II. Phylum PlatyhelminthesOsmoregulation & ExcretionClass TurbellariaBIO SCI 100 1st Edition Lecture 8Outline of Last Lecture I. Phylum CnidariaII. Sensory OrgansIII. Reproduction- Obelia life-cycleIV. Phylum Cnidaria: DiversityOutline of Current LectureI. Coral ReefsII. Phylum PlatyhelminthesIII. Phylum Platyhelminthes: DiversityCurrent LectureSea Anemone Anatomy: Coral Polyp Anatomy:TentaclesMouth & AnusThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.GCI. Coral ReefsPolyps secrete calcium that forms a cup, which it can withdraw into.- This calcium carbonate builds up over time as more polyps grow.- Found in shallow marine areas up to 30 meters deep.- Only tropical and sub-tropical waters.- Coral Reefs are one of the most biologically diverse habitats in the world.- Built by colonial cnidarians of calcium carbonate.- Provides food&shelter for millions of other animals.- One third of coral reefs worldwide are threatened with extinction- Coral death is called coral bleaching.- Mainly due to:- Agriculture runoff.- Coastal development.- Warming sea temperatures.II. Phylum Platyhelminthes- 4 Classes:- Turbellaria: free-living flatworms.- Monogenea: ectoparasitic flukes.- Tremetoda: endoparasitic flukes.- Cestoda: endoparastic tapeworm.- Platyhelminthmeans“Flat worm”.- 25,000 species.- Body Cavity: Acoelomate.- Triploblastic: three true tissue layers (endoderm, mesoderm, ectoderm).- Simplest animals with bilateral symmetry.- Tissues are organized into organs (two or more types of tissue together).- Cephalization evident.- Differentiated dorsal &ventral surfaces.- Acoelomate body cavity.- Three different tissues ectoderm, mesoderm ,endoderm.Nervous System- Cephalization differentiated head region- Have a branched nervous system, which shows centralization of nervous tissue- Some have more advanced sensory organs called ocelliallowing greater sensitivity to light.Cerebral GangliaCelli (eye spots)Transverse nerve cordLateral nerve cordLocomotion- In water, Turbellarians use undulating locomotion.- On surfaces, Turbellarians secrete a slime track and move forward along it using a ciliated epidermis.- Other platyhelminths are parasites and adults attach to host tissue and have no need forlocomotion.Feeding & Digestion- Digestive system: mouth, pharynx, and intestine.- Turbellarians have a mouth that opens on the ventral side and a muscular pharynx that can be extended.- Monogeneans, Trematodes&Cestodes have an anterior mouth and non-extendable pharynx.- Intestines are either simple or branched (except Cestodes).- Digestion via enzymes in the intestine; extracellular, or via specialized cells for phagocytosis;intracellular.Osmoregulation & Excretion- Canals with tubules that end in flame cells.- Flame cells have flagella that pull in water, which passes to collecting tubules.- Excess water can then be excreted from tubules via pores to the outside of the body.Reproduction- Most Platyhelminthes are monoecious and can reproduce asexually or….- Sexually: each individual produces both egg and sperm.o Asexual reproduction by transverse fission. If a planarian is cut in half, each half becomes a new individual.o Sexual reproduction: cross-fertilization accomplished by exchange of sperm and both individuals become fertilized.III. Phylum Platyhelminthes: DiversityClass Turbellaria- 5 mm to 50 cm long.- Mostly free-living.- Terrestrial and aquatic (marine and freshwater).- Many are carnivorous eating small crustaceans and nematodes.- Movement via slime production and ciliated epidermis, or…- Undulating body movements.Intestine OvaryPharynx OviductTestes Nervous systemGenital poreClass Monogenea- Adults of all species found as ectoparasiteson fish.- Common in skin, gill, and fins; not fatal.- Structural adaptations for parasitism: - Penetration glands.- Hooks.- Suckers.- Not reported to infect humans.Class Trematoda- Adults of all species found as endoparasites of all vertebrates.- Body covered by tegument, no ciliated epidermis.- Structural adaptations for parasitism (ie, penetration glands, hooks, sucker).- Humans often infected by eating juveniles encysted in undercooked/raw meat. (Such as fish) or swimming in water contaminated with juveniles that penetrate the skin.Pharynx Hooks for attachmentGenital poreOvaryIntestineTestesTypical Trematode Lifecycle:1. Adult sexual reproduction in main host's liver.2. Eggs in feces released into water containing intermediate host: snail.3. Eggs are ingested by the snail emerge as free-swimming larvae in water.4. Enter cyst stage in fish skin and muscle tissue.5. Humans are infected when they eat raw fish.Trematoda: Medical Relevance- Humans: lung, liver, and blood flukes.- Eating uncooked fish or from larvae in infected waters, that penetrate skin.- Blood and lung fluke infections: Africa, South & Central America, Asia, Indonesia.- Liver fluke infections: Europe, US, Middle East, Asia and Africa.- 40-100 million people worldwide suffer from either liver or lung fluke infections.- Schistosomiasiscaused by blood flukes infects over 200 million people worldwide.- Causes abdominal pain with headache, loss of appetite, anemia, vomiting, chest pain, fever & pneumonia & sometimes death.- Cure rates 50-95%Class Cestoda:- Head region has hooks and suckers for attachment to host.- Body is divided in segments called proglottids.- Each proglottid is a reproductive unit.- Monoecious.- Lack a digestive system: nutrients are absorbed across the tegument.- Humans usually infected when juveniles, encysted in beef or pork, are eaten.Mature Proglottid Anatomy: Class CestodaOvaryGenital