“Protochordates” & Origin of Vertebrates
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Flatworms Phylum Platyhelminthes
Flatworms Phylum Platyhelminthes The flatworms include more than 13,000 species of free-living and parasitic species.There are 3 classes of flat- worms, the planarians, flukes and tapeworms. General Physical Traits (Anatomy): Flatworms are bilaterally symmetrical. This means that they can only be cut them length-wise to produce two mirror-image halves. They have a distinct right and left half. This is differ- ent from radially symmetrical animals, like the anemones, which can be cut anywhere top to bottom to get two similar halves. Flatworms have 3 tissue layers, compared to the 2 layers in sponges and cnidarians (jellyfishes, anemones and corals). They also have only one opening for food to enter and waste to leave, like the sponges and cnidarians. This is called a “sac” body plan. Planarian (class Tubellaria) Habitat: They live mostly in saltwater (marine) habitats, but are also found in freshwater. Habits: They are free-living flatworms (not parasites). Physical Traits (Anatomy): Planarians are small - less than a centimeter long. They have a head, brain and sense organs. This is called “cephalization.” The sense organs – called eyespots – look like eyes and are sensitive to light changes, but are not like human eyes. They are made up of simple nerve cells that respond to stimuli, like light. When many nerve cells are gathered in one place, they are called a “ganglion,” so the two eyespots are actually ganglia. They also have points on either side of the head that look a bit like ears, called “sensory lobes” or auricles. They do not hear, but can sense food. -
Crossflow Filtration, Palatal Protrusions and Flow Reversals
W&M ScholarWorks Arts & Sciences Articles Arts and Sciences 2003 Feeding mechanisms in carp: crossflow filtration, palatal protrusions and flow er versals Todd Callan S. Laurie Sanderson College of William and Mary, [email protected] Follow this and additional works at: https://scholarworks.wm.edu/aspubs Part of the Marine Biology Commons Recommended Citation Callan, Todd and Sanderson, S. Laurie, Feeding mechanisms in carp: crossflow filtration, palatal protrusions and flow er versals (2003). Journal of Experimental Biology, 206, 883-892. doi: 10.1242/jeb.00195 This Article is brought to you for free and open access by the Arts and Sciences at W&M ScholarWorks. It has been accepted for inclusion in Arts & Sciences Articles by an authorized administrator of W&M ScholarWorks. For more information, please contact [email protected]. The Journal of Experimental Biology 206, 883-892 883 © 2003 The Company of Biologists Ltd doi:10.1242/jeb.00195 Feeding mechanisms in carp: crossflow filtration, palatal protrusions and flow reversals W. Todd Callan and S. Laurie Sanderson* Department of Biology, College of William and Mary, Williamsburg, VA 23187, USA *Author for correspondence (e-mail: [email protected]) Accepted 4 December 2002 Summary It has been hypothesized that, when engulfing food chemosensory function rather than a mechanical particle- mixed with inorganic particles during benthic feeding, sorting function. However, palatal protrusions did retain cyprinid fish use protrusions of tissue from the palatal large food particles while large inorganic particles were organ to retain the food particles while the inorganic spit anteriorly from the mouth. We also investigated particles are expelled from the opercular slits. -
Cyclostome Embryology and Early Evolutionary History of Vertebrates Kinya G
329 Cyclostome embryology and early evolutionary history of vertebrates Kinya G. Ota and Shigeru Kuratani1 Evolutionary Morphology Research Group, Center for Developmental Biology, RIKEN, Kobe, Japan Synopsis Modern agnathans include only two groups, the lampreys and the hagfish, that collectively comprise the group Cyclostomata. Although accumulating molecular data support the cyclostomes as a monophyletic group, there remain some unsettled questions regarding the evolutionary relationships of these animals in that they differ greatly in anatomical and developmental patterns and in their life histories. In this review, we summarize recent developmental data on the lamprey and discuss some questions related to vertebrate evolutionary development raised by the