1.Habit and Habitat
Habit and Habitat
• The name Periplaneta Americana was coined by Burmeister.
• Periplaneta Americana was a native of the tropical America. Now it has became a cosmopolitan insect.
• It is usually found in kitchens, hotels,backeries, warehouses,etc.
• It is a nocturnal insect . During day time it remains inactive and takes rest.
• Its flattened form of the body enables it to enter small crevices in the floor or walls.
• It is an omnivorous insect. Eating all types of food.
• It locates its food by the sense of smell.
• Periplaneta is a cursorial animal .
• There are about 2,600 genera of cockroaches all over the world.
• Two types of cockroaches are common in India. These are Periplaneta americana and Blatta orientalis.They are also world wide in distribution. Other species of cockroaches , which are present in India but not common ,are Blatta germanica and Blatta australiasae.
• Periplaneta americana and Blatta orientalis differ in their morphology.
1. Cockroach has an elongated , narrow,elliptical,dorso-ventrally depressed body.
2. It exhibits bilateralsymmetry.
3. The wings extend beyond the tip of the abdomen in the males.
4. The colour is reddish brown with a light yellow area around the edges of the pronotum.
5. The complete body is externally covered by a chitinous cuticle which constitutes the exoskeleton.
6. The cuticle is secreted bythe underlying cell of the hypodermis.
7. The cuticle is externally by a thin layer of wax, impermeable to water.
8. The oenocytes , are believed to secrete wax.
9. The cuticle protects the body,prevents loss of water, provides rigidity and offers place for attachment of muscles.
10. It consists of small plates or sclerites, which are joined by soft, flexible arthroidal membranes.
11. The body of cockroach is distinctly segmented and consists of three tagmata namely 1.HEAD 2.THORAX and 3.ABDOMEN.
The embryo of cockroach has preoral archecerebrum, the lost telson and in between are twenty segments.
The preoral archecerebrum with six post oral appendages form the head.
The next three segments form the thorax and the remaining eleven segments with teison form the abdomen.
In the adult archecerebrum and telson are lost. The first six segments are fused to form the head.
In the adult ,ten segments are present, while the eleventh segement is represented as epiproct and paraprocts. In cockroach epiproct is fused with tenth abdominal tergum.
1. Head is the first tegmata of the cockroach body.
2. It is small and triangular.
3. The head of cockroach is formed by the fusion of six embryonic segments.
4. The head is movably attached to the thorax by a short neck or cervicum.
1. The head capsule of cockroach is formed by the union of six sclierites. Only faint sutures are exhibited between the sclierites.
2. The head capsule has both paired and unpaired ssclierites. They are
*Two epicranial plates :- Present between the two eyes on the vertex . They are connected by lambda shaped epicranial suture.
*Alarge unpaired scleiritecalled Frons,lies below the epicranium. The Frons is the largest sclierite of the head.
* Below the Frons lies a sclierite called Clypeus.
A pair of cheek sclierites called genae lie below the two compound eyes and on the lateral sides of the frons and clypeus.
3.The sclierites of the head are immovably articulated.
4.The opening on the posterior side of the head is called occipital foramen. It is bordered by a sclierite called Occiput. Oesophagus, aorta, nervecord and tracheae pass through the occipital foramen.
5.The orientation of the head in cockroach is called Hypognathous because it is bent right angles to the longitudinal axis of the body, as a result of which the jaws are directed downwords.
APPENDAGES OF HEAD:-
1. The head of cockroach is formed by six embryonic segments.
2. The first and the third segments do not bear any appendages.
3. The second head segment bears a pair of antennae.
4. The fourth segment bears apair of mandibles.
5. The fifth segment bears a pair of first maxillae. The appendages of fourth ,fifth and sixth segments together with labrum and hypopharynx constitute the mouth parts.
1) FENESTRAE :-A pair of whitish spots is present close to the base of the antennae. They are called Fenestrae. Fenestrae represent the ocelli, which are the simple eyes.
2) ANTENNAE :-
1.Apair of antennae are present near the inner borders of the eye on the frons.
2.Each antenna has three parts .They are
A.Scape-The first segment.
B.Pedicel- The second segment.
C.Flagellum- The rest of the antenna.It is multy segmented structure.
The antennae serve as tactile and olfactory organ.` e
C.Flagellum- The rest of the antenna.It is multy segmented structure.
The antennae serve as tactile and olfactory organ.
1. A pair of dark,kidney-shaped compound eyesis present on the dorsolateral sides of the head,one on each side.
2.Each compound eye is composed of about 2000 functional units called Ommatidia,which are optically independent.
4)MOUTHPARTS:- The mouthparts of cockroach are of biting and chewing type. They include a labrum, a pair of mandibles, apair of first maxillae, a labium and a hypopharynx(tongue) .
MOUTH PARTS OF PERIPLANETA
The mouthparts of cockroach are of biting and chewing type.They include, A labrum, A pair of mandibles, A pair of first maxillae, A labium and A hypopharynx.
1) The mouth is covered by a labrum OR UPPER LIP.
2) It is attached to the lower edge of the clypeus.
3) The labrum bears gustatory sensilla on its inner surface.
4) The labrum helpa in tasting and handling the food.
1) A pair of triangular, hard, unjointed, stout, chitinised structures called mandibles is present, one on either side of mouth behind the labrum.
2) The inner margins of mandibles have teeth like structures. These teeth help to masticate the food.
3) Each mandible bears a sensory lobe called prostheca near its base.
4) Two pairs of muscles called adductor and abductor muscles help in the movement of the mandibles.
3) FIRST PAIR OF MAXILLAE:-
1) A pair of first maxillae lies behind the mandibles on each side of the mouth.
2) The first pair of maxilla has two basal segments called cardo and stipes.
3) Stipes attached to head capsule. Stipes is attached to cardo.
4) Stipes bears a small scleirite called palpifer on its outer margin.
5) Palpifer beara a five segmented structure called maxillary palp.
6) Two chitinous lobes inner lacinia and outer galea are attached to the inner margin of the stipes.
7) Lacinia is pincer like with two terminal denticles. Galea is the outer, soft, blunt and hood like structure. Galea covers the lacinia.
8) The maxillary palps are used for cleaning the antennae and the front pair legs.
4)LABIUM or LOWER LIP:-
1) The labium or lower lip is considered to be formed by the fusion of the second pair of maxillae.
2) The labium has two segments, the basal segment-Postmentum and the anterior segment-Prementum.
3) The postmentum includes two segments, a broad rectangular -Submentum and a triangular -Mentum.
4) A small sclerite called Palpiger is present on either side of the prementum. Each palpiger bears three segmented Labial palp.
5) The distal end of the prementum bears a pair of paraglossae ( comparable to galeae) and a pair of glossae (comparable to lacineae).
6) The glossae and paraglossae together constitute the Ligula.
5)HYPOPHRYNX or LIGUA:-
1) Hypophrynx is a chitinous, grooved, rodlike structure hanging into the preoral cavity.
2) Hypopharynx is also called lingua or tongue.
3) Hypopharynx divides the proximal part of the preoral cavity into a larger anterior – cibarium and a posterior – salivarium.
4) The salivary duct opens into the salivarium, at the base of the hypopharynx.