Segmented Worms

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


  • Found worldwide


  • 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)

  1. Class:   Oligochaeta  -  Earthworms
  2. Class:  Hirudinidea  -  Leeches
  3. Class:   Polychaeta (pol-ee-keets)  -  Marine worms
  •  Subclass:  Echiura  Spoon Worms
  • Subclass:  Errantia  Free Swimming Worms
  • Subclass:  Sedentaria  Sedentary worms


Kingdom:   Animalia
Phylum:  Annelida
Class:  Polychaeta
Subclass:  Echiura
Order:  Echiuroidea
Suborder:  Bonelliida
Family:  Ikedidae

Ikeda sp 1

Sand Worm


Kingdom:   Animalia
Phylum:  Annelida
Class:  Polychaeta
Subclass:  Errantia
Order:  Phyllodocida
Suborder:  Aphroditiformia
Family:  Aphroditidae
Aphrodita australis

Sea Mouse 


Phylum  Annelida
Class:  Polychaeta
SubClass:  Errantia
Order:  Phyllodocida
Suborder:  Nereidiformia
Family:  Syllidae
Subfamily:  Syllinae
Megasyllis corruscans
Orange Worm

Phylum:  Annelida
Class:  Polychaeta
Subclass:  Sedentaria
Infraclass:  Canalipalpata
Order:  Sabellida
Family:  Sabellidae
Subfamily:  Myxicolinae
Tribe:  Miniclimate
Myxicola infundibulum