Phylum Annelida: Segmented Worms Body divided into repeating segments

Phylum Annelida Annelida: annulus- ring, annual Body appears to be divided into segments metamerism- each segment contains body systems, excretory, circulatory, nervous, digestive 3. Bilateral symmetry two body openings (mouth & anus) “ True” Eucoelomates- Live in every environment 7. Reproduce sexually (hermaphrodites) 8. Setae- hair or bristles- except for leeches Examples: bristleworms, earthworms, leeches

Body Systems No Respiratory- gas exchange through skin *Circulatory Complete Digestion Nervous Muscular Excretory Reproductive

* Circulatory System Closed – blood always in closed vessel Five pairs of aortic arches(hearts) Ventral and dorsal blood vessels and capillaries Hemoglobin

Digestive system Crop-”stomach”- stores food Gizzard- grinds food Intestine- nutrient absorption anus

Nervous System Pair of cephalic ganglia(bundle of nerves) Ventral nerve cord with ganglia in each segment (segmental ganglia)

Muscular System Longitudinal and Circular muscles Allows for better movement- can thrash and inch, raise head, etc.

Body wall Epithelium Circular muscle Longitudinal muscle

Excretory System Wastes processed through two nephridia(kidney) in each segment Nephridia, bladder and excretory pore

Fig. 17.14 Fig. 17.14

Reproductive System -Hermaphrodites -sexual reproduction - trochophore larvae

Trochophore larva- paddlelike, bristles Apical tuft Stomach Ciliary band Mouth Anus

Annelid development

Class Polychaeta Many setae(bristles) Parapodia(paddlelike appendages Marine Gonads only appear during breeding season Predators of small animals, prey for larger

Class Polychaeta Parapodium Head Tentacle

Polychaete Worm Predatory Jaw Tentacle Everted pharynx Palp Eye Cirrus Parapodium

Class Polychaeta Fireworm

Sedentary Polychaete Lugworm Fig. 17.5 http://arkive.org/lugworm/arenicola-marina/videos.html

Fig. 17.4 http://arkive.org/pompeii-worm/alvinella-pompejana-/video-00.html

http://arkive.org/peacock-worm/sabella-pavonina/ PEACOCK WORM VIDEO

Class Oligochaeta Few setae(bristles) Clitellum No parapodia Hermaphroditic Decomposers (aerate soil) food for larger animal Ex. Giant Gippsland earthworm, earthworms

External Structures of an Earthworm Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. External Structures of an Earthworm

Lumbricus terrestris Feed on decaying organic matter Enrich soil http://arkive.org/earthworm/lumbricus-terrestris/video-00.html

Fig. 17.1

Internal Structures of an Earthworm Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Internal Structures of an Earthworm

Fig. 17.12c

Earthworms Digestive structures: Crop: temporary storage sac after mouth Gizzard: sac with muscular walls to grind soil Intestine: stretches length of body to aid in digestion of soil Anus: wastes are removed Other structures: Setae: bristles used for movement (ventral side) Clittelum: enlarged segment; secretes mucus & contains reproductive parts Anus Setae gizzard crop Clittelum Mouth

Earthworm Reproduction-sexual Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Earthworm Reproduction-sexual

Class Hirudinea Anterior & posterior sucker-ectoparasite No setae hermaphrodites Most live in fresh water Dorsoventrally compressed(flat) Ex. leeches Feed Invertebrates Body fluids Blood

Fig. 17.21

Leeches Parasitic segmented worm Most live in fresh water Have no bristles for movement move with muscular contractions Suckers used for attachment to host Some have suckers on tail also http://arkive.org/medicinal-leech/hirudo-medicinalis/video-00.html

Secrete anesthetic during bite and release anticoagulant into blood during feeding (to keep blood flowing) Leeches were used in medical procedures years ago to “bleed” the sick remove “bad blood” now they are used in cosmetic surgery, digit and limb reattachment, and blood removal from bruises