Annelida
DISSECTION
ANNELIDS
Taxonomy
Kingdom Animalia
Phylum Annelida
Class Hirudinea
(Leeches)
Class Polychaeta
(segmented sea worms)
Class Oligochaeta
(earthworms)
Annelida
 Annelid = ringed
 Examples: earthworms, leeches, segmented sea
worms, feather duster worms, tube worms
General Characteristics
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Found in all place on Earth
Over 15,000 named species
Made up of many segments called metameres
True coelomates with well-developed internal
organs and systems
Have hair-like structures called setae made of
chiton
Body Plan
 Body Plan: 3 regions: head, metameres and
pygidium (tail)
 Segmented (metameres) and have bristles (setae or
chaetae)
Segments
 Segments:
 Metameres: external segments that contain
muscles for movement
 Septa: internal segments that contain vital organs
 Clitellum: large segment containing reproductive
organs during times of mating
 Pygidium: the un-segmented tail end of the worm
Digestion
 Digestion: mouth  pharynx  esophagus  crop
 gizzard  intestines anus
 Some are filter feeders some feed on decaying matter
in the soil
Circulation
 Circulation: closed circulatory system with an
aortic arch with 5 hearts
 Blood vessels bring gases and nutrients to all parts of
the body
Respiration System
 Respiration: in most annelids, gas exchange occurs
through the skin so they have to be kept moist
 Other marine worms have gills
Nervous System
 Nervous System: consists of a brain and a central
nerve cord
 Sensory organs include eyes, taste buds, tentacles,
and equilibrium sensors
Movement
 Movement: movement is made possible by muscles
and bristles (setae)
Reproduction
 Sexual: Monoecious or
Dioecious but do NOT
fertilize their own eggs
 Asexual: fragmentation,
budding, or fission
Ecological Importance
Feed on decaying matter
2. Recycle nutrients making soil fertile
3. Aerate soil and give it structure
4. Food source to many other organisms
5. Used in medical treatments: leeches
leech therapy
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Class Polychaeta
 Over 10,000 known species
 Live in all oceans and at all depths
 Have many bristles called chaetae
 Predators, scavengers, parasites or filter feeders
Fire Worm
Fire Worm
Coco Worm
Feather Duster Worm
Tube Worms
Lugworm
Sand worm
Class Oligochaeta
 Over 10,000 known species
 Very few or small bristles called setae
 Move with peristaltic muscle movement
 Feed on decaying mater or are predators
 Live in water or in soil
Night crawlers
Mekong worm
Pot worm
Ice worm
Black worm
Class Hirudinea
 Most are parasitic, Over 700 species
 Do not have bristles
 Have suckers at each end of their bodies
 Used in medical treatments
 annelid dissection
Leeches