Before we get startedBefore we get started

Anterior: head-endAnterior: head-end Posterior: tail-endPosterior: tail-end Dorsal: top-sideDorsal: top-side Ventral: bottom-sideVentral: bottom-side

Phylum AnnelidaPhylum Annelida

many marine, freshwater, and terrestrial many marine, freshwater, and terrestrial wormsworms

Ex) leeches and earthwormsEx) leeches and earthworms ““segmented wormssegmented worms””

– division of rings or segmentsdivision of rings or segments

septa/septumsepta/septum (walls) separate segments (walls) separate segments setae: setae: small, bristle-like appendagessmall, bristle-like appendages

EarthwormEarthworm

Giant Gippsland Giant Gippsland EarthwormEarthworm of of AustraliaAustralia

External AnatomyExternal Anatomy

Internal AnatomyInternal Anatomy

MusculatureMusculature

*Cuticle-*Cuticle-  thin external layer.  thin external layer. *Epidermis*Epidermis- outer cellular layer - outer cellular layer Circular muscle layerCircular muscle layer Longitudinal muscle layerLongitudinal muscle layer

Digestive SystemDigestive System

obtain food by eating through and taking obtain food by eating through and taking nutrients from soilnutrients from soil

MouthMouth PharynxPharynx EsophagusEsophagus Crop:Crop: storage compartment.  storage compartment.  Gizzard:Gizzard:  soil ground up and churned  soil ground up and churned Intestine:Intestine: digestion and absorption occur digestion and absorption occur Anus:Anus: Undigested material is voided Undigested material is voided

Earthworm Digestion AnimationEarthworm Digestion Animation

http://http://www.ncsu.edu/scivis/lessons/earthworm/Ovwww.ncsu.edu/scivis/lessons/earthworm/Overview.htmlerview.html

Respiratory SystemRespiratory System

All annelids live in moist environmentsAll annelids live in moist environments– most are aquatic.  most are aquatic. 

earthworm can survive only in damp soil.  earthworm can survive only in damp soil.  – Gas exchange occurs at body surface through Gas exchange occurs at body surface through

diffusiondiffusion– No lungs!No lungs!

Circulatory SystemCirculatory System

closed systemclosed system five pairs of five pairs of pseudoheartspseudohearts surround surround

esophagus and pump bloodesophagus and pump blood blood travels to blood travels to dorsal vesseldorsal vessel

Nervous SystemNervous System

Cerebral gangliaCerebral ganglia acts as “brain” acts as “brain” ProstomiumProstomium: tongue-like lobe above : tongue-like lobe above

mouth, allows earthworms to “feel” through mouth, allows earthworms to “feel” through soilsoil

Reproductive SystemReproductive System

Earthworms are Earthworms are hermaphroditeshermaphrodites– male and female reproductive organs present in each male and female reproductive organs present in each

individualindividual– cross fertilizecross fertilize

mate by attaching at mate by attaching at clitella, clitella, exchanging sperm, exchanging sperm, then seperatingthen seperating– sperm stored while clitellum secrete a mucous cocoonsperm stored while clitellum secrete a mucous cocoon– cocoon slides along worm to collecting sperm and also cocoon slides along worm to collecting sperm and also

eggseggs– slips off worm's headslips off worm's head– embryos develop in cocoon.embryos develop in cocoon.

What happens when an earthworm What happens when an earthworm is cut in half?is cut in half?

Can it form two separate worms?Can it form two separate worms? most organs are in anteriormost organs are in anterior can regenerate a new posteriorcan regenerate a new posterior posterior end can posterior end can notnot regenerate a new regenerate a new

posteriorposterior so, so, nono you don't get two new worms. you don't get two new worms.

Photographs, Images and text Photographs, Images and text adapted fromadapted from

http://images.google.ca/imgres?imgurl=http://http://images.google.ca/imgres?imgurl=http://kentsimmons.uwinnipeg.ca/kentsimmons.uwinnipeg.ca/16cm05/16labman05/lb6pg2_files/16cm05/16labman05/lb6pg2_files/earthworm2.bmp&imgrefurl=http://earthworm2.bmp&imgrefurl=http://kentsimmons.uwinnipeg.ca/kentsimmons.uwinnipeg.ca/16cm05/16labman05/16cm05/16labman05/lb6pg2.htm&h=480&w=640&sz=901&hl=en&stalb6pg2.htm&h=480&w=640&sz=901&hl=en&start=4&tbnid=Rvj5IZLbr72DvM:&tbnh=103&tbnw=rt=4&tbnid=Rvj5IZLbr72DvM:&tbnh=103&tbnw=137&prev=/images%3Fq%3Dearth%2Bworm137&prev=/images%3Fq%3Dearth%2Bworm%26gbv%3D2%26svnum%3D10%26hl%3Den%26gbv%3D2%26svnum%3D10%26hl%3Den%26sa%3DG%26sa%3DG