limited information available on hagfish embryos. Comparison of the lamprey and gnathostome developmental patterns suggests some plesiomorphic traits of vertebrates that would have already been established in the most recent common ancestor of the vertebrates. Understanding hagfish development will further clarify the, as yet, unrecognized ancestral characters that either the lampreys or hagfishes may have lost. We stress the immediate importance of hagfish embryology in the determination of the most plausible scenario for the early history of vertebrate evolution, by addressing questions about the origins of the neural crest, thyroid, and adenohypophysis as examples. Introduction—phylogeny and evolution anatomy (Janvier 1996; see subsequently), which In their basal position on the phylogenetic tree of the may, of course, simply reflect a secondary degen- vertebrates, the extant agnathans (the lampreys and erative condition in this animal. We should also the hagfish) are considered important for any under- remember that the lampreys also lack a cartilaginous standing of the history of the vertebrates (reviewed skeleton in the trunk in the larval stages, and even by Kuratani et al. -
Phylum Chordata
Phylum Chordata 48,000 species very diverse phylum but still more unity in major characteristics than in most other phyla most advanced phylum of animal kingdom one to which we belong along with fish, amphibians reptiles, birds and other mammals some of the largest or most massive animals true coelom 4 major identifying characteristics: 1. Notochord flexible rodlike structure enclosed by a fibrous sheath extends the length of the body in larva and/or adult provides basic support and serves as main axis for muscle attachments to permit “fishlike” undulatory movements first part of skeleton to form in embryo in primitive chordates the notochord persists through life Animals: Chordates & Introduction to Vertebrates; Ziser Lecture Notes, 2006 1 in most chordates the notochord is replaced by a vertebral column of bone remnants of the notochord remain as “intervertebral discs” 2. Dorsal tubular nerve cord in most invert groups; nerve cord is ventral & paired in chordates the nerve cord is a single dorsal hollow nerve cord front end usually enlarged to form brain 3. Pharyngeal (gill) slits slit-like opening sleading from throat to outside first evolved as a filter feeding apparatus still used by some to filter water for food in others as gills in some groups they are only found in embryo and lost as adults 4. endostyle or thyroid gland specific kind of tissue found only in chordates was originally part of the feeding apparatus endostyle secretes mucus and traps food inside the pharyngeal cavity eg. lamprey larva in most chordates the same tissue has become an endocrine Animals: Chordates & Introduction to Vertebrates; Ziser Lecture Notes, 2006 2 gland in the neck region that helps control metabolism 5. -
Animal Phylum Poster Porifera
Phylum PORIFERA CNIDARIA PLATYHELMINTHES ANNELIDA MOLLUSCA ECHINODERMATA ARTHROPODA CHORDATA Hexactinellida -- glass (siliceous) Anthozoa -- corals and sea Turbellaria -- free-living or symbiotic Polychaetes -- segmented Gastopods -- snails and slugs Asteroidea -- starfish Trilobitomorpha -- tribolites (extinct) Urochordata -- tunicates Groups sponges anemones flatworms (Dugusia) bristleworms Bivalves -- clams, scallops, mussels Echinoidea -- sea urchins, sand Chelicerata Cephalochordata -- lancelets (organisms studied in detail in Demospongia -- spongin or Hydrazoa -- hydras, some corals Trematoda -- flukes (parasitic) Oligochaetes -- earthworms (Lumbricus) Cephalopods -- squid, octopus, dollars Arachnida -- spiders, scorpions Mixini -- hagfish siliceous sponges Xiphosura -- horseshoe crabs Bio1AL are underlined) Cubozoa -- box jellyfish, sea wasps Cestoda -- tapeworms (parasitic) Hirudinea -- leeches nautilus Holothuroidea -- sea cucumbers Petromyzontida -- lamprey Mandibulata Calcarea -- calcareous sponges Scyphozoa -- jellyfish, sea nettles Monogenea -- parasitic flatworms Polyplacophora -- chitons Ophiuroidea -- brittle stars Chondrichtyes -- sharks, skates Crustacea -- crustaceans (shrimp, crayfish Scleropongiae -- coralline or Crinoidea -- sea lily, feather stars Actinipterygia -- ray-finned fish tropical reef sponges Hexapoda -- insects (cockroach, fruit fly) Sarcopterygia -- lobed-finned fish Myriapoda Amphibia (frog, newt) Chilopoda -- centipedes Diplopoda -- millipedes Reptilia (snake, turtle) Aves (chicken, hummingbird) Mammalia -
