Annelids Segmented Worms

Vocabulary pharynx esophagus sperm receptacle gizzard nephridia aortic arch crop oviducts septum setae clitellum parapodia Polychaeta Oligochaeta Hirudinea

Oligochaeta “Few bristles” Earthworms Terrestrial Few setae, no parapodia

Giant Gippsland Earthworm Up to 13 feet long! Found only in small region in southeast Victoria, Australia

Polychaeta “Many bristles” Marine annelids Free living or tube dwelling Largest class Parapodia Movement Increases SA for gas exch.

Polychaeta Parapodia (Up close and personal!)

Hirudinea Leeches No setae or parapodia Mostly parasites Inject anesthesia Gain 10x body weight

Annelids in the Environment Food chain Earthworms aerate soil – Provide organic matter (castings)  “poop” Leeches – medical uses

General Characteristics Segmentation allows for more specialization Each septum limits diffusion Bilateral symmetry Hydrostatic skeleton Coelomates

Body Systems

Digestion Specialized organs More efficient digestion because each organ has a specific function

Digestion Mouth – eat Pharynx – swallow Esophagus – connect Crop – storage Gizzard – grind Intestine - digest/absorb Anus – release castings

Circulation Closed system of blood vessels Carries nutrients, O2 Thicker, larger animals! Dorsal blood vessel Ventral blood vessel 5 “hearts” (aortic arches)

Circulation and Other Systems

Excretion Nephridia – two excretory tubes per segment Nitrogenous waste and excess water are removed via nephridia Water/waste exit through excretory pores

Nervous Anterior “brain” Ventral nerve cord, with segmental branches Senses: receptors for light, moisture, T°, vibrations

Reproduction Hermaphrodites – DO NOT self-fertilize! Each passes sperm to other worm’s sperm receptacle

Reproduction Mucus cocoon is secreted from clitellum Rolls off anterior end Collects eggs/sperm as it rolls Becomes egg capsule

Earthworm Dissection

Earthworm Dissection

Compare the Guide and Reality