PHYLUM ANNELIDA – segmented worms

Biology 112

AnnelidsRepresentative species: common earthworm

Longest Earthworm found in Australia

12 feet long and thick as a coke can

AnnelidsHave a coelom – fluid filled body

cavity surrounded by a mesoderm (room for organs)

Have a peritoneum (membrane in the coelom in which all organs are attached)

Have 2 sets of muscle tissue. 1. body wall muscles – to move the

worm and 2. digestive system muscles to move

food through the system

Segmented WormsTube within a

tube digestive tract with food passing through mouth to anus

Class Oligochaeta: Earthworms``It may be doubted whether there are any

other animals which have played so important a part in the history of the

world as the earthworm.``

-Charles Darwin, 1881

http://mypeoplepc.com/members/arbra/bbb/id19.html

Class Oligochaeta: Earthworms2500 speciesMany more cell layers than flat and

round wormsHave blood to carry gases to and

from body tissues (circulation)Blood in earthworms contains a red

protein hemoglobin (just like in us!)Have 5 hearts near the anterior end

Class Oligochaeta cont…More complex digestive system than

other worm phylaThey consume dirt (food and sand

particles) via mouth, pharynx, esophagus and then stores it in the crop.

After storage, food moves to the gizzard to be ground down, then to the intestine for digestion and absorption into the blood stream.

Undigested food moves out the anus

Earthworm digestion

Class Oligochaeta cont…Setae are bristles that aid in movement;

each segment has 4 setae (except first and last ones)

Complex NSReproduce sexuallyHermaphrodites

Other ANNELIDSClass Hirudinea – leeches (blood sucking

parasites)

Class Polychaeta – marine wormsFamily NereididaePlanktonic Polychaete Worm

http://beyond.australianmuseum.net.au/holoplankton/holoplankton05.htm

Terebellid Worm Larva (polychaete)

http://beyond.australianmuseum.net.au/zooplankton/zooplankton01.htm

Worm Grunting/Charming

http://www.youtube.com/watch?v=VjRxUVLxdYI

http://www.youtube.com/watch?v=IGviTYCFksE

Summary of EarthwormMovement

no skeleton; two layers of muscle moves by setae; 4 per segment

Digestion has true coelem order is as follows mouth, pharynx, esophagus, crop, gizzard, anus

Nervous system simple brain, nerve cord

Circulation 5 hearts and blood vessels

Respiration O2 in the skin; CO2 out the skin

Reproduction Sexually; male and female parts (hermaphroditic)

Excretion waste through nephridia that lead to pores in the skin

Symmetry – bilateral symmetry

Pictures for Labhttp://kentsimmons.uwinnipeg.ca/16cm05/16l

abman05/lb6pg2.htm

Practice Quiz - Onlinehttp://www.rcs.rome.ga.us/hargett/biology/wo

rms/wrmdia.htm