* "Segmented worms"
* ----Include about 15,000 species.
* Example: Earthworms, leeches, clam worms.
* They all have segmented body divided by septa.
* walls of tissue.
* These organisms contain Bristols called Satae.
* They use setae to move, burrow, swim (clam works).
* These are worldwide organisms.
* These are Detrivore
* They feed on dead organic material all the way to parasites. (leeches)
Basic Body Plan
* Protosmium- head region, lots of segments.
* Pigidium- Tail end.
* Body wall has
* longitudal muscles (up and down move)
* circular muscles (forward and bacwards)
* Coeleum- filled with fluids.
* Nervous System
* Contain cerebral ganglia
* Two grey balls w/ ventral nerve cord attached that runs down length of body. * Cerebreal Ganglia also analogues to the brain.
* Circulatory System
* Ex: Earthworm
* Contains 5 hearts called arotic arches and dorsal blood vessels. * Closed system
* They contain hemobligin (iron)- carries oxygen
* Contain Nephrida. (Well developed)
* Removes waste from blood and coelum-cavity (Comparably to our kidneys) * Respiration System:
* Some breathe via Diffusion.
* Some have Parapodia
* Varies greatly.
* Both monoecious, and Dioceious species.
* All marine about 10,000 species named.
* Head region Present.
* Contain Parapodia
* Paired appendeges
* Used for swimming, digging, etc, and respiration.
* Well developedsetae (hairs)
* They don't contain a citellum
* Large part of marine foodchain.
Groups of Polychaeta
1. Sedentary polychaetes
a. Don't move alot, lazy in our world.
b. live in extreme environments.