Yogy's biology

  11. Study of Animal Type - Cockroach - part 08 - Interactions with mankind Interactions with mankind : Cockroach causes damage to the household materials like clothes, shoes, paper etc.  They also eat and destroy the food stuff. They  contaminate food  which gives typical smell and make it unpalatable. As they live in sewage pipes and gutter holes, they carry with them harmful pathogens causing diseases like cholera, diarrhoea, tuberculosis, typhoid, etc. Cockroach serves as a part of  food chain  also.  Many amphibians, birds, lizards and rodents prey upon them making them a part of food chain.  They are eaten by certain groups of people in South America, China and Myanmar. Cockroach is used as  experimental animal in laboratories and for biological research,  as they can be obtained easily without causing damage to ecological balance. Control Measures :  As cockroach is economically harmful organism it must be controlled in an e...

  11. Study of Animal Type - Cockroach - part 07 - Reproduction system Reproduction system : Cockroach is  dioecious  organism i.e. male and female individuals are separate. 1. Male Reproductive System :  Male reproductive system consists of -  primary reproductive organs secondary reproductive organs.  Primary sex organs (male gonads) are called  testes  which are paired and located in the  4th to 6th abdominal segments.  They produce  sperms  which are carried by  vasa deferentia.   It is a pair of thin tubular structure arising from the testes and opening into the ejaculatory duct through  seminal vesicle.  They carry sperms to the  ejaculatory duct .  Ejaculatory duct opens into  male gonopore  situated ventral to anus. Mushroom shaped gland or  Utricular gland  is accessory reproductive gland.  It is present in the  6th to 7th abdominal segments. Male gonapophyses...

  11. Study of Animal Type - Cockroach - part 06 - Nervous system Nervous system : The nervous system of cockroach consists of - Central Nervous System (CNS) Peripheral Nervous System (PNS) and Autonomus Nervous System (ANS).  Nervous system of cockroach is  ventral, solid and ganglionated. A. Central Nervous System (CNS): CNS consists of - nerve ring and  ventral nerve cord.  Nerve ring : Nerve ring  is made up of-   supraoesophageal ganglia circum-oesophageal connective and  sub-oesophageal ganglion. A pair of supra-oesophageal / cerebral ganglia is collectively known as  brain .  Brain is present in head, above the oesophagus and between antennal bases.  Each  cerebral ganglion  is formed by fusion of three small ganglia-  protocerebrum deutocerebrum and  tritocerebrum. Sub-oesophageal ganglion is  bilobed ; present below the oesophagus in head.  It is also formed by fusion of  3 pairs of g...

  11. Study of Animal Type - Cockroach - part 05 -Excretory System Excretory System : Malpighian tubules  are main excretory organs of cockroach.  They are attached to the alimentary canal between the midgut and hindgut.  They are thin, yellow coloured, ectodermal thread-like structures hanging freely in the haemocoel.  They are about  150 in number . Malpighian Tubule :  Each Malpighian tubule is lined with a single layer of  glandular epithelial cells  having  microvilli .  Their distal portion is secretory and proximal part is absorptive in function.  They extract water and nitrogenous wastes from the haemocoel and convert them into  uric acid  and pass them into ileum.  As the cockroach excretes uric acid, it is said to be  uricotelic.  In addition, the fat bodies,  nephrocytes and uricose glands  (in male  cockroach only) also help in excretion. In cockroach,  urate cells (nephr...

  11. Study of Animal Type - Cockroach- part 04 - Respiratory system Respiratory system or tracheal system : Cockroach has an  internal respiratory system  of air tubes called tracheal system, by which air is brought into the body and is in contact with every part of body.  It allows exchange of gases directly between  the air and tissues   without the need of blood. Spiracles :  Spiracles are respiratory openings. They are paired, present on ventro-lateral side of body , in pleural membrane .  Cockroaches have  two pairs of thoracic  and  eight pairs of abdominal spiracles.  The spiracles open into a series of air sacs from which the tubes called  trachea  arise. Trachea :  The trachea form a definite pattern of  branching tubes  arranged transversely as well as longitudinally.  They are about  1mm thick  and have spiral or annular thickening of chitin. The  inner lining of chitin...

  11. Study of Animal Type - Cockroach - part 03 -Circulatory system Circulatory system or blood vascular system: Cockroach has open type of circulatory system that consists of -  colourless blood (haemolymph) a dorsal blood vessel (heart and dorsal aorta) and  haemocoel. A. Haemolymph :  Haemolymph of cockroach is  without any pigment ; hence it is colourless. It consists of plasma and  seven types of blood cells  / haemocytes.  Plasma consists of water with some dissolved organic and inorganic solutes.  It is rich in nutrients and nitrogenous wests like  uric acid. B. Haemocoel :  Body cavity (coelom) of cockroach is divided into three sinuses due to two diaphragms  dorsal diaphragm ventral diaphragm. Dorsal and ventral diaphragms are thin fibromuscular septa (sing.—septum).  It remains attached to terga along lateral sides at intermittent points. Dorsal diaphragm : It has  12 pairs  (2 thoracic and 10 abdomina...

  11. Study of Animal Type - Cockroach - part 02 - Digestive system of cockroach Body cavity :  A body cavity or  true coelom  is present around the viscera. Because of the open type of circulation, the body cavity is filled up with  blood . Hence, it is called  haemocoel .  In the haemocoel, fat bodies are seen. It is in the form of loose,  whitish massof tissue .  The fat body is made up of large, polygonal cells which contain  fat globules proteins and sometimes glycogen. Digestive system of cockroach : Digestive system of cockroach consists of - mouth parts alimentary canal and a pair of salivary glands . Alimentary canal is a  long (6-7 cm) tube  of different diameters and two openings. Alimentary canal is divisible into three regions as - Foregut (stomodaeum) Mid-gut (mesenteron) and  Hindgut (proctodaeum). Mouth :  Mouth / pre-oral chamber is a narrow space bounded by mouth parts.  Hypopharynx  is pre...

  11. Study of Animal Type - Cockroach - part 01 - External morphology Habit and habitat : Cockroaches are  omnipresent  i.e. present everywhere, all over the world.  It prefers damp and moist places, crevices to live. It is omnivorous,  nocturnal and cursorial.  Three common species of cockroach found in India are- Periplaneta americana Blatta orientalis and  Blatta germanica   Systematic Position : Kingdom  : Animalia (Cell wall absent, heterotrophic nutrition.) Phylym  : Arthropoda (Jointed appendages are present, segmented body, chitinous exoskeleton. Class  : Insecta (Two pairs of wings and three pairs of walking legs are present.) Genus  : Periplaneta (Nocturnal, straight wings.) Species  : americana (Origin is in Continent of America) External morphology : Shape and size :  Cockroach has an elongated,  bilaterally symmetrical  and dorso-ventrally flattened body.  They are triploblastic, euco...