Annelida and Basal Ecdysozoans (Segmented Worms)

all segments are identical

tiny, chitinous bristles that help anchor segments during movement

can make themselves rigid with muscle contraction

seperates segments and allows for very precise movement

paired appendages in polychaeta

band like thing on body of worms that is used in reproduction

ring...

a nonliving external layer secreted by the epidermis

a structural protein present throughout the Metazoa and abundant in vertebrate connective tissue

state of suspended animation, can stop when environment becomes too dry, they can be dormant then wake up fine later when the environment is fit

• penetrate human skin
• circulates til it gets to the intestines where it then lays its eggs
• babies hatch and it starts all over again

• 15,000 species
• metameric segmentation
• setae
• coelom
• hydrostatic skeleton

• Polychaeta- clamworms, plumed worms, scaleworms, lugworms, etc
• Oligochaeta- earthworms
• Hirudinea

• 10,000 species, mostly marine
• parapodia
• setae
• head with sense organs
• very mobile
• sedentary forms
• suspension feeders

• terrestrial and freshwater- 3,000 species
• earthworms
• setae
• hermaphroditic
• no parapodia
• clitellum

• most freshwater, 500 species
• lost setae
• superficial annuli
• hermaphroditic
• clitellum
• temporary or permanent ectoparasites
• suck blood with pharynx
• secrete numbing chemicals
• penetrate surface with proboscis

• Nematodes have a non chitinous exoskeleton
• secrete cuticle
• composed of collagen protein
• secrete chitin in exoskeleton
• appendages for locomotion

• about 70 species
• many pairs of unjointed legs
• chitin in exoskeleton
• rich in fossil records

• extremely numerous and diverse- 12,000 species
• free-living, symbiotic, and parasitic
• variety of habitats
• no legs
• longitudinal muscles only