Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Pop Quiz 2 • Give the dominant body form for each – Scyphozoa – anthozoa • List 2 causes of coral reef damage. • What is the function of a colloblast? Phylum Platyhelminthes Flatworms - the Simplest Bilateral Animals Bilateral Body Design • cephalized – sensory organs concentrated in head • body directions: Triploblastic Body Design based on Hickman Fig. 14-3 Three Basic Tissues ectoderm mesoderm endoderm muscle layers mesoderm epidermis ectoderm ciliated epidermis ectoderm parenchyma mesoderm pharynx nerve cord ectoderm gut endoderm General Features of Flatworms • Cephalized – Sensory organs and ganglia concentrated in head – Suitable for directional locomotion • Acoelomate – no fluid-filled body cavity between gut and body wall, instead, “parenchyma” tissue • Epidermis of living, often ciliated cells Typical Organs and Organ Systems compare Hickman Fig. 14-6 cephalic ganglion ovary nerve cord yolk glands auricle seminal receptacle penis eye protonephridia gut testes pharynx seminal vesicle Platyhelminthes Classification • Class Turbellaria – Planarians and other free-living flatworms – Benthic, planktonic – Marine, freshwater, terrestrial • Classes Trematoda and Cestoda – next lecture • Class Monogenea (fish parasites) Some Turbellarians triclad planarian in moist or aquatic habitats protrusible pharynx terrestrial flatworm polyclad flatworm on coral reef Fig 14.6C Feeding and Digestion • predators or saprophages • branched, incomplete gut – Serves as circulatory system in largest ones – Lacking in tapeworms and smaller turbellarians – Muscular, sometimes protrusible pharynx Reproduction • Sexual reproduction: – mostly hermaphroditic (= monecious) – good, since any two individuals can mate • Reproduce asexually by transverse fission microturbellarians, forming asexual chains Review of Organ Systems compare Hickman Fig. 14-6 cephalic ganglion ovary nerve cord yolk glands auricle seminal receptacle penis eye protonephridia gut testes pharynx seminal vesicle Nervous and Excretory Systems • nervous system – ganglia in head – ventral nerve cords – sense organs for light and chemicals • excretory + osmoregulatory system – protonephridia: flame cells and tube cells • flagella and collar resemble collar cells Review of Organ Systems compare Hickman Fig. 14-6 cephalic ganglion ovary nerve cord yolk glands auricle seminal receptacle penis eye protonephridia gut testes pharynx seminal vesicle Parasitic Platyhelminthes Flukes (Trematoda) And Tapeworms (Cestoda) Parasitic Relationships • Parasites steal food from host – usually not lethal, but weaken or reduce growth or reproduction of host • Parasites have great reproductive capacity – Chances of transmission to another host are small under normal circumstances • Life cycles are complex – Larval stages in other hosts – Asexual reproduction in larval stage Class Trematoda • internal parasites of vertebrates – Intestine, liver, blood vessels, bladder, etc. • epidermis is not ciliated, but absorptive – Consists of syncytial cells • complex life cycles – Larval stages in other hosts – Asexual reproduction in sporocyst and redia stages Trematoda Anatomy compare Hickman Fig. 14-7 Contrasts With Turbellaria - anterior mouth with sucker - another, ventral sucker larger uterus (greater fecundity) food-absorbing epidermis reduced sensory organs Syncytial Epidermis of Flukes Hickman Fig. 14-17 adults (unusual because diecious) eggs Schistosome Fluke Life Cycle Fig. 14.13 cercaria Redia (not shown) miracidium sporocyst reproduces asexually Tapeworms - Class Cestoda • live in vertebrate intestines – up to 7 m long, full length of human small intestine • absorb digested food through epidermis – mucus and acidic compounds defend against host enzymes • live without oxygen – necessary , but very inefficient- use much food Tapeworm Adult Anatomy compare Hickman Fig. 14-19 Scolex -anchors worm, buds asexually Gravid Proglottids break off and release eggs testes uterus gonopore ovaries Proglottid reproduces sexually in person’s stomach, larva emerges from cyst person eats undercooked beef encysted larva occurs in ”measly” beef Life Cycle of the Beef Tapeworm final host gravid proglottids drop off and exit with feces egg hatches and migrates into cow’s muscles cow ingests egg alternate host resistant egg is released on grass Like Hickman 14-9 Tapeworms and Health • human tapeworm infections are common – compete for food in intestine – abundant before effects are noticeable • dog tapeworm can harm people when we become intermediate hosts – requires oral exposure to dog feces – larvae move from intestine to liver or muscles and form large cysts Cerebratulus An example of spiral clevage from the Phylum Nemertea Phylum Nemertea • • • • • Ribbon worms Mostly marine, known for their proboscis Excellent example of spiral clevage Similar to platyhelmithes but mostly dioecious Pilidium larvae Acoelomate,bilateral Cerebratulus Proboscius everted from Rhyncocoel Feeding and Defense Rhynchocoel an extendable proboscis that lies in a sheath. muscular pressure on fluid filled cavity everts muscles retract it Cerebratulus Locomotion use a combination of musculature and cilia Can use stylet (from proboscius) to attach and draw body forward Circulation closed system, pumping achieved by muscular contraction Cerebratulus Basidiodiscus Nervous system brain connected to a series of longitudinal nerves that extend posteriorly ocelli, tactile papillae, sensory pits and grooves Cerebratulus Reproduction and Development Dioecious, discharging both sperm and eggs into the water. Determinate, spiral clevage Pilidium larvae dorsal spike of fused cilia Chapter 14 Integrated Principles of Zoology Eleventh Edition Hickman/Roberts/Larson (c) The McGraw-Hill Companies, Inc. The End.