The Metamorphosis of the Endostyle (Thy- Roid Gland) of Ammocoetes Branchialis (Larval Land-Locked Petromyzon Marinus (Jordan) Or Petromy- Zon Dorsatus (Wilder) ).*I
THE METAMORPHOSIS OF THE ENDOSTYLE (THY- ROID GLAND) OF AMMOCOETES BRANCHIALIS (LARVAL LAND-LOCKED PETROMYZON MARINUS (JORDAN) OR PETROMY- ZON DORSATUS (WILDER) ).*I BY DAVID MARINE, M.D. (From the H. K. Cushing Laboratory of Experimental Medicine, Western Reserve University, Cleveland, and the Laboratory of Histology and Embryology, Cornell University, Ithaca.) PLATES 66 TO 70, INTRODUCTION. Wilhelm Mfil.ler in I873 homologized the endostyle, or hypo- branchial groove, of the Tunicate, Amphioxus, and the larval Petro- myzon with the thyroid gland of all higher chordates. Subse- quent investigations have served to strengthen this remarkable homology, which would have been impossible of demonstration but for the survival of a single ctass of vertebrates, the Cyclostomes, of which the Petromyzontid~e, or Lampreys, are the best known order. The lamprey embraces in its own life history both the fullest devel- opment of the endostyle mechanisms and the characteristic ductless * Received for publication, December 3o, I912. 1I am indebted to Professor B. F. Kingsbury for the privileges of his labora- tory and for helpful criticisms and suggestions. I wish also to thank Professor S. H. Gage for helpful suggestions, and Mr. J. F. Badertscher for aid in many technical problems. 2In addition to the ventral midline subpharyngeal glandular structure, or endostyle proper, there are accessory structures directly continuous with the endostyle epithelium developed in the pharyngeal mucosa that are believed to function as the path of conduction for the slime cord issuing from the orifice of the endostyle. This function has not, however, been observed in the Am- mocoetes and is based on reasoning by analogy from Giard's (Giard, A., Arch. -
Echinoderms for Dummies Colwyn Sleep Echinoderm Classification and Examples
ECHINODERMS FOR DUMMIES COLWYN SLEEP ECHINODERM CLASSIFICATION AND EXAMPLES What exactly is an Echinoderm? Echinoderms (or “Echinodermata”) are a group of animals which exist only in a marine (ocean) environment. Their name comes from the Greek word for "spiny skin". They inhabit a diverse range of marine habitats and are found on the sea floor from the intertidal zone to great ocean depths. In the following slides we will explore echinoderms and look into their body systems and structures more closely. A FEW EXAMPLES OF ECHINODERMS Sea star Kingdom: Animalia Phylum: Echinodermata Class: Asteroidea Feather Star Kingdom: Animalia Phylum: Echinodermata Subphylum: Crinozoa Class: Crinoidea Probably one of the best known echinoderms This lesser-known star, the feather star gains is the easily recognized sea star. The its name from its featherlike arms, which it echinoderm phylum contains many more uses to swim through the water. Like all species, in fact there are around 7000 known echinoderms, they are “Deuterostomes.” echinoderms. Later, we will investigate the This means that during their embryonic sea star and it’s classification as an development the first embryonic opening echinoderm in greater detail. becomes the anus and the second becomes the mouth. Because of this, biologists believe that echinoderms are more evolutionarily advanced than some of the other animals. A FEW MORE… Sea cucumber Kingdom: Animalia Phylum: Echinodermata Class: Holothuroidea Sea Urchin Kingdom: Animalia Phylum: Echinodermata Class: Echinoidea Related to Jabba the Hutt in appearance Like other echinoderms, the sea urchin has only, the sea cucumber is actually another radial symmetry. Its pointed spines offer example of an echinoderm. -
Introduction to Phylum Chordata
