Phylum Annelida
(Segmented Worms)
•15,000 Annelid species
•Bilaterally symmetrical coelomates
–Coelomes divided into partitions by septa
•Inhabit marine, fresh water, & moist
environments
•Has complex digestive system
•Has closed circulatory system
•Epidermis is primary gas exchange organ
•Are hermaphroditic
•Reproduce sexually by cross fertilization
•Reproduce asexually through regeneration
•3 Classes
Class Oligochaeta
• Include earthworms
• Extracts nutrients from soils
• Extremely beneficial to farming as they
enrich and aerate soils
The Earthworm
Giant Earthworm – Amazon Basin
Class Polychaeta
• Very similar to oligochaeta
• Most are marine
• Have paddle or ridge-like extensions
on segments called parapodia
• Aid in gas exchange and locomotion
Lugworm
Class Hirudinea (leeches)
• Most inhabit fresh
water, or moist
terrestrial
environments
• Feed on small
invertebrates or
are parasitic
• Have significant
medicinal value in
treating bruising,
and as a source of
Pharmaceuticals
The Leech