Earthworm_Presentation and anatomy of erathwrom.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 Presentation by Debasish Doley

2. Introduction Earthworms are invertebrates belonging to the phylum Annelida. They are segmented worms that play a vital role in soil fertility. Earthworms are commonly referred to as 'farmer’s friends' due to their contribution to agriculture.

3. Classification Kingdom: Animalia Phylum: Annelida Class: Clitellata Order: Haplotaxida Genus: Lumbricus Species: Lumbricus terrestris

4. External Features • Body is elongated, cylindrical, and segmented. • Body is bilaterally symmetrical and coelomate. • Segments are separated by septa. • The clitellum is a thickened glandular segment involved in reproduction.

5. Digestive System • Complete alimentary canal extending from mouth to anus. • Mouth → Buccal cavity → Pharynx → Esophagus → Crop → Gizzard → Intestine → Anus. • Gizzard grinds food into fine particles. • Intestine secretes enzymes for digestion and absorption.

6. Circulatory System • Closed circulatory system. • Blood is red due to hemoglobin dissolved in plasma. • Blood vessels: Dorsal vessel, ventral vessel, lateral hearts. • Circulates nutrients and oxygen.

7. Nervous System • Consists of paired cerebral ganglia (brain) above pharynx. • Connected to ventral nerve cord. • Each segment has paired ganglia controlling movements. • Sensitive to touch, light, and chemicals.

8. Reproductive System • Earthworms are hermaphrodites (male and female organs in the same individual). • Cross-fertilization occurs between two worms. • Clitellum secretes cocoon where fertilization and development take place. • Development is direct, without larval stage.

9. Economic Importance • Improve soil fertility through vermicomposting. • Aerate soil by burrowing. • Decompose organic matter. • Used as bait in fishing. • Indicator of soil health.

10. Conclusion Earthworms are essential for maintaining ecological balance. They enhance soil fertility, making them vital for sustainable agriculture. Their biology and role in nature demonstrate their importance as 'friends of farmers'.