COCKROACH:-
· Kingdom- Animalia, Phylum- Arthropoda, Class- Insecta, Order- blattodea.
· It is generally brown or black in colour but also bright blue, green and yellow at the tropical region. Its size is 1-3 inches having two long antennas, legs.
· It is omnivorous present generally in human homes at the damp places and is the vector of several diseases.
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| Fig- Morphological structure of cockroach |
· Its body is segmented and externally covered with chitinous exoskeleton.
· Chitinous covering in each segment is called Sclerites. Sclerites- Dorsally Tergites, Ventrally Sternites and both are jointed to each other through thin, flexible membrane called Arthroidal Membrane.
· Its size is varies from 35-55mm long. Its body is divisible into Head, Thorax and Abdomen.
Head:-
· Head is triangular in shape with anterior right angle tangle and goes longitudinally to body axis.
· It consists of combination of six segments.
· A pair of compound eyes parent on the head and just in front of each a membranous socket is present which arose a antenna on each side. Antennae are act as a sensory receptor.
· At anterior ventral part a mouth is present which consists of a labrum (upper lip), a pair of mandibles, a pair of maxillae and a labium (lower lip). A Hypopharynx (tongue) enclose among them.
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| Fig- Mouth Parts of Cockroach. |
· It consists of three parts- Prothorax, Mesothorax and Metathorax.
· Prothorax connects the thorax with head called neck. It is flexible for the movement of head in all the directions.
· After this thorax all the thorax is segmented (Mesothorax & Metathorax) bears a pair of legs.
· At the Mesothorax, a pair of forewings called tagma is present. These are dark, opaque and lathery.
· At Metathorax, a pair a pair of hind-wings is present. It is transparent, membranous and covered with forewings. It is used in flying.
Abdomen:-
· It consists of 10 segments
· In female, 7th, 8th & 9th segments collectively form a brood or genital pouch, containing gonophore, spermathecal pores and collateral glands.
· In male, the genital pouch lies on the hind end abdomen. Dorsally anus at 9th-10th segment and ventrally male genital pore and genapophysis at 9th segment.
· At last or 10th segment the jointed filamentous structure anal cerci is present.
Anatomy of Periplaneta Americana:-
· Anatomically it is divisible into following organ systems.
Digestive System:-
· It is divisible into three regions- Foregut, Midgut and Hindgut.
· Foregut- Mouth+ Short Pharynx+ Narrow tubular oesophagus+ Crop (storage of food)+ Gizzard. Gizzard has chitinous plate as teeth help in grinding of food. The entire foregut is lined by cuticle.
· Midgut- It is a pipe like present between foregut and hindgut. It functions only for passage of foods. At between the foregut and midgut a ring of 6-8 tube are present which secrets gastric juice.
· Hindgut- It is broader than midgut and divisible as ileum, colon, rectum and anus then outside. At between midgut (mesenteron) and hindgut a ring of about 100-150 yellow coloured thin filamentous Malpighian Tubules are present which helps in removal of excretory product.
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| Fig- Digestive System of Cockroach. |
· It is open type of organ system.
· In which blood vessels are poorly developed and opens into homocoel. Homocoel- Haemolymph+ Visceral organs (bathed in blood or Haemolymph). Haemolymph- colourless plasma+ haemocytes.
· Heart consists of elongated muscular tube and situated along mid-dorsal line of thorax and abdomen.
· On both side of hearts, funnel shaped chamber with Ostia are present which helps in blood flow from sinus to heart and vice versa.
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| Fig- Circulatory system of hearts and Valve of heart Chamber. |
· It consists of trachea which open outside through the 10 pair of spiracles present on lateral side of body.
· The opening of spiracle regulated by the sphincters. The gases exchanged at the trachioles by digusion.
Excretory System:-
· Its excretory system is composed of malpighian tubules. All the tubules are lined with ciliated and glandular cells which are help in absorption of nitrogenous wastes and convert them into uric acid.
· Its excretory organs are present in hind gut some other additional excretory organ are also present such as- fat body, nephrocytes and urecose gland.
· It is uricotelic animal.
· Its nervous system consists of many ganglia which are jointed to each other through paired longitudinal connectives in series at the ventral side.
· In series, three ganglia are present in thorax resign and six are in abdomen region. That means it spread all over the body.
· There is a bit of nerves are also present in the head region. That means a brain is present in the head region which are made up of supra-oesophageal ganglia. Brain supply nerves to the antennae as well as eyes.
· Its eye consists of about 2,000 hexagonal commatidia due to which it receives many image of one object. This kind of vision is called mosaic vision with more sensitivity and less resolution.
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| Fig- Nervous System of Cockroach. |
· It is dioecious animal so having distinct reproductive system as male reproductive system.
Male Reproductive system
· It consists of a pair of testes each of which situated each lateral side at 4th-6th segment of abdomen.
· Testis> Vas deferens (store spermatophores)> Seminal vesicle> Ejaculatory duct> Male gonophore (ventral to anus)
· A pair of mushroom shaped gland is present at 6th-7th segment of abdomen as accessory reproductive glands.
Female Reproductive System
· It consists of a pair of large ovaries. Each of which situated each lateral side at the 2nd-6th segments.
· Each ovary consists of eight ovarian tubules or ovarioles containing a chain of developing ova.
· Ovary> Oviduct> Genital Chamber (vagina).
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| Fig- Reproductive System of Cockroach (a) male, (b) Female |
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