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Study Of Cockroach
Transcript of Study Of Cockroach
Blood vessels are poorly developed.
Cockroaches have haemolymph as the fluid in their circulatory system.
Visceral Organs located in the haemocoel are bathed in haemolymph.
Heart of a cockroach is elongated, muscular and tube like. Haemolymph (=Blood) It is a mobile connective Tissue, composed of :-
Corpuscles mainly do the function of an immune system.
The main functions of Haemolymph :-
keeps tissues moist
transports digested food, nitrogenous wastes and hormones.
Protects the body from germs and other harmful bodies.
CAUTION: Haemolymph contains no respiratory pigments and therefore play no role in respiration. Haemocoel The body cavity in between organs whereby the hemolymph circulates through. Heart of Cockroach The cockroach heart lies mid-dorsally, in the pericardial sinus.
It consists of thirteen contractile chamber.
It is neurogenic. Q&A 1) Where is the aorta present in the cockroach heart ?
2) What is the function of alary muscles ?
3) Name the non reducing sugar agent present in high concentrations in the haemolyph of cockroach, which is characteristic of insects. Q&A Morphology of Cockroach The body of cockroach is:-
0.6-7.6 cm, in length and about 1-3 cm in width.
Exoskeleton is made of hard brown chitinous plates called the sclerites (tergites dorsally and sternites ventrally)
Sternites joined by arthrodial membrane)
The body is distinctly divided into three regions:-
Abdomen Head of Cockroach The anteriorly placed head is of hypognathus type.
It has short flexible neck called cervicum.
It is formed by the fusion of six segments.
All the sclerites of the head are fused to form a head capsule.
Sense organs - Compound Eyes, Antennae, Fenestrae
Mouth Parts- labrum, mandibles, maxillae,labium and hypopharynx.
Mouth Opening Mouth parts of cockroach Thorax of Cockroach It consists of three parts:-
Each thoracic segment bear a pair of legs
Forewing (tegmina) arise from mesothorax and hind wing arise from metathorax.
Tegmina cover the hind wings when at rest. Abdomen Of Cockroach Abdomen consists of ten segments.
In females 7th, 8th and 9th sternum forms genital pouch.
In males genital apperture lies between 10th tergum and 9th sternum.
Eight pairs of abdominal spiracles are also present. Q&A What is difference between a tergum and a sternum ?
Which wing is more delicate - Mesothoracic wings or Metathoracic wings ?
How many spiracles are there in a cockroach body ?
Do cockroaches have a neck ? If yes then what is it called ?
Do cockroaches have stalked compound eyes ? If yes then where are they placed ?
How are sclerites joined to each other ? Respiratory System of Cockroach Spiracles There are slit like openings called spiracles present on both side of the body.
There are 10 pairs of spiracles in total-
2 Thoracic spiracles
8 Abdominal spiracles
The opening of the spiracles is regulated by the sphincters. Trachea The spiracles open into silvery white ectodermal tubes known as trachea.
Three pairs of longitudinal tracheal trunks are present all along the length of the body, which are connected with each other with the help of transverse trachea.
The inner spiral cuticular thickenings of trachea are know as intima.
Just like cartilage rings of the human trachea, these spiral thickenings prevent the trachea from collapsing. Tracheoles Trachea divides into fine branches called tracheoles.
These tracheoles are devoid of intima.
Tracheoles blindly terminate in the tissues and contain a tissue fluid at distal end which plays a significant role during the diffusion of the gases. Q&A The respiratory system of cockroach includes :-
The haemolymph (blood) is not involved in respiration. Excretory System of Cockroach Excretion in cockroaches is done with the help of:-
Fat body Malpighian Tubules These are long very fine unbranched yellow colored blind tubules attached at the junction of the mid and hind gut.
They are about 100-150 in number.
Each tubule is lined by glandular and ciliated cells.
