Presentation on theme: "Worldwide distribution. Habitat: Saltwater, Freshwater, and Land. Marine. Found in benthic regions and on the surface."— Presentation transcript:
Worldwide distribution. Habitat: Saltwater, Freshwater, and Land. Marine. Found in benthic regions and on the surface.
Latin singular: Annulus Plural: Annuli Annelid Metamerization- Division of the body into a series of repeating segments. What other organisms, besides those in this phylum, are metameric? What is the evolutionary advantage to metamerization?
All Annelids (except leeches) have setae. Setae- Short hairs/bristles. Function: Anchor during movement. Short setae: land Long setae: aquatic Body segments separated by septum Septum: Internal wall Closed circulatory system Well-developed nervous system (brain + nerve cords)
Hydrostatic Skeleton: A skeleton made up of fluid under pressure in closed compartments. Circular Muscle Longitudinal Muscle Circular Muscle
Contraction of longitudinal muscles- shorten Contraction of circular muscles- lengthen Alternate muscular contractions: longitudinal, circular, longitudinal, circular, etc.