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The main excretory substance in cockroach is Uric acid.

Hind gut in cockroach originates from Ectoderm.

The cockroach has two pairs of wings which are attached dorso-laterafly to die mesothorax & metathorax. First pair of wings are thick, hard & leathery. They are called as tegmina or elytra or coverites. The tegmina covers the 2nd pair of wings during rest. The second pair of wings are thin, transparent & membranous. During rest, they remain folded below the first pairs of wings. The wings have a network of veins containing haemolymph at the time of formation. Later on. the blood dries up & tire network of veins act as an endoskeleton. Now, they are called as nervures. Hie wings are formed as evagination of the body wall between the tergum & pleuron. Well developed wings have only two layers of the cuticle. The basal part of the each wing is attached to the sternum with the help of basilar muscle. There is a pair of tergostemal muscles in each thoracic segment which are attached between the tergum & the sternum and are also called as dorso-ventral muscles. The contraction & the relaxation of the basilar muscles and tergostemal muscles are responsible for the movement of the wings.

1. Apposition image :

It is formed during moderate to bright light. It is also called as mosiac image.
The pigmented sheaths expand to make die ommatidium optically isolated in the bright light. The image of one part of the object is formed in one ommatidium. Hence, it is a distinct image. In cockroach, only mosiac vision is formed.

2. Superposition image :

It is formed in dim-light & in the night. There is contraction of the pigmented sheat. Hence the optical isolation is lost. It is an indistinct image. The image of one part of the object is formed in many adjacent ommatidia.

The Johnston organ found in the antennae are Motion Receptor.

The mouth part is cockroach that functions like tongue hypopharymx.

Malpighian tubules :

There are 72 to 90 malpighian tubules which are attached in 6 groups of 12 to 15 at the junction between the midgut & hind gut. The malpighian tubules are long & narrow tubules which are yellow and unbranched. They rennan freely suspended in the heaemolymph. The length of the tubules is about 26 mm & the the diameter is 0.5 mm. The wall of the malpighian tubules is thick & is made up to 6 large cuboidal cells. The lumen is narrow & has ciliated or brush border lining. It is surround by a peritoneum.

Physiology :

Each malpighian tubule is divisible into 2 parts-

1. Proximal half absorptive part.
2. Distal half secretory part

The distal half part of the malpighian tubule take CO₂. H₂O, sodium urates & potassium urates from the haemolymph and secrete them into its lumen. In the lumen CO₂, H₂O. react to form H₂CO₃ which dissociate to form H⁺ & HCO₃^– Similarly, the sodium & potassium utrates ionized to form Na⁺, K⁺ & urate ions. These ions react together & finally form uric acid, sodium bicarbonate & potassium bicarbonate.

Antennae, Motion receptor

Respiration in cockroach is performed by the contraction & the relaxation of the tergosternal muscles. As a result of the contraction of the tergosternal muscles, the air squeezed out which is called as expiration. The relaxation of the tergosternal muscles reduces the pressure on the trachea, as air result the air rushes into the body through the spiracles. It is called as inspiration. During rest the process of breathing in involuntary & during active phase, it a voluntary process. The exchange of gases takes place by diffusion between the trachiole fluid & tissue fluid.

It includes nerve ring and the nerve cord.

Nerve ring :

It is situated in the head around the oesophagus and consists of a pair of supra-oesophageal ganglia, a pair of circum-oesophageal connectives & a pair of sub- oesophageal ganglia. The supra-oesophageal ganglia are also called as brain and is formed by the fusion of three pairs of ganglia. The brain is a bilobed structure which has three parts-

• Protocerebrum
• Deuterocerebrum
• Tritocerebrum

The sub-oesophageal ganglia are also formed by the fusion of three pairs of ganglia. They remain situated below the oesophagus.

Biting & Chewing type

The cockroach has biting & chewing mouth parts which are also called as mandibulated mouth parts. The mouth parts are attached around the mouth ventral to the head. The mouth parts enclose a cavity in front of the mouth which is called as pre-oral cavity. It is divisible into two parts viz.—

1. Salivarium
2. Cibarium

Number of eggs in the ootheca of cockroach is 16.

7 to 10 times.

Formation of Ootheca :

The ovipositors push the fertilized eggs into the oothecal chamber in 2 rows of 8 in each row. In the oothecal chamber. the secretions of the collateral glands form a dark brown colored covering around the fertilized eggs. The resulting structure is called as ootheca. The formation of ootheca takes about 20 hours.

The length of the ootheca is 8-10 mm. It’s one end is serrated. A female cockroach forms about 20-40 oothecae in it’s life span. The female carries the ootheca for few days & finally it deposit’s the ootheca in some dark, dry & warm place. The eggs of the cockroach are centrolecithal & are covered by chitinous shell. Every egg has a minute micropyle.

It secretes outermost covering of the spermatophore.

Mushroom or Utricular gland :

It is found in 7th abdominal segment & opens into an ejaculatory duct. It consists of three types of structures-

• Seminal Vesicles : They are small & round structures which store the sperms.
• Short central tubules or Utricular minores : They are small tubules which secrete nutrients for the sperms.
• Long peripheral tubules of Utriculi majors : They are long & thin tubules. Which secrete inner layer of the spermatophore.

Anal styles are found only in male cockroach.

Number of cuticular teeth in the gizzard of cockroach is 6.

Phonoreceptors

3 pairs; total 9 segments of 5 types.

The blood in cockroach is called is haemolymph.

9 ganglia (3 + 6)

3 spiracles in cockroach.

Exoskeleton of cockroach is made up of Chitin.

The head is attached to the thorax at 90° with the help of a thin & elastic neck. It is triangular & pear shaped. The head in cockroach is hypognathus. It is formed by the fusion of 6 segments. One pair of compound eyes are situated on the head which are black & kidney-shaped.

Number of spiracles in cockroach is 10 pairs.

The structural & functional unit of compound eye in cockroach ommatidium.

Cockroach is Omnivorous.

The head of cockroach is formed by the fusion 6 segments.

Number of segments in the embryonic abdomen 11.

Peretreme elastic plate covering the spiracle in cockraoch.

All types of food (omnivorous)

It is not lined by the mesodenn.

The body cavity of cockroach is haemocoel.