The Indian Earthworm.pptx

General discription of Pheretima posthuma, for Educational and competitive exams. Useful for NEET, NET, PGT, TGT, TET, SET, SSC, PG, UG, and other exams.

1. The Indian Earthworm Part – 1 By- Dr. Mohit Tiwari

2. The Indian Earthworm Pheretima posthuma Basic description for 10+2 all boards, different competitive exams and NEET By Dr. M.K.Tiwari

3. The Indian Earthworm Pheretima posthuma Described by Prof.K.N.Bahl (1926) Other Indian forms of Earthworms are Drawida and Megascolex from South India, Eutyphaeus and Pheretima is of Gangatic plains of north india . Lumbricus is originally not an Indian form it is of Europe and North America

4. Classification – Kingdom – Animalia Phylum - Annelida Class - Oligochaeta Genus - Pheretima Species - posthuma Body looks like made up of Rings (Annulus) so called annelida , True coelomate , Triploblastic , Body shows external as well as internal segmentation, internally divided by partitions called septum. Body is tubular cylindrical with tubular intestine so called tube within the tube organization. Coelomic cavity filled with coelomic fluid which act as hydraulic endoskeleton which gives the tubular shape to the body.

5. Habits , Habitat, Shape and Size Terrestrial, Lives in burrows in most soil. Nocturnal- active in night, in damp and cloudy weather of rainy season. Makes burrows by eating the soil. Bilaterally symmetrical, Elongated, Tubular, cylindrical body. Metameric segmentation. Deep brown or clay colored due pigment porphyrin 15-20 cm x 3-5 mm in size, 100-120 segments in body called metameres or somites

6. Morphology of Earthworm

7. Dorsal & Ventral view of Earthworm

8. General characters- Mouth - Anterior terminal with Prostomium with Thigmo , Thermo, Chemo sensitive receptors for sensitivity of Touch, Temperature, Chemicals and pH. Prostomium is followed by 1 st segment of body called Peristomium surrounding mouth opening. Anus – Posterior terminal Clitallum - Circular girdle like band on 14, 15 and 16 th segment of body well developed in breeding season. Locomotion in earthworm takes place by help of S shaped chitinious structure called Setae. Present in all segments of the body except 1 st and last segment.

9. Mouth of Earthworm

10. Dorsal view- Dorsal side of body shows a mid dorsal line on body from 2 nd to last segment of body due to dorsal blood vessel.

11. Ventral view- Ventral view of earthworm shows one female gonopore on mid ventral side of 14 th segment covered with clitallum . one pair male genital pore on ventrolateral side on 18 th segment. Two pair male genital papilla on ventrolateral side of !7 th & 19 th segment of body.

12. Digestive system- Tube with in tube organization. Alimentary canal from 1 st to last segment of body. Mouth – anterior terminal on 1 st segment surrounded by peristomium , prostomium in front of mouth on dorsal side. Buccal cavity - 2 nd segment. Pharynx- 3 rd & 4 th segment. Oesophagus - 5 th to 8 th segment Gizzard - 8 th segment. Stomach – 9 th to 14 th Pre typhlosolar intestine – 14 th to 26 th Intestinal caeca - 26 th - 22 nd segment. Typhlosolar part of intestine – 26 th – 80 / 100. Post typhlosolar intestine / Rectum – 80/100 to last segment. Anus – posterior terminal end of last segment.

13. Function of different parts of gut - Prostomium for detection of taste and pH of food. Pharynx with chromophill cells secretes mucin and proteolytic enzymes. Esophagus – in some species secretes CaCO3 to neutralize acid in food. Gizzard for grinding of food. Stomach - secretes digestive enzymes for digestion of food. Pre typhlosolar intestine – digestion of food. Intestinal caeca – secretes starch digesting enzymes. Typhlosolar region of intestine for absorption of digested food. Typhlosole – Thick dorsal fold like villi on dorsal side of intestine to increase surface area for absorption. Rectum – for storage of undigested food. Fecal matter of earthworm contains large quantity of nitrogenous contents secreted by excretory structures septal nephredia .

14. Nervous system - Simple, from 3 rd to last segment of body. Supra pharyngeal ganglion one pair on dorsal side of pharynx in 3 rd segment. Circum pharyngeal connective from 3 rd to 4 th around pharynx to connect supra pharyngeal ganglion with sub pharyngeal ganglion (Fused)on mid ventral side of 4 th segment. Ventral nerve cord from 4 th to last segment of body forming segmental ganglion in each segment, Two pair nerves from each segmental ganglion and one pair nerve from inter segmental area.

15. Further studies - Bhal Karm Narayan (1947), “The Zoological memoirs Pheretima (The Indian Earthworm)” Lucknow Publishing House, Lucknow Tiwari Mohit Kumar (2021), “Bionomics, Distribution, and Relationships of Earthworms”. Anusandhan , Part-9, Vol-1, P.P.- 46-50

16. The Indian Earthworm Pheretima posthuma Part – 2, In Next video

17. The Indian Earthworm Pheretima posthuma Part – 2 By- Dr. Mohit Tiwari

18. The Indian Earthworm Pheretima posthuma Basic description for 10+2 all boards, different competitive exams and NEET By- Dr. Mohit Tiwari

19. Circulatory system of Earthworm Blood of earthworm is red in colure without RBC, Hemoglobin ( Erythrocruanine ) is dissolved in plasma for oxygen transport. Respiration through skin.