Unifying Themes 1. Chordate evolution is a history of innovations that is built upon major invertebrate traits •bilateral symmetry •cephalization •segmentation •coelom or "gut" tube 2. Chordate evolution is marked by physical and behavioral specializations • For example the forelimb of mammals has a wide range of structural variation, specialized by natural selection 3. Evolutionary innovations and specializations led to adaptive radiations - the development of a variety of forms from a single ancestral group Characteristics of the Chordates 1. Notochord 2. dorsal hollow nerve cord 3. pharyngeal gill slits 4. postanal tail 5. endostyle Characteristics of the Chordates Notochord •stiff, flexible rod, provides internal support • Remains throughout the life of most invertebrate chordates • only in the embryos of vertebrate chordates Characteristics of the Chordates cont. Dorsal Hollow Nerve Cord (Spinal Cord) •fluid-filled tube of nerve tissue, runs the length of the animal, just dorsal to the notochord • Present in chordates throughout embryonic and adult life Characteristics of the Chordates cont. Pharyngeal gill slits • Pairs of opening through the pharynx • Invertebrate chordates use them to filter food •In fishes the gill sits develop into true gills • In reptiles, birds, and mammals the gill slits are vestiges (occurring only in the embryo) Characteristics of the Chordates cont. Endostyle • mucous secreting structure found in the pharynx floor (traps small food particles) Characteristics of the Chordates cont. Postanal Tail • works with muscles (myomeres) & notochord to provide motility & stability • Aids in propulsion in nonvertebrates & fish but vestigial in later lineages SubPhylum Urochordata Ex: tunicates or sea squirts • Sessile as adults, but motile during the larval stages • Possess all 5 chordate characteristics as larvae • Settle head first on hard substrates and undergo a dramatic metamorphosis • tail, notochord, muscle segments, and nerve cord disappear SubPhylum Urochordata cont. -
Kclo4 Inhibits Thyroidal Activity in the Larval Lamprey Endostyle in Vitro
GENERAL AND COMPARATIVE ENDOCRINOLOGY General and Comparative Endocrinology 128 (2002) 214–223 www.academicpress.com KClO4 inhibits thyroidal activity in the larval lamprey endostyle in vitro Richard G. Manzon*,1 and John H. Youson Department of Zoology and Division of Life Sciences, University of Toronto at Scarborough, 1265 Military Trail, Toronto, Ont., Canada MIC 1A4 Accepted 5 July 2002 Abstract An in vitro experimental system was devised to assess the direct effects of the goitrogen, potassium perchlorate (KClO4), on ra- dioiodide uptake and organification by the larval lamprey endostyle. Organification refers to the incorporation of iodide into lamprey thyroglobulin (Tg). Histological and biochemical evidence indicated that endostyles were viable at the termination of a 4 h in vitro incubation. A single iodoprotein, designated as lamprey Tg, was identified in the endostylar homogenates by polyacrylamide gel electrophoresis and Western blotting. Lamprey Tg was immunoreactive with rabbit anti-human Tg serum and had an electrophoretic mobility similar to that of reduced porcine Tg. When KClO4 was added to the incubation medium, both iodide uptake and orga- nification by the endostyle were significantly reduced relative to controls as determined by gamma counting, and gel-autoradiography and densitometry, respectively. Western blotting showed that KClO4 significantly lowered the total amount of lamprey Tg in the endostyle. Based on the results of this in vitro investigation, we conclude that KClO4 acts directly on the larval lamprey endostyle to inhibit thyroidal activity. These data support a previous supposition from in vivo experimentation that KClO4 acts directly on the endostyle to suppress the synthesis of thyroxine and triiodothyronine, resulting in a decrease in the serum levels of these two hormones. -
Brain-Size Evolution and Sociality in Carnivora
Brain-size evolution and sociality in Carnivora John A. Finarellia,b,1 and John J. Flynnc aDepartment of Geological Sciences, University of Michigan, 2534 C.C. Little Building, 1100 North University Avenue, Ann Arbor, MI 48109; bMuseum of Paleontology, University of Michigan, 1529 Ruthven Museum, 1109 Geddes Road, Ann Arbor, MI 48109; and cDivision of Paleontology and Richard Gilder Graduate School, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 Edited by Alan Walker, Pennsylvania State University, University Park, PA, and approved April 22, 2009 (received for review February 16, 2009) Increased encephalization, or larger brain volume relative to body develop a comprehensive view of the evolutionary history of mass, is a repeated theme in vertebrate evolution. Here we present