Phylum Annelida (Earthworms, Sandworms, Leeches)

Phylum Annelida(Earthworms, Sandworms, Leeches)By: Veronica Weigandt

Key CharacteristicsBilaterally symmetricalClosed circulatory systemHas a nervous systemSegmentationTrue CoelomNo true respiratory organs

AnatomySegmentedIntestineAnusNerve CordCoelomSeptaDorsal/Ventral blood vesselNephridiaClitellum

Anatomy (Cont.)MouthPharynxEsophagusCropGizzard

Digestive1 way digestionFood goes into mouthPharynx helps food into mouthFood is stored in cropGizzard breaks down foodRest goes through intestines

RespirationSimple diffusionOxygen is consumed by body cellsCarbon dioxide diffuses through the body surface

Internal TransportClosed system of blood vesselsBlood pumps through bodyCirculation

ExcretionNephridium Fluid passes through nephridium into bladder-like sacSac opens through a pore in the skin & waste is discharged

ResponseHas a brainResponds to:OdorsChanges in moistureChanges in temperatureChanges in light

MovementVarious muscle groupsParapodiaSetae sinks into the groundLongitudinal muscles contract

ReproductionReproduction is sexualJoin head to tail; exchanging spermForms mocous sheathEggs get released into the sheathWorm backs out of sheathSperm gets released into the sheath & fertilization occursCocoon develops

Examples

LeechesSandwormsEarthwormsFactsOver 22,000 speciesThey live just about anywhere on earthMost are found in wet environmentsCan grow up to as long as 3 metersCan range in their color, patterning, and other features

Literature Citedhttp://www.bu.edu/gk12/eric/Annelida.pdfhttp://www.esu.edu/~milewski/intro_biol_two/lab__12_annel_arthro/Annelida.htmlhttp://www.infusion.allconet.org/webquest/annelida.htmlhttp://library.thinkquest.org/28751/review/animals/5.html#http://www.biology-questions-and-answers.com/annelids.htmlhttp://www.encyclopedia.com/topic/Annelida.aspx