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Phylum Annelida the segmented worms Vocabulary Annelida 1. Setae 11. Closed circulatory system 2. Parapodium 12. Probiscus 3. Crop 13. Eucoelomate 4. Gizzard 14. Ecology 5. Typhlosole 15. Anticoagulant 6. Aortic arch 16. Detritus 7. Nephridium 17. Monoecious 8. Clitellum 18. Dorsal 9. Seminal receptacle 19. Ventral 10. Chitin 20. Hirudinea 22. Polychaeta 21. Oligochaeta 23. Annelida Annelida Vocab 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 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 ANNELIDA - “fireworm” General Characteristics of Annelids • “Annellus” means “little rings ” • Segmented body Bilaterally • ___________ symmetrical • True coelom, often divided by Eucoelomate internal partitions…….___________ • Most have external bristles called setae _______ General Characteristics of Annelids - cont • Some have fleshy protrusions called parapodia ___________. • The number of setae and the presence or absence of parapodia is the basis for dividing the annelids into 3 classes: – Oligochaeta – Polychaeta – Hirudinea Body Cavity Eucoelomate completely Have a “true” body cavity that is ____________ mesoderm surrounded by ___________ ectoderm coelom mesoderm Gut endoderm Annelid Characteristics The Coelom closed fluid filledectoderm • is a ______, cavity gut that surrounds the ____. • the fluid within acts as a Skeletal _____________ system Annelida Characteristics Nervous system •Anterior nerve ring, ganglia, and ventral nerve cord Locomotion longitudinal and __________muscles • both ___________ circular setae •most have __________ (chitonous bristles secreted by the epidermis) that aid in locomotion and burrowing Annelida Characteristics Skeletal System •fluid in coelom acts as a hydrostatic skeleton Gas exchange •mainly by diffusion through the skin Digestive System Circulatory System • complete with •__________ closed circulatory mouth & _______ anus _______ • regional specialization system composed of blood vessels (some of which are contractile and act as “hearts”) 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 1. What kind of coelom do all annelids have? 2. What kind of symmetry do all annelids have? 3. What are setae? 4. How many openings to the digestive system? 5. What type of skeletal system do annelids have? Class Polychaeta Class Polychaeta • all _____________ marine 2/3 of all known • this class contains _____ Annelids. • have a well developed head with specialized sense organs Class Polychaeta (Poly = many, chaeta= setae) setae (chitonous bristles • have many _______ 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. Polychaete worms – Thermal vents Class Polychaeta •Many are filter-feeders with specialized structures Extended Contracted Class Oligochaeta Class Oligochaeta Class Oligochaeta The earthworm • Most familiar member:________________ • Generally live in the soil or fresh water. • Have few setae (bristles) oligo chaeta = setae) •(_____= few, ______ • Usually feed on detritus _________ (decaying organic matter) • Have specialized digestive system to obtain the maximum amount of nutrients out of the detritus (e.g. gizzard, crop…) Class Oligochaeta Locomotion Circular muscle contraction Longitudinal muscle contraction Movement 1. 2. 3. 4. 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 sperm exchanging ______ 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. Internal View of an Earthworm Ecology Earthworms can be considered “mini topsoil factories” because they bring _________ nutrients up to the surface layers of the soil and assist in breaking organic matter. down ________ • 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 1. How do earthworms breathe? 2. How many hearts do earthworms have? 3. Why are earthworms so important to the soil? Class Hirudinea 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 for feeding • have an extendable ________ Class Hirudinea Locomotion They use their anterior and posterior suckers _________ to move. Ecology • Although some leeches are parasitic blood suckers (can be temporary or permanent), many are predators. Ecology medicinally • Leeches have been used __________ since the 19th century. Ecology - cont • Currently they are used to increase blood flow following reconstructive surgery • Hirudin is a powerful anticoagulant that is found in the ____________ salivary glands of leeches Questions • Why are leeches used in the field of medicine? • What structures do leeches lack? • What structures do leeches use to move? Nova - Leeches Annelida Review: Write the questions & use the book & your notes to answer the questions. 1. Identify w factors used as the basis for dividing annelids into 3 classes. 2. List the advantages of segmentation. 3. How does an earthworm exchange oxygen and carbon dioxide with its environment? 4. What is metamerism? Identify 3 reasons why it is advantageous? (textbook) pg. 211 5. What is tagmatization? (textbook) 6. Identify the 3 classes of Annelids and give an example of each. 7. Use a flow chart (arrows) to trace the involvement of setae and muscle contractions as an earthworm moves. 8. Use a flow chart to trace the feeding and digestion process of earthworms. 9. What 2 structures do leeches lack? 10. How are leeches used medicinally following surgical procedures? 11. What is the function of the following structures: A. Typhlosole B. Crop C. Gizzard D. Setae E. Proboscis F. Clitellum G. Aortic arches H. Nephridia I. Parapodia 12. Identify the 3 parts of the nervous system of annelids. 13. What does “annellus” mean? 14. Which is the largest class in phylum Annelida? 15. Why do Oligochaets have a specialized digestive system? 16. How does sexual reproduction take place in earthworms? What 2 structures must line to ensure the successful delivery of sperm? 17. Explain how each class gets it’s name: A. Polychaeta B. Oligochaeta C. Hirudinea