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JOURNAL #1 • KWL: What do you KNOW about segmented worms? What do you WANT to know about segmented worms? What have you LEARNED about segmented worms? PHYLUM ANNELIDA I. General Information 1. “annelid” means tiny rings 2. Coelomates- true body cavity w/space for true internal organs. 3. Body is cylindrical & metameric- segmented 4. Bilateral symmetry 5. Closed circulatory system 6. Most have paired setae for movement II. Class Oligochaeta 1. Earthworms w/ few setae 2. Terrestrial or aquatic A. Body Structure 1. Prostomium- 1st body segment, overlaps mouth 2. Pygidium- last body segment, overlaps anus 3. Cuticle- tough outer covering for protection 4. Muscles- 2 sets create wave-like motion; longitudinal & circular 5. Clitellum- band-like structure at anterior end 6. Setae- short bristles on ventral surface that help them cling to burrows, movement/anchoring B. Digestion/Feeding 1. Nocturnal- feed at night on leaf litter & soil (scavengers/decomposers) 2. Mouth- opening to digestive tract 3. Pharynx- acts like pump, pulling food into mouth. 4. Esophagus- tube that leads to crop 5. Crop- storage chamber for food. 6. Gizzard- grinds food before it enters intestine. 7. Intestine- absorbs nutrients from food- has folds called typhlosole that increase surface area to absorb more food. 8. Anus- solid wastes excreted here 9. Castings- squiggles of mud on soil surface “worm feces” Crop Pharynx Esophagus Ventral Nerve Cord Gizzard Intestine C. Excretory System 1. Nephridia- kidney-like organ that consists of tubes for conducting liquid waste One per segment 2. Nephridiopores- pores in skin that excrete liquid waste. D. Nervous System 1. Cerebral ganglion- bi-lobed simple brain over pharynx 2. Ventral Nerve Cord- runs length of body on ventral surface ** Sensitive to touch, light, temp., moisture E. Respiratory system • Gas exchange occurs thru diffusion thru moist skin F. Circulatory System 1. Closed Circulatory System- blood is enclosed in blood vessels 2. 5 Pairs of Aortic Arches- enlarged blood vessels that pump blood thru body 3. Dorsal blood vessel- carries blood to anterior end 4. Ventral blood vessel- carries blood to posterior end G. Reproductive System 1. Monoecious- hermaphrodites 2. Do not self-fertilize 3. Worms line up w/anterior ends away from each other. 4. Sperm released from seminal vesicles & is passed along a body groove to the seminal receptacles (receivers) 5. Eggs are kept in oviducts until “ripe” 6. After 2-3 hours of copulation, clitellum forms sticky cocoon. 7. Cocoon passes down body, picking up egg & sperm 8. Fertilization occurs in the cocoon. 9. Cocoon is deposited in moist soil where it hatches after about 3 weeks. Being a hermaphrodite is beneficial to simple animals because 1. Do not have to search out a specific mate… can mate with any worm that comes along. 2. Twice as many offspring can be produced because both can carry eggs. Seminal Vesiclesstore worms own sperm Seminal Receptacles- receive sperm from mate 5 Aortic Arches Nephridia- 2 per segment for excretion Dorsal Blood Vessel Cerebral ganglion III. Class Hirudinea 1.Leeches with no setae 2. Most freshwater, some marine & terrestrial 3.Ectoparasites that feed on body fluid of host 4.Flattened, segmented 5. 34 segments A. Digestion/Feeding 1.Anterior & posterior sucker for attachment to host 2.Jaws slice skin & begin sucking blood. 3. Secrete anesthetic- so you don’t feel bite. 4. Secrete anticoagulant- Hirudin- keeps blood from clotting while feeding. 5. Engorge until 10x normal size then drop off 6. Only need to eat every few months. B. Respiratory/Circulatory/Nervous/Excretory Same as earthworms C. Reproductive System 1. Monoecious- hermaphrodites 2. Clitellum is only present during spring when leeches usually breed IV. Class Polychaeta 1.Marine worms with many setae 2. Largest class of annelids 3. Live in coral reefs, ocean floor, crevices, etc 4. Have parapodia which look like paddles along body 5. Have sensory tentacles called cirri around mouth. 6. Reproductively- dioecious V.Economic/Environmental Importance 1. recycle nutrients to soil. 2. burrows aerate & provide space for growing plant roots. 3. Leeches used for removing excess blood after surgery for reattachment of amputated limbs. Body heals faster. 4. Part of food chain DAILY QUIZ #2 1. The structure used for grinding food in the earthworm is the a. Crop b. Nephridia c. gizzard 2. Annelida means a. Soft skin b. Tiny rings c. Flat body 3. This phylum of worms is put into different classes based on a. Method of reproduction b. Type/presence of setae c. Shape of body 4. The bristle-like structures that help earthworms move are called a. Setae b. Clitellums 5. Earthworms are a. Monoecious b. Dioecious c. crops Journal #5 • How are earthworms important to humans and the environment? JOURNAL #4 • Explain two ways being a hermaphrodite is beneficial to the earthworm. 1. Before dissecting, it is necessary for you to a. b. c. Put on a safety apron Soak your specimen in preservative Wash your specimen to remove preservative DAILY QUIZ 2. The body covering of the earthworm is best described as a. Moist cuticle b. Hard exoskeleton c. Dry & bumpy 3. Leeches a. Secrete Hirudin b. Secrete anesthetic c. Both A and B 4. The paddle-like setae that are found on the sides of polychaetes like the clamworm is referred to as a. Polychaeta b. Parapodia c. oars 5. The band-like structure used for reproduction in the earthworm is the a. Cuticle b. Clitellum c. nephridia DAILY QUIZ #4 1 2 4 3 5 a. Gizzard b. Crop c. Nephridia d. Aortic arches e. Seminal vesicles f. Seminal receptacles Journal #8 • Compare and contrast the digestive systems of the leech and earthworm.