earthgworm a nd its reproductive systemon.pptx

Earthworms have long cylindrical body.
- The body is divided into more than hundred short segments
which are similar (metameres about 100-120 in number).
- The dorsal surface of the body is marked by a dark median mid
dorsal line (dorsal blood vessel) along the longitudinal axis of
the body.
- The ventral surface is distinguished by the presence of genital
openings (pores).
- Anterior end consists of the mouth and the prostomium, a lobe
which serves as a covering for the mouth and as a wedge to
force open cracks in the soil into which the earthworm may
crawl.
- The prostomium is sensory in function

1. Biology of Earthworm A Presentation on Structure, Function & Importance

2. Introduction • Earthworms are invertebrates belonging to the phylum Annelida. • They play a crucial role in soil aeration and fertility. • Commonly called 'Farmer’s Friend' due to their importance in agriculture.

3. External Features • Body is long, cylindrical, segmented. • Body covered with moist cuticle. • Segmentation visible as ring-like structures. • Anterior end (mouth) and posterior end (anus) can be distinguished. • Clitellum present for reproduction.

4. Body Wall & Locomotion • Body wall consists of cuticle, epidermis, circular & longitudinal muscles. • Locomotion occurs by contraction & relaxation of muscles. • Movement aided by tiny bristles called setae.

5. Digestive System • Complete and straight digestive system. • Mouth → Buccal cavity → Pharynx → Esophagus → Gizzard → Intestine → Anus. • Gizzard helps in grinding food. • Intestine absorbs nutrients.

6. Circulatory & Respiratory System • Closed circulatory system with blood vessels and hearts. • Blood contains hemoglobin dissolved in plasma. • Respiration occurs through moist skin.

7. Nervous & Excretory System • Nervous system: simple, consists of nerve cord and ganglia. • Sensory cells present for touch, light, and chemical response. • Excretion through nephridia. • Maintains osmoregulation and excretion of nitrogenous waste.

8. Reproductive System • Earthworms are hermaphrodites (both male & female organs present). • Cross-fertilization occurs between two worms. • Clitellum secretes cocoon where fertilized eggs develop. • Young worms emerge from cocoon.

9. Economic Importance • Improve soil fertility by mixing organic matter. • Increase soil aeration and drainage. • Used in vermicomposting. • Serve as food for birds, fishes, and other animals.

10. Conclusion • Earthworms are vital for ecosystem balance. • Their role in soil health makes them farmers' best friends. • Understanding their biology highlights their ecological and economic significance.