Comparative anatomy & Physiology of Excretion in Invertebrates.pptx

Comparative anatomy & Physiology of Excretion in Invertebrates

1. Comparative anatomy & Physiology of excretion in Non chordate Dr. Sonia Bajaj Assistant Professor Department of Zoology Shri Shankaracharya Mahavidyalaya ,Junwani ,Bhilai

2. Introduction Removal of waste products from the body is called excretion . Waste products are synthesized in the cells due to metabolic activity. Excretion is an essential process in all forms of life. In one celled organisms, waste are discharged through the surface of the cell. The higher plants eliminate gases through the stomata or pores present on the leaf surface. Multicellular animals have special excretory organs. Ammonia, urea and uric acid are the major forms of nitrogenous wastes excreted by the animals. Ammonia is the most toxic form and requires a large amount of water for its elimination, whereas uric acid, being the least toxic, can be removed with a minimum loss of water. On the basis of main excretory products, animals can be divided into 3 groups – ammonotelic , ureotelic and uricotelic .

3. EXCRETORY ORGANS Excretory organs in Non chordate animals are – P rotonephridia , N ephridia , M alpighian tubules , A ntennal glands etc . Protonephridia or flame cells are the excretory structures in Platyhelminthes (flatworms, e.g., Planaria), rotifers, some annelids and the cephalochordate - Amphioxus. Protonephridia are primarily concerned with ionic and fluid volume regulation i.e., osmoregulation. Nephridia are the tubular excretory structures of earthworms and other annelids. Nephridia help to remove nitrogenous wastes and maintain a fluid and ionic balance. Malpighian tubules are the excretory structures of most of the insects including cockroaches. Malpighian tubules help in the removal of nitrogenous wastes and osmoregulation . Antennal glands or green glands perform the excretory function in crustaceans like prawns.

4. Excretory system in invertebrates PROTOZOA Amoeba are unicellular eukaryotes with no cell wall . They reproduce using binary fission and move by the use of pseudopodia . Pseudopodia are false feet that extend out, and then the rest of the body follows . Amoeba are found in ponds, rivers and on the surface of leaves and plants . • No special excretory organ, contractile vacuoles function as excretory organs . • Ammonia and excess water in the body.

5. PORIFERA Porifera has a very simple method that utilizes a water flow system to get rid of its useless waste materials. Excretion occurs through both the oscula and the surface of the sponge. They have numerous pores on their body that are used for the intake of nutrients and a single large opening at the top called osculum which helps in excretion. This process involves the diffusion of waste products particularly ammonia into cells and archeocytes transporting waste particles through the mesophyll and into the out going water current to prevent a blockage of the Ostia and release waste particles into the environment.

6. COELENTERATE Coelenterate oxygen consumption and carbon dioxide production was done by the entire body surface by diffusion. Similarly expenditure to metabolic wastes carried by diffusion through the entire body surface. Mouth and swallowing function fore moving food waste because coelenterate not have anus. excretion are carried out through the body surface by diffusion . Ammonia is the chief excretory waste. In marine cnidarians, the osmotic pressure of his body by seawater. Having a permeable body surface sea water so that the osmotic pressure of body fluids go up or down depending on changes in seawater salinity.

7. PLATYHELMINTHES The excretory system of numerous comprises protonephridia called flame cells . These flame cells are connected with an intricate system of excretory ducts . Flame cells are modified mesenchymal cells which are found distributed throughout the mesenchyme. The main oval part of each flame cell is called cell body or flame bulb . Nucleus is situated in the flame bulb . Each flame cell has an intracellular cavity in which hang few long cilia, each arising from a basal granule situated in the cytoplasm . All the cilia collectively form a tuft whose beating appears like flickering of the flame hence these cells are called flame cells. The lumen inside the flame bulb narrows in the elongated portion of the cell in the elongated portion of the cell in the from of a five canaliculus hence flame cells are called protonephridia. The lumen of the flame cell is in continuation with the microscopic excretory or capillary ducts. The capillary ducts from a few protonephridia open into narrow collecting tubule. Several such tubules open into larger twigs which in turn open into vessels. The excretory vessels of the anterior part of body open into four trunks . Excretory canal These four trunks unite posteriorly to form a single longitudinal excretory canal. This longitudinal excretory canal extends up to posterior end of the body where it opens out through single excretory pore.