20. Blood vessels- Dorsal blood vessel – 1 st to last segment, on dorsal surface of intestine, thick walled, Blood flow Post -> Ant. Ventral blood vessel - 1 st to last segment , on ventral side of intestine, blood flow from Ant -> Post. Supra oesophageal _ 8 th -14 th just above oesophagus Lateral oesophageal from 1 st to 14 th , blood flow Ant -> Post. Placed on ventrolateral side of gut. Sub neural blood vessel – formed by fusion of lateral oesophageal blood vessel, extends from 14 th to last segment below ventral nerve cord, blood flow from Ant-> Post Hearts- 4 pairs 2 pair anterior lateral hearts , with 4 pairs of valves inside, in 7 th & 9 th segment, connects dorsal and ventral blood vessel. 2 pair lateral oesophageal hearts in 12 th & 13 th segments, connects supra oesophageal and dorsal blood vessel with ventral blood vessel, contains 3 pair of valves . Anterior loops – 2 pair, no valve, connects lateral oesophageal with supra oesophageal blood vessel.

21. Hearts- 4 pairs 1.anterior lateral hearts , with 4 pairs of valves 2. lateral oesophageal hearts , contains 3 pair of valves .

22. Excretion – Removal of metabolic waste by help of nephridia . Earthworm is ureotelic animal i.e. Urea is formed as main excretory material. Nephridia are of 3 type- Pharyngeal nephridia - in 4 th , 5 th , and 6 th segment asmass of cells, opens in pharyngeal chamber, Entronephric . Integumentary nephridia - V shape, distributed all over the skin except 1 st & last segment, 200-250 /segment, 2000-2500 in 14 th ,15 th &16 th segment in region of clitallum called nephridial garden, Exonephric . Septal nephridia - Along with septum, from 15/16 segment to last segment , 40-50 in each row 80-100 per segment, Twisted loop like , opens in intestine after 26 th segment, through dorsal excretory canal , Entronephric .

23. Pharyngeal nephridia - I n 4 th , 5 th , and 6 th segment as mass of cells, opens in pharyngeal chamber, 6->3 rd , 5 th ->4 th and 4 th ->4 th segment, Entronephric .

24. Integumentary nephridia – V shape, distributed all over the skin except 1 st & last segment, 200-250 /segment, 2000-2500 in 14 th ,15 th &16 th segment in region of clitallum called nephridial garden, Exonephric .

25. Septal nephridia - Along with both side of septum, from 15/16 segment to last segment , 40-50 in each row 80-100 per segment, Twisted loop like , opens in intestine after 26 th segment, through dorsal excretory canal , Entronephric .

26. Septal nephridia

27. Reproductive system of Earthworm Earthworm is a bisexual (Hermaphrodite). Female system – Ovary one pair attached with 12/13 segment, Oviduct 1 pair from 13 to 14 segment, Female genital opening single on mid ventral side of 14 th segment Male system - Testes 2 pair 9/10 & 10/11, testes sac 2 pair in 10 & 11, Seminal vesicle 11 & 12, vasaeffrentia 2 pair from 10 th & 11 th to 18 th segment, one pair prostate gland between 17 to 20 segment, Male genital pore one pair in 18 th segment ventrolateral position, male genital papilla 2 pair ventrolateral in 17 th & 19 th segment.

28. Accessory reproductive structure - Spermathecae – 4 pair in 6 th , 7 th , 8 th and 9 th , segment opens at 5/6,6/7,7/8,8/9 segment on ventrolateral side, bilobed sac like structure for storage of sperms during copulation. Clitallum - a proteinaceous girdle like structure on 14 th , 15 th and 16 th segment ,forms cocoon containing fertilized eggs.

29. Copulation in earthworm

30. Copulation and cocoon formation Breeding/ copulation takes place in early morning of rainy season. Earthworm is bisexual animal but copulation and cross fertilzation takes place, sperms of earthworm are transferred in spermathecae of each other. Ova are released in clitallum which slides in anterior direction, while passing over spermathecae sperms are released in clitallum where external fertilization takes place. Clitallum is released in soil as cocoon where development of embryo takes place. In 8-10 weeks 1 or 2 young earthworms are formed in each cocoon. Several cocoons are formed after single copulation

31. Habit, habitat and economic importance - Found in moist soil up to depth of 35 -45 c.m . Not found in very strong acidic or alkaline soil. Active and breeds only in rainy season as this is a cold blooded animal, in rest of the time lives in deep soil. Feeds on soil (Detritus mode of feeding), utilizes organic material present in soil. Economically very important also called friend of farmers, as they increase fertility of soil by adding nitrogen rich fecal matter and also increase soil porosity or soil aeration. END

32. Further studies - Bhal Karm Narayan (1947), “The Zoological memoirs Pheretima (The Indian Earthworm)” Lucknow Publishing House, Lucknow Tiwari Mohit Kumar (2021), “Bionomics, Distribution, and Relationships of Earthworms”. Anusandhan , Part-9, Vol-1, P.P.- 46-50