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Name: ___________________________________ Period: _____ Date: ____________________ Worm RG/Lab Flatworms (Ch.34): Phylum __Platyhelminthes___ Flatworms are the simplest creatures with __ They develop from __ bilateral__symmetry. three__ germ layers (as opposed to Porifera, Cnidaria Ctenophora that only had 2). They do not have a hollow __ body__ cavity___. __ Because they are flat, they can exchange oxygen and CO2 with the environment diffusion (their skin)__. They have no __circulatory__ through __ respiratory_ systems. They have an incomplete digestive system or __ gut_ with a single _single opening__. Things go out the consisting of a _ way they come in. Nerves and sensory organs are located at one end. This is known as _ cephalization__. parasites__, living on or in other creatures. Some Many flatworms are _ are not and are found in freshwater, marine and terrestrial (land) environments. Class Turbellaria: Planarian__, such as Dugesia species Includes the __ Feed by _ Food is ingested through a __ scavenging for__ bits of decaying plant and animal matter pharynx__ which is extended out from the body How do they get rid of excess water? Network of tubes w/flame cells (cilia) What are the cerebral ganglia, and what do they do? Clusters of nerve cells…simple brain Describe the two ways Planarians reproduce: Sexually…hermaphrodites, fertilize each other Asexually…fission, splits in the middle Color/label the diagram below. Examine the slides of Planaria. Draw and label any parts you can identify. Cerebral Ganglia Eyespot Gastrovascular cavity Nerves Mouth (pharynx) Class Trematoda and Monogenea: flukes__ Consist of parasitic __ They can live in the _ blood_, __intestines__, _lungs_, __liver__ endoparasites_. or other organs and are called _ Ones that live on the outsides of their host are called ectoparasites__. __ How does a fluke stick to its host and what else does this structure do? Anterior, ventral suckers Draws in body fluids Most flukes are _hermaphroditic_. Fertilized eggs are stored until release, where __ tens of thousands__ may be released at a time. Most have a complex life cycle that involves _ more__ _than__ __one___ host One disease caused by flukes includes _schistosomiasis_, which affects more than 200 million people each year in Asia, Africa and South America. Look at the slide of Clonorchis sinensis (Oriental liver fluke) under the microscope and identify any structures you can see Class Cestoda: Also known as _ tapeworms__, which can live in the intestines of almost all vertebrates At the anterior end is a structure known as the scolex. What is its structure and function? Hooks & suckers attach to host Behind the scolex are the body segments called __proglottids__. What happens to these during reproduction? Mature and produce eggs…up to 100,000 How can a human become infected with a tapeworm? Proglottid breaks off…onto vegetation… eaten by 1 host…in muscle…we eat that… hatches and lives in us Look at the slide of Taenia pisiformis (a tapeworm from beef) under the microscope. There are four sections. The top section is the scolex. Draw and identify the hooks and suckers. The other three sections are the proglottids, in various stages of maturity. Draw the most mature ones (4th one) and identify the ovary, uterus and testis. Roundworms (Ch.34): Phylum __Nematoda__ Roundworms have _ bilaterally_ symmetrical bodies and a fluid filled internal organs__ and _eggs/sperm_ and for space to store _ support. They have a complete digestive system, that is, one with __ two__ openings, unlike cnidarians, ctenophores and flatworms. Why is this a significant advancement? Food goes in one end and out the other…different parts specialized for different functions They have separate _sexes__. The vast majority are _free-living__ on land and in the water, and are parasites of plants and animals. Identify what the following creatures can do in humans: Ascaris: Hookworms: Trichinella: Pinworms: Filarial worms: live in intestines, feed on digested food, block intestines clamp on to intestinal wall, feed on bloodanemia In wall of intestinespain, muscle stiffness, death live in lower intestine…crawl out anus at night to lay eggs live in lymphatic system elephantiasis heartworms Look at the slides of Trichinella in muscle and draw what you see. Segmented worms (Ch. 35.2): Phylum __Annelida__ Feather-duster worms, common _ earthworms_ and __leeches__ are all members of this phylum. The phylum name means __ little rings____. These bilaterally_ symmetrical and, like mollusks, have a true organisms are _ coelem__, a complete internal body tube. What does this structure allow to __ happen when the organism moves? Different parts expand and contract independently Most have external bristles called __setae__. All organ systems are complete__. _ Class Oligochaeta: earthworm__. The most familiar member of this class is the __ Describe how it moves (and the structures involved): Anchors 1 segment (setae), contracts circular muscle, sends anterior forward, seta grab, longitudinal muscle contract pulling posterior forward. Complete or incomplete digestive tract? Explain. Complete…two openings…pharynx, crop, gizzard, intestine, anus Open or closed circulatory system? Explain. Closed…blood completely in vessels…5 aortic arches (‘hearts”) diffuse__ directly through the skin. Oxygen and CO2 _ Earthworms get rid of wastes through tubes called _ are they found? nephridia__. Where On each segment The nervous system consists of a chain of _ ganglia__ connected by a nerve cords_. Segmented worms don’t really “think” like we ventral _ do, but what can they respond to? Light, touch, chemicals, moisture, temperature, vibrations How do earthworms reproduce? Be sure to mention any special structures and their functions. Hermaphrodite…can’t fertilize self…anchors at clitellum We’ll look at the structures of the earthworm when we do the dissection. Until then, look at the earthworm c.s. (cross section) slides under the microscope and identify any structures you can see. Class Hirudinea: leeches__. Consists of about 500 species of __ They have no setae. At each end is a _ sucker__ that can attach to surfaces. What two things do they secrete when they suck blood? Anesthetic…so don’t feel it Anticoagulant…so don’t stop bleeding