8. NEMATHELMINTHES Ascaris has a 'H' shaped simple tubular excretory system . Excretory system chiefly consists of two longitudinal excretory canals . Each longitudinal excretory canal is extended throughout the length of the body inside one lateral epidermal cord and is closed at both the ends. The longitudinal excretory canals of both the sides are connected together transverse canals below the pharynx. A short terminal excretory duct extends from the left side the network transverse canals to the excretory pore. Unique excretory system of Ascaris is formed by a long, giant cell in the cytoplasm of which tunnel-like structures form excretory canals. This cell is called Rebette cell. Its nucleus is situated on the left excretory canal near the connecting bridge . Ascaris is a urcotelic animal excreting urea as excretory material. Due to the pressure of pseudocoelomic fluid, ultrafiltration of excretory material occurs in the excretory canals from where they are eliminated through the excretory pore. Small amount of ammonia and urea are also eliminated through the anus along with faces. Thus, it is also a ammonotelic animal .

9. ANNELIDA Excretory System In earthworms, excretion occurs by numerous microscopic coiled tubes called nephridia. These nephridia are found in all the segments of body except the first three segments. According to their location, nephridia are of three types Pharyngeal –are enteronephric Integumentary –are exonephric Septal nephridia –are enteronephric Physiology of Excretion The glandular cells of the nephridia eliminate excretory substances and excess water from the blood. Septal nephridia remove excretory substances from the coelomic fluid also . Pharyngeal and septal nephridia discharge the excretory substances into the intestine while the integumentary nephridia discharge the excretory substances on the outer surface of the body. Earthworms are mainly ureotelic i.e., excrete urea. Besides this small amount of ammonia and creatinin are also excreted .

10. ARTHROPODS The excretory system of the adult Prawn (crustacean) consists of a pair of antennary or green glands , a pair of lateral ducts and a single renal sac. each green gland consist 3 part -1 end sac 2. labyrinth 3. bladder . A. antennary or green glands- 1 End sac - This small bean-shaped part contains a blood lacuna. Its wall is /two- layered, the inner layer is of epithelial cells having excretory function and the outer thick connective tissue layer has minute lacunae. 2. labyrinth- Present outside the end sac and contains many narrow, branched and coiled excretory tubules. Each tubule communicates with the end sac by a single opening but opens within the bladder through several apertures . 3. bladder- It is a largest part of antennary gland with an epithelial lining. It communicates with the exterior through a small ureter . B. lateral ducts – A narrow lateral duct arise from the posterior part of bladder of each antennary gland . C. Renal sac- It is a large thin walled sac like structure and above the cardiac stomach. Physiology of Excretion There are two functions of antennary glands-excretion and osmoregulation. This gland is richly supplied with blood thus it removes nitrogenous excretory substances as well as excess water from the blood. The excretory fluid from end sac passes into labyrinths where useful materials are reabsorbed by selective reabsorption. The remaining fluid is collected in the bladder as urine from where it is eliminated through the renal apertures.

11. MOLLASCA They have one or two pairs of kidneys or organs of bojanus in pila and keber's organ for excretion in unio. Excretory System of Pila The excretory organ in Pila is the kidney. It consists of two renal chambers — one anterior and the other posterior . It is coelomic in origin, being a true coelomoduct, opening at one end, into the coelom (pericardial cavity) and at the other, to the exterior (mantle cavity ). Right anterior chamber: It is oval in shape. It is red in colour. It is present anterior to the pericardium. It opens into the branchial cavity of palial complex. The second side opens into the posterior chamber . The cavity in this chamber is reduced. It shows a number of lamella. They are supplied with blood They take excretory wastes from blood and send ink branchial cavity. B . Left Posterior Chamber: It is broad lobe. It is brown in colour. It is present on the left side of Hepato-pancreas. It has big lumen. Its one end opens into pericardium through reno -pericardial-aperture. The other end is connected with anterior chamber . Physiology of Excretion The two chambers will absorb nitrogenous waste materials present in the blood supplied to them. Thus collected nitrogenous waste materials will be sent into branchial chamber and finally sent. Pila in water excretes ammonia. It is ammenotelic animal. When pila is moving on land it will excrete urea it is called ureotelic animal . Tolerance to water is very high. Osmotic pressureof the internal fluid varies widely depending onthe water content of the environment. To avoidexcessive water loss, slugs or snails are moreactive at night and when the dry growingconditions, keoang will shelter to immersethemselves into the ground and covered with asort of operculum shell derived from theissuance of mucus.      

12. ECHINODERMATA Sea star lacks specialized excretory organs. The excretory substances produced by the tissues of the body diffuse out into the coelomic fluid where they are engulfed by the amoeboid coelomocytes. These amoeboid coelomocytes laden with excretory substances finally pass out of the body through the papullae . Besides, some amount of excretory substances are also eliminated by tube feet through diffusion . In sea star, the excretory product is mainly ammonia.

13. References A textbook of chordate-H.S . B hamrah & kavita Juneja Invertebrate Zoology-P.S . Dhami & J.k . Dhami Modern text book of Invertebrate-R Kotpal Invertebrate Zoology 14 edition-Jordan & Verma