Phylum Annelida

1. Phylum Annelida By: Esther Lien Harlan Cox Siva Gandu 5th period

2. Phylum • General Characteristics • Annelids are all bilaterally symmetrical animals. They range in size from much less than 1 mm in length to more than 3 m • Their bodies are divided into segments that may or may not be visible externally • Their body is composed of a series of ring-like segments that are specialized. • In most annelids there are usually two fluid systems, the coelom and the circulatory system, and both (if present) are involved in the excretion of waste products. • Classes • CLASS Polychaeta- Bristle worms • CLASS Clitellata- Leeches • CLASS Pogonophora- Beard Worm • CLASS Echiura- Spoon Worm • CLASS Oligochaeta- Earthworms

3. BodyPlan • Triploblastic • is a condition of the blastula in which there are three primary germ layers: the ectoderm, mesoderm, and endoderm • Most remarkable advance is segmentation or metamerism • They have Elongate body which is usually round. For polychaetes and clitellidae, the head has prostomium and peristomium which have sensory organs and feeding organs. • Trunk segmentation appears in external annuli, and it is internally separated by coelomic compartments which are also separated by septae. • Some are homonomous, with body segments mostly similar, others are heterononmous, with specialized segments

4. http://www.okc.cc.ok.us/biologylabs/Images/Animal_Images/annelida.jpg Feeding • For polychaetes and oligochaetes • Raptorial • Prey captured with Head Appendages and then swallowed as a whole • Deposit • They ingest the substrate and then they derive the nutrients from it • Suspension • They use tentacles or mucus webs to filter nutrients from fluid environment • Clitellata • Have a straight gut • It has specialized organs and accessory organs, but the digestion is extracellular • Echiura • They have a coiled gut • The mouth is by the anus and the gut is long and coiled • Pogonophora • Have no known digestive system

5. http://www.buzzle.com/img/articleImages/267419-2556-7.jpg http://coris.noaa.gov/glossary/new_annelid_186.jpg Respiration • They have no true respiratory organs. • Respiratory gas exchange through skin, gills, parapodia. • They secrete moisture from the dorsal pore • The skin has many tiny blood vessels to gather oxygen across the moist film covering it.  • Since they breathe with their whole body surface, they will suffocate if their skin becomes dry.

6. http://tolweb.org/tree/ToLimages/circulatory.jpg http://www.bumblebee.org/invertebrates/images/earthworm1.jpg Circulation • Their blood is red because it has hemoglobin • Most annelids have closed and well-develop circulation • In certain smaller forms, the circulation is reduced or absent. They have Coelomic canals that serve as their blood “channels”. • The enlarged and heavily muscular vessels at the anterior end serve as the hearts that pump the blood. • Their blood is carried from dorsal to ventral vessel in the head. • Earthworms have five pulsating blood vessels that help pump blood from the main dorsal vessel to the main ventral vessel.

7. http://johnson.emcs.net/life/images/earthworm.jpg Excretion • Each segment has a pair of nephridia which are long coiled ciliated tubes to excrete their metabolic wastes. • Blood and coelomic fluid enter these tubes where nutrients, water and salts are removed. • Their waste products are transported out of the body through the coelom by specialized excretory tubes.

8. http://tolweb.org/tree/ToLimages/eyes.jpg http://media-2.web.britannica.com/eb-media/37/73337-004-B0D75E62.jpg Response • The nerve cord has two sorts of fibers: normal and giant nerves • The nerve cord runs down the whole body . • The giant nerves are only important during rapid escape maneuvers. • Polychaeta • Bodies organized into regions according to the function and structures. • They have a well-developed head with specialized sense organs • Oligochaeta • They have no eyes, but they have many photoreceptors, chemoreceptors, and mechanoreceptors that are concentrated near the ends of their body. • They have fewer setae than polychaetes and no parapodia or head region.

9. Movement • Polychaetes • Parapodia, paired, fleshy, paddlelike flaps, used for swimming, burrowing, or slow crawling. • Fast crawling is performed by undulating the body. • Oligochaeta • Chaetae – tiny hairs that provide anchoring points for burrowing • They deform either the whole body, or segments of the body by contracting the circular and longitudinal muscles alternately • Hirudinea • Swim with snake-like motions • Use suckers to anchor themselves to objects • Non-aqueous leeches crawl by extending and contracting their body

10. Reproduction • Polychaetes • Involves separate sexes and external fertilization, usually in water away from both parents • Lack permanent gonads, the gamete producing sex organs • Gametes are produced from the germ cells in the lining of the coelom or in the septa • Oligochaeta • Hermaphrodites – each worm has both eggs and sperm • When reproducing sperm goes in both directions to and from each worm • Fertilized eggs are put in a cocoon that forms over the parent body and then falls off • Hirudinea • Internal fertilization within the female’s body. • A sperm sac passes over the eggs which are deposited inside http://image.tuorvista.com/content/diversity-living-world/earthworm-structure.jpeg

11. Works Cited "Annelida." Bumblebee.org. Web. 17 Apr. 2010. <http://www.bumblebee.org/invertebrates/ANNELIDA.htm>. Mehaffey, Leathem. "Outline for Annelids." Vassar College. 2001. Web. 17 Apr. 2010. <http://faculty.vassar.edu/mehaffey/academic/animalstructure/outlines/an nelida.html>. Ramel, Gordon. "The Annelids (Phylum Annelida)." The Earth Life Web. Web. 15 Apr. 2010. <http://www.earthlife.net/inverts/annelida.html>. Raven, Peter H., and Peter H. Raven. Biology. 6th ed. New York: McGraw-Hill, Higher Education, 2002. 906-09. Print. Rouse, Greg W. "Characteristics of Annelida." Tree of Life Web Project. 2002. Web. 16 Apr. 2010. <http://tolweb.org/articles/?article_id=57>.