Oligochaeta: Oligo- long hairs
Examples:
- About 10,000 known species
- These organisms make up almost half of the Annelida phylum
- Lack parapodia, which are paired appendages which are bristle-bearing and muscular; assist with movement, respiration, and sensation
- Few bristles and chaetae
- Have pharynx to help suck in food
- Includes terrestrial, freshwater, and marine organisms
- Can be as small as 0.5 millimeters and can grow to be as large as 2 to 3 meters long
- Segmented organisms
- Have various habitats such as the soil, wells, marshes, swamps, under rocks, on the seashore, in the leaves of tropical trees and vines, or on the surface of glaciers.
Examples:
- Earthworm (Lumbricina)
- Naididae
- Enchytraeidae
- Lumbriculidae
Polychaeta: Poly- much hair
Examples:
- Have parapodia on each segment of their bodies, which are bristle-bearing
- Also known as “bristle worms”
- Are a marine class for the most part
- Can tolerate extremely cold temperatures to extremely hot temperatures depending on the species
- Have adapted to many niches such as burrowing and swimming
- Simple structures
- Some species have eyes, others can only differentiate between light and dark, while others are blind
- Have antennae
Examples:
- Nereididae
- Serpulidae
- Sabellidae
- Lugworm (Arenicola marina)
- Polynoidae
- Siboglinidae
- Terebellidae
- Eunicida
- Canalipalpata
- Scolecida
- Sabellaria
- Pectinariidae
- Myzostomida
- Aeolosomatidae
- Canadia
- Paraonidae
- Aciculata
Hirudinea: Leech
- 700 species
- 34 body segments
- Parasitic organisms
- Can range from 1 centimeter to 20 centimeters
- Some suck on blood of their host
- Have teeth to latch onto their host and numb the pain, making the host unaware that they are there
- Have suckers
- Reproduction involves internal fertilization
- Active at night, and hide during the day