Annelids - Segmented Worms
General Information
- Latin: Annulus = Little Ring
- Also known as ringed worms or segmented worms
- Includes earthworms, leeches, marine worms
- Approximately 15,000 + species, ranging in size from microscopic (less than 1mm) to the Australian giant Gippsland earthworm (3m long)
- 2/3 of annelids are marine species
Distribution
- Found worldwide
Habitat
- Live in a diversity of freshwater, marine, and terrestrial habitats
- From the deepest marine sediments to soils in your backyard
Distinguishing Features
- The Annelids are coelomate and triploblastic.
- Bilaterally symmetrical
- They exhibit organ system level organization. (when two or more organs work together for a specific function).
- Their body is segmented.
- Do have parapodia for locomotion
- Invertebrate
- Long cylindrical shaped bodies made up of many similar segments
- Has Chaetae (setae) (bristles for anchorage, movement and sometimes defence)
- No hard skeleton exoskeleton (unlike Arthropoda)
- No antennae, no appendages (legs)
- No obvious head end
Annelids are divided into 3 groups (2 of which are terrestrial)
- Class: Oligochaeta - Earthworms
- Class: Hirudinidea - Leeches
- Class: Polychaeta (pol-ee-keets) - Marine worms
- Subclass: Echiura Spoon Worms
- Subclass: Errantia Free Swimming Worms
- Subclass: Sedentaria Sedentary worms
