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Phylum Annelida. the segmented worms. Vocabulary Annelida. Setae 11. Closed circulatory system Parapodium 12. Proboscis Crop 13. Eucoelomate Gizzard 14. Ecology Typhlosole 15. Anticoagulant Aortic arch 16. Detritus Nephridia 17. Monoecious Clitellum 18. Dorsal
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Phylum Annelida the segmented worms
Vocabulary Annelida • Setae 11. Closed circulatory system • Parapodium 12. Proboscis • Crop 13. Eucoelomate • Gizzard 14. Ecology • Typhlosole 15. Anticoagulant • Aortic arch 16. Detritus • Nephridia 17. Monoecious • Clitellum 18. Dorsal • Seminal receptacle 19. Ventral • Chitin 20. Hirudinea 22. Polychaeta 21. Oligochaeta 23. Annelida
AnnelidaVocab 3. crop- a thin-walled portion of the gut that is used for the storage of food prior to digestion 4. gizzard- is an organ found in the digestive tract that is used for grinding up food 5. Typhlosole-dorsal flap of the intestine that runs along most of its length;function is to increase intestine surface area for more efficient absorption of digested nutrients.
6. Aortic arch- series of hearts 12. Probiscus- the tubular feeding and sucking organ 13. Eucoelomate- an organism that has a complete body cavity where the ectoderm and the endoderm is lined by mesoderm 15. Anticoagulant-substance that prevents coagulation; that is, it stops blood from clotting
16. Detritus- non-living particulate organic material; typically includes the bodies or fragments of dead organisms as well as fecal material
Agree or disagree 1. All worms are found in Phylum Annelida. 2. Earthworms are the largest group of annelids. 3. Annelids have bilateral symmetry.
Taxonomy • Kingdom: Animalia Phylum: Annelida Class: Oligochaeta Polychaeta Hirudinea
General Characteristics of Annelids • “Annellus” means “little rings” • Segmented body • ___________ symmetrical • True coelom, often divided by internal partitions…….___________ • Most have external bristles called _______ Bilaterally Eucoelomate setae
General Characteristics of Annelids - cont • Some have fleshy protrusions called ___________. • The number of setae and the presence or absence of parapodia is the basis for dividing the annelids into 3 classes: • Oligochaeta • Polychaeta • Hirudinea parapodia
Body Cavity Gut Eucoelomate completely Have a “true” body cavity that is ____________ surrounded by ___________ mesoderm ectoderm coelom mesoderm endoderm
Annelid Characteristics The Coelom closed • is a ______, fluid filled cavity that surrounds the ____. • the fluid within acts as a _____________ system ectoderm gut Skeletal
Annelida Characteristics Nervous system • Anterior nerve ring, ganglia, and ventral nerve cord Locomotion • both ___________ and __________muscles • most have __________ (chitonous bristles secreted by the epidermis) that aid in locomotion and burrowing longitudinal circular setae
Annelida Characteristics Skeletal System • fluid in coelom acts as a hydrostatic skeleton Gas exchange • mainly by diffusion through the skin
Circulatory System • complete with _______ & _______ • regional specialization Digestive System • __________ circulatory system composed of blood vessels (some of which are contractile and act as “hearts”) closed mouth anus Excretion • excretion is accomplished by organs called ___________ nephridia Reproduction *normally sexual or hermaphroditic
Protostomes • Blastopore develops into the mouth • Anus develops later in a different spot.
Mouth Formation Blastopore becomes the mouth and the anus forms secondarily Future anus blastopore archenteron (primitive gut) mouth
Questions • What kind of coelom do all annelids have? • What kind of symmetry do all annelids have? • What are setae? • How many openings to the digestive system? • What type of skeletal system do annelids have?
Class Polychaeta • all _____________ • this class contains _____ of all known Annelids. • have a well developed head with specialized sense organs marine 2/3
Class Polychaeta(Poly = many, chaeta= setae) setae • have many _______ (chitonous bristles secreted by the epidermis) • these setae are arranged in bundles on paddle-like appendages called parapodia setae
Questions 1. What does Polychaeta mean? 2. Where do you find most polychaets? • CHUNKING.. Read on pg 213 & discuss 3 external anatomical features specific to polychaetes.
Many are filter-feeders with specialized structures Class Polychaeta Extended Contracted
Class Oligochaeta The earthworm • Most familiar member:________________ • Generally live in the soil or fresh water. • Have few setae (bristles) • (_____= few, ______ = setae) • Usually feed on _________ • (decaying organic matter) • Have specialized digestive system to obtain the maximum amount of nutrients out of the detritus (e.g. gizzard, crop…) oligo chaeta detritus
Class Oligochaeta Locomotion Circular muscle contraction Longitudinal muscle contraction
Movement • Posterior setae anchor • Circular muscles contract • Anterior setae anchor • Circular muscles relax and longitudinal muscles contract Muscles contract against “Hydrostatic Skeleton”
Class Oligochaeta Reproduction • usually monoecious • Cannot fertilize own eggs • cross-fertilize by • exchanging ______ sperm clitellum testis
CHUNKING QUESTIONS • Read on page 217 • Discuss the external anatomical features specific to oligochaetes.
Class Oligochaeta – The Earthworm Feeding and Digestion • Soil is sucked into the mouth by the muscular pharynx. • Soil then passes to the crop (temporary storage area)
From the crop it moves to the gizzard • The gizzard grinds the soil • As the soil moves through the intestines, nutrients are absorbed by the blood.
The typhlosole (infolding of intestinal wall) increases the surface area for absorption. • Undigested material is eliminated through the anus.
Intestine Typhlosole
Neural Control • Most body segments contain a single ganglion (cluster of nerve cells) • Nerves branch from them • Carry impulses to the muscles • Anterior segments have several ganglion fused together brain • Process information from sensory structures
Respiration • Oxygen and Carbon Dioxide diffuse through the skin. • Skin needs to be moist • Secretion of mucus helps keep them moist
Excretion • Earthworms excrete liquid waste through long tubules called Nephridia
Circulation • Closed circulatory system • 5 aortic arches link ventral and dorsal blood vessels.
http://www.youtube.com/watch?v=A2BY0hRUA9E Dissection of Earthworm http://www.mhhe.com/biosci/genbio/virtual_labs/BL_14/BL_14.html VIRTUAL LAB
Ecology • Earthworms can be considered “mini topsoil factories” because they bring _________ up to the surface layers of the soil and assist in breaking down ________ matter. nutrients organic
Earthworm Trivia • If all the material ever moved through earthworms was piled up, the heap would rise 30miles, more than 5 times the height of Mount Everest!!
Questions • How do earthworms breathe? • How many hearts do earthworms have? • Why are earthworms so important to the soil?
Class Hirudinea • Usually freshwater but there are some marine and terrestrial species • Most are parasites • No setae • No parapodia • Have 2 suckers
Class Hirudinea proboscis • have an extendable ________ for feeding