Annelids Phylum Annelida: 15,000 species of Segmented Worms.
Annelids
description
Transcript of Annelids
Annelids
6S 26 Wong Nga Man
Structure
• Soft-bodied
• Consist of segments (segmentation)
• It composed of three layers of cells (triploblastic)
• Process well-developed alimentary and nervous system
• Without appendages
Locomotion
• Many annelids move by peristalsis
• They have no appendages which will interfere their motion
Reproduction
• Asexual reproduction
• by dividing into two or more pieces or by budding off ,a new individual while the parent remains a complete organism
• They use similar mechanism to regenerate after severe injury
• Example: earthworm
• Sexual reproduction
• Earthworm is hermaphrodites • They release their egg and their partner sperm into
cocoon.
3 typical examples:
• -Bristleworms
• -Leeches
• -Earthworms
Bristleworms
• It is a polychetaes.
• Are found in marine environment
• Process chetae
Earthworm
• -subterranean
• -process annular , streamlined body which allow them passage through the soil smoothly
• Secret fluid over the body to reduce friction
Leeches
• Both aquatic of terrestrial
• Blood-sucking worms
• each one of them has both female and male reproductive organ.
Fossil records
• It is rare to find a fossil of annelids since they are soft bodied
Ecological significance
• For example , earthworm can facilitate the growth of producer.
• They also support the bird’s population.
Medical use
• Both earthworm and leeched have high medical value.
The End