One end of the tubule floats freely in the haemolymph, while the other end opens into the hindgut. These tubules filter metabolic wastes like potassium, water and carbon dioxide from the haemolymph.
In the malpighian tubules these are converted to bicarbonates of potassium, water and uric acid.
A large amount of water and bicarbonates of potassium are reabsorbed by the cells of malpighian tubules and then transfered back to the haemolymph.
Uric acid is carried to the alimentary canal of the insect and is finally passed out through anus.
As cockroach excretes uric acid as the major metabolic waste, it is called uricotelic. Q&A Nervous System of Cockroach The nervous system of cockroach consists of a series of fused ganglia, joined by paired longitudinal connectives on the ventral side. Supraoesophageal Ganglion - Brain Supraoesophageal ganglion, also known as the brain of the cockroach lies above the oesophagus in the head.
It is formed by the fusion of three ganglion and can be differentiated into forebrain, midbrain, hindbrain.
It supplies nerves to antenna, compound eyes and frontal labrum. Ventral Nerve Cord A double ventral nerve cord extends from the sub-oesophageal ganglion to the 6th abdominal ganglion.
It bears :-
Three thoracic ganglion, namely prothoracic ganglion, mesothoracic ganglion and metathoracic ganglion.
Six abdominal ganglion present on the first, second, third, fourth, sixth and seventh segments of the abdomen. Q&A Reproductive System of Cockroaches Cockroaches are dioecious (unisexual) animals.
Cockroaches exhibit sexual dimorphism, i.e., male and female individuals can be distinguished externally. The female cockroaches bear broad abdomen, brood pouch, but lacks anal styles, as present in the males. Male Reproductive System of Cockroaches The male reproductive system of cockroaches consist of :-
Pair of Testes:-
lying on each lateral side in the 4th-6th abdominal segments.
Arise from the testes and open in the upper ejaculatory duct, at the base of utricular gland.
lies in the 6th-7th abdominal segments. It consists of long tubules, small tubules and seminal vesicles.
An elongated muscular tube from the base of the utricular gland to the male genital pore.
Phallomeres:- Female Reproductive System of Cockroach The female reproductive system of cockroach consists of :-
There are a pair of yellowish ovaries, lying laterally in the 2nd-6th abdminal segments. Each ovary consisting of 8 ovarioles.
Ovarioles fuse to form an oviduct. Oviducts from the two ovaries also kjoin to form a Common Oviduct (Vagina).
The front part of this cavity lies close to the female genital pore and hence called the genital chamber, while the posterior part is called the oothecal chamber, because during the breeding it contains ootheca.
Gonapophyses Q&A 1) Out of the following, where does the actual exchange of gases occur ?
2) What is the major structural difference between the walls of the trachea and tracheoles ?
3) Can you think of a possible fact, which would act as proof that, haemolyph is not used in the process of respiration ?
Hint: Think, what is the difference between the human blood(which is used in respiration) and haemolyph(which is not used in respiration) in terms of its constituents. 1) Malpighian tubeles are described as a blind tubule. Which end of the malpighian tubules is closed ?
The distal end which floats in the haemolymph
The proximal end which opens in the hind gut
2) In a cockroach, how many malpighian tubules are present?
a) Some nitrogenous waste are also deposited beneath the cuticle of the cockroach. Can you think of a possible process by which the cockroach excretes these waste products.
b) Give another term for that process. 1) How many ganglion are present in the cockroach nervous system ?
2) Can you explain why a cockroach does not die instantly, once his head is cut off ?
3) The supraoesophageal ganglion is placed dorsally to the alimentary canal, while the nerve cord is ventral to the alimentary canal. At which place could this change in postion be occuring?
Hint:- It is part of the Central Nervous System and it lies after the supraoesophageal ganglion and before the first thoracic ganglion 1) What are the constituents of the utricular gland ?
2) The nymph grows by moulting about 13 times to reach the adult form. This process in cockroach is know as ?
3) What are the basic morphological differences between a male cockroach and a female cockroach?