Phylum Annelida the segmented worms

Vocabulary Annelida 1.Setae11. Closed circulatory system 2.Parapodium 12. Probiscus 3.Crop13. Eucoelomate 4.Gizzard14. Ecology 5.Typhlosole15. Anticoagulant 6.Aortic arch16. Detritus 7.Nephridium17. Monoecious 8.Clitellum18. Dorsal 9.Seminal receptacle19. Ventral 10.Chitin20. 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 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

ANNELIDA - “fireworm”

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 Eucoelomate Have a “true” body cavity that is ____________ surrounded by ___________ ectoderm mesoderm endoderm coelom Gut completely mesoderm

Annelid Characteristics The Coelom ectoderm is a ______, fluid filled cavity that surrounds the ____. the fluid within acts as a _____________ system closed 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

Digestive System complete with _______ & _______ regional specialization Circulatory System __________ circulatory system composed of blood vessels (some of which are contractile and act as “hearts”) Excretion excretion is accomplished by organs called ___________ Reproduction *normally sexual or hermaphroditic mouthanus closed nephridia

Blastopore develops into the mouth Anus develops later in a different spot. Protostomes

Mouth Formation blastopore archenteron (primitive gut) Future anus mouth Blastopore becomes the mouth and the anus forms secondarily

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

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) 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.

Polychaete worms – Thermal vents

Class Polychaeta Many are filter-feeders with specialized structures Extended Contracted

Class Oligochaeta

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 The earthworm detritus

Class Oligochaeta Locomotion Circular muscle contraction Longitudinal muscle contraction

Movement 1.Posterior setae anchor 2.Circular muscles contract 3.Anterior setae anchor 4.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 ______ clitellum testis sperm

CHUNKING QUESTIONS Read on page 217 Discuss the external anatomical features specific to oligochaetes.

Class Oligochaeta – The Earthworm Soil is sucked into the mouth by the muscular pharynx. Soil then passes to the crop (temporary storage area) Feeding and Digestion

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 _________ 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 1.How do earthworms breathe? 2.How many hearts do earthworms have? 3.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 have an extendable ________ for feeding proboscis

Class Hirudinea Locomotion They use their anterior and posterior _________ to move. suckers

Ecology Although some leeches are parasitic blood suckers (can be temporary or permanent), many are predators.

Ecology Leeches have been used __________ since the 19 th century. medicinally

Ecology - cont Currently they are used to increase blood flow following reconstructive surgery Hirudin is a powerful ____________ that is found in the salivary glands of leeches anticoagulant

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 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. TyphlosoleB. CropC. GizzardD. Setae E. Proboscis F. Clitellum G. Aortic arches H. NephridiaI. 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. PolychaetaB. OligochaetaC. Hirudinea