encephalization across 289 terrestrial species (including 125 an extensive sampling of relative brain sizes in fossil and extant extinct species) of Carnivora, providing an extensive sampling of taxa in the mammalian order Carnivora (cats, dogs, bears, weasels, fossil and living taxa for both major subclades: Caniformia and and their relatives). By using Akaike Information Criterion model Feliformia. selection and endocranial volume and body mass data for 289 species (including 125 fossil taxa), we document clade-specific Results evolutionary transformations in encephalization allometries. Akaike Information Criterion (AIC) model selection recovered These evolutionary transformations include multiple independent 4 optimal models (OM) within 2 log-likelihood units of the encephalization increases and decreases in addition to a remark- highest score (Table 1). There is broad agreement among the ably static basal Carnivora allometry that characterizes much of the OM with differences primarily in estimates of allometric slopes. -
The First Tunicate from the Early Cambrian of South China
The first tunicate from the Early Cambrian of South China Jun-Yuan Chen*, Di-Ying Huang, Qing-Qing Peng, Hui-Mei Chi, Xiu-Qiang Wang, and Man Feng Nanjing Institute of Geology and Palaeontology, Nanjing 210008, China Edited by Michael S. Levine, University of California, Berkeley, CA, and approved May 19, 2003 (received for review February 27, 2003) Here we report the discovery of eight specimens of an Early bilaterally symmetrical and club-shaped, and it is divided into Cambrian fossil tunicate Shankouclava near Kunming (South a barrel-shaped anterior part and an elongated, triangular, China). The tunicate identity of this organism is supported by the posterior part, which is called the ‘‘abdomen’’ (8–10). The presence of a large and perforated branchial basket, a sac-like anterior part, which occupies more than half the length of the peri-pharyngeal atrium, an oral siphon with apparent oral tenta- body, is dominated by a large pharyngeal basket, whose walls cles at the basal end of the siphonal chamber, perhaps a dorsal are formed by numerous transversely oriented rods interpreted atrial pore, and an elongated endostyle on the mid-ventral floor of as branchial bars. These bars are not quite straight, as the the pharynx. As in most modern tunicates, the gut is simple and anterior ones are weakly ϾϾϾ-shaped and the posterior ones U-shaped, and is connected with posterior end of the pharynx at slightly ϽϽϽ-shaped (Figs. 1 A, B, F, and H, and 2). The total one end and with an atrial siphon at the other, anal end. -
29 | Vertebrates 791 29 | VERTEBRATES
Chapter 29 | Vertebrates 791 29 | VERTEBRATES Figure 29.1 Examples of critically endangered vertebrate species include (a) the Siberian tiger (Panthera tigris), (b) the mountain gorilla (Gorilla beringei), and (c) the Philippine eagle (Pithecophega jefferyi). (credit a: modification of work by Dave Pape; credit b: modification of work by Dave Proffer; credit c: modification of work by "cuatrok77"/Flickr) Chapter Outline 29.1: Chordates 29.2: Fishes 29.3: AmphiBians 29.4: Reptiles 29.5: Birds 29.6: Mammals 29.7: The Evolution of Primates Introduction Vertebrates are among the most recognizable organisms of the animal kingdom. More than 62,000 vertebrate species have been identified. The vertebrate species now living represent only a small portion of the vertebrates that have existed. The best-known extinct vertebrates are the dinosaurs, a unique group of reptiles, which reached sizes not seen before or after in terrestrial animals. They were the dominant terrestrial animals for 150 million years, until they died out in a mass extinction near the end of the Cretaceous period. Although it is not known with certainty what caused their extinction, a great deal is known about the anatomy of the dinosaurs, given the preservation of skeletal elements in the fossil record. Currently, a number of vertebrate species face extinction primarily due to habitat loss and pollution. According to the International Union for the Conservation of Nature, more than 6,000 vertebrate species are classified as threatened. Amphibians and mammals are the classes with the greatest percentage of threatened species, with 29 percent of all amphibians and 21 percent of all mammals classified as threatened.