Week 7: Lecture 6: Invertebrates: Annelids Flashcards
Phylum Annelida
Fan worms, bristle worms, earthworms, leeches
How many species of Annnelids?
16,500 species
Physical characteristics of Annelids?
3
bilateral symmetry, coelomates, segemented bodies
Do annelids have chaetae?
yes
What are chaetae?
bristles used for movement
Environment of the annelids?
marine, fresh water and terrestrial species
Reproduction of annelids?
sexual reproduction but some can regenerate
Coelomate advantages of annelids
2
- hydrostatic skeleton
2. transport of excretory and sexual products
Type of segmentation in annelids?
function?
metameric,
allows independent movement of different portions of muscles
What are chaetae made of?
made up of chitin,
They aren’t hairs as keratin makes up hair.
Traditional classification of annelids
three classes,
polychaeta, oligochaeta, hirudinea
Modern classification of annelids?
what is is based on?
two clades: Errantia, Sedentaria
based on genetic evidence
Errant meaning
‘travelling’
Clade Errantia
5 facts
- mobile marine predators
- predators crawl on or burrow in the sea floor
- well defined head with eyes and jaws
- each body segment with prominent parapodia
- sexual reproduction with separate sexes
Clade Sedentaria
7
- aquatic or terrestrial sedentary worms
- earthworms are burrowers
- lug/fan worms are filter feeders
- leeches are ecoparasites or predators
- parapodia small or not present and few chaetae
- regeneration
- hermaphrodites
