterna, forms a brood or genital pouch whose anterior part contains the female gonopore, spermathecal pores and collateral glands.

• In males, the 9th sternum is boat-shaped and bears a pair of short, unjointed leg-like structures called anal styles.

Exoskeleton And Segmentation

• The entire body of the cockroach is covered by a hard, chitinous exoskeleton that protects and supports the internal organs.

• This exoskeleton is segmented, with a pair of generally similar appendages—legs, and wings—attaching to each segment.

Compound Eyes And Antennae

• Cockroaches have a pair of compound eyes with many hexagonal ommatidia.

• These eyes provide an enormous field of vision and allow the cockroach to detect movement and light.

• The two thread-like antennae extending from the head have sensory receptors that permit the cockroach to monitor its environment, detecting odours through sense organs and sense touch.

Mouthparts And Feeding

• Cockroaches have mandibular, chewing mouthparts.

• This means they have one pair of mandibles and maxillae, a labium (lower lip), and a labrum (upper lip).

• Mandibles function to tear up food, and the maxilla and labium act to manipulate, and transport the food into the mouth.

• The hypopharynx is a median, flexible lobe that acts as a tongue, helping in swallowing.

Legs And Locomotion

• A cockroach has a pair of walking legs in each thoracic segment.

• These are running and climbing legs, adapted with spines and claws to provide a good grip on surfaces.

• The legs also have sensory receptors that carry information about the environment and are useful in locomotion.

Wings And Flight

• Cockroaches have two pairs of wings: forewings and hindwings.

• Tegmina are darkly coloured, opaque, and leathery, partially covering the hindwing at repose.

• The hindwing is transparent and membranous and is used for flying.

• The wings are attached to thoracic segments and are operated by powerful muscles.

Abdominal Structures

• The abdomen of a cockroach contains 10 segments in both males and females.

• In the females, the 7th sternum is boat-shaped, forming a brood or genital pouch containing the female gonopore, spermathecal pores and collateral glands.

• In the males, the 9th sternum is boat-shaped, bearing a pair of short, unjointed leg-like anal styles.