Cockroach: Morphology and Anatomy of Cockroach

Spread the love

Cockroaches belong to the order Blattodea, the family of Blattidae and the Genus Periplaneta. There are around 4000 different species of cockroach around the world. However, only a few of them can be found in the Indian subcontinent.

Some of the common species include – German cockroach (Blatella Germanica), American cockroach (Periplaneta Americana), oriental cockroach (Blatta Orientalis) and the brown-banded cockroach (Supari Longipalpa). To know more about the different species of cockroach and their scientific names, refer to our morphology and anatomy of cockroach notes.

Cockroach

Brown/black body, bright yellow, red & green in tropical.
Size 1/4th inch to 3 inches (0.6 -7.6 cm), long antennae, legs, the flat extension of upper body conceals Head, serious pests, reside in human homes.
Nocturnal omnivores, damp place throughout the world.

Morphology of Cockroach

Segmented, divisible to head, thorax, abdomen.
The chitinous exoskeleton, hardened plates – Sclerites (tergite dorsally & sternite ventrally), joined by thin & flexible articular membrane.
Adults – Peri planta Americana (34 – 53 mm), wings extended beyond the tip of the abdomen in males.

Head – triangular, anteriorly at 900 to the body axis, a fusion of 6 segments, mobility in all direction (flexible neck), bears compound eye. Thread is antennae from sockets in front of the eye.
Antennae – Sensory receptor, monitor Environment.
Anterior mouth – Biting & chewing.
Mouth – Labrum (upper lips, pair of mandibles, pair of maxillae, labium (lower lip)
Median flexible lobe acting as the tongue (Hypopharynx) within the cavity by mouth.
Thorax – Prothorax, mesothorax, metathorax.
The Head is connected to the thorax by the neck (short extension of prothorax). Each thoracic segment – pair of legs.
First pair of wings – mesothorax, Second pair – metathorax

Forewings (mesothoraces) – tegmina are dark, opaque, bather, cover hind wings at rest.
Hind wings – Transparent, membranous, flight.
Abdomen in male and female – 10 segments (jointed filamentous structure- anal cerci)
In female – 7th sternum (boot shape) and with 8th & 9th form brood/genital pouch where anterior has gonopore, spermathecal pore, collateral glands.
In a male, genital pouch (hind end of the abdomen) dorsally by 9th & 10th terga, ventrally by 9th sternum, has a dorsal anus, ventral genital pore & gonapophysis, bear short, thread-like anal styles (-in females)

Anatomy of Cockroach

1 .Digestive System of Cockroach

Foregut + midgut + hindgut
The mouth opens to the tubular pharynx to the esophagus (tubular passage), opens to sac-like structure – crop (store food), followed by gizzard/ proventriculus.
Outer thick circular muscle, inner cuticles are forming six chitinous plate – teeth.
Gizzard in grinding food. The foregut is lined by the cuticle. 6-8 blind tubules – hepatic/gastric Calca at the junction of fore & midgut, secrete digestive juice.
At the junction of mid & hindgut – ring of 100-150 yellow color thin filamentous Malpighian tubules (remove products from hemolymph)
Hind gut is broader (ileum + colon + rectum) than mid-gut.
The rectum opens through the anus.

Click Here for Complete Biology Notes

2. Vascular system of Cockroach

Open types, poorly developed vessels, open to hemocoel.
Visceral organs in the hemocoel are bathed in the hemolymph.
Hemolymph – colorless plasma + hemocytes.
Heart – Elongated tube along the mid-dorsal line of thorax & abdomen, differentiated to a funnel-shaped chamber with Ostia on either side. Blood from the sinus enters through Ostia, pumped anteriorly to sinuses again.

3. Respiratory System of Cockroach

Network of the trachea, open through 10 pairs of small holes – Spiracles (lateral side), opening by sphincters.
Branching tubes (tactual tubes -tracheoles) carry O2 from air to all parts.
Exchange of gases at tracheoles by diffusion.

4. Excretion system of Cockroach

Malpighian tubules (glandular & ciliated cell)
Absorbs nitrogenous waste – uric acid – excreted by hindgut.
Uricotelic, fat body, nephrocyte, reverse glands also help in excretion.

5. Nervous system of Cockroach

Fused, segmentally arranged ganglia, joined by C.T. on ventral.
Three ganglia in the thorax, 6 in the abdomen; spread throughout.
Head holds bit nervous system, rest along the ventral side.
If the Head is cut off, it will live for one week.
Brain by supraesophageal ganglion (nerve to antennae & compound eyes).
Sense organs – antennae, eyes, maxillary palps, labial palps, anal cerci.
Compound eye – Dorsal side, 2000 hexagonal ommatidia (receive several images) – mosaic vision (increase sensitivity decrease resolution), common at night (nocturnal).

6. Reproductive system of Cockroach

Dioecious, well developed.
Male – pair of testes on the lateral side of 4th – 6th abdominal segment, from them vas deferens arise opening to ejaculatory duct through seminal vesicle, then to male gonopore on the ventral side to the anus.
Mushroom shape gland (6th – 7th) – accessory gland.
External genitalia – Male gonapophysis/phylloxera (chitinous asymmetrical structure).
Sperms in the seminal vesicle, glued to form spermatophore.
Female – Two large ovaries, laterally in 2nd -6th segment.
Each ovary – group of 8 ovarian tubule(ovarioles) containing chain of developing ova.
Oviducts unite to a single median oviduct, opens to the genital chamber. Pair of spermatheca (6th) opens to the genital chamber. Fertilized eggs are enclosed in capsule – Oothecal (Dark reddish to blackish capsule),3/8 inch (8mm) long.
Dropped to suitable surface (crack of high humidity near food sources).
Female produce 9-10 oothecal (14-16 eggs), pest spoil food (smelly excreta), diseases.
Many are wild, no economic importance, thrive in or around human habitat.
P. americana – paurometabolous (div. by nymphal stage), nymph looks like adult, grows by molting about 13 times to reach adult form.
Next to last nymphal stage has wing pads; only adults have wings.