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 epidermis ectoderm parenchyma mesoderm muscle layers mesoderm ciliated epidermis ectoderm 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 seminal receptacle auricle 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 seminal receptacle auricle 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 seminal receptacle auricle 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) Schistosome Fluke Life eggs Cycle Fig. 14.13 cercaria miracidium Redia (not shown) 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 ovaries gonopore Proglottid - reproduces sexually
person eats undercooked beef in person s stomach, larva emerges from cyst Life Cycle encysted larva occurs in measly beef final host of the Beef Tapeworm gravid proglottids drop off and exit with feces egg hatches and migrates into cow s muscles cow ingests egg resistant egg is released on grass alternate host 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.