DOCSLIB.ORG

Chapter 29: Echinoderms and Invertebrate Chordates

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Chapter 29: Echinoderms and Invertebrate Chordates 0762 C29CO BDOL-829900 8/4/04 10:12 PM Page 762 Echinoderms and Invertebrate Chordates What You’ll Learn ■ You will compare and contrast the adaptations of echinoderms. ■ You will distinguish the fea- tures of chordates by examin- ing invertebrate chordates. Why It’s Important By studying how echinoderms and invertebrate chordates func- tion, you will enhance your understanding of the begin- nings of vertebrate evolution. Understanding the Photo Echinoderms obtain food by a variety of methods. They can be carnivores, herbivores, scav- engers, or filter feeders. These sea stars are carnivorous echino- derms. They extend the stomach from the mouth and engulf mussels, filter-feeding mollusks. Visit ca.bdol.glencoe.com to • study the entire chapter online • access Web Links for more information and activities on echinoderms and invertebrate chordates • review content with the Interactive Tutor and self- check quizzes 762 David Wrobel/Visuals Unlimited 0763-0769 C29S1 BDOL-829900 8/4/04 8:54 PM Page 763 Echinoderms 29.1 SECTION PREVIEW Objectives Echinoderms Make the following Foldable to compare and Compare similarities and contrast the characteristics of sea urchins and brittle stars. differences among the classes of echinoderms. STEP 1 Fold one sheet STEP 2 Fold into thirds. Interpret the evidence of paper lengthwise. biologists have for deter- mining that echinoderms are close relatives of chordates. Review Vocabulary STEP 3 STEP 4 endoskeleton: internal Unfold and draw over- Label the ovals skeleton of vertebrates lapping ovals. Cut the top sheet along as shown. and some invertebrates the folds. (p. 684) Sea Both Brittle New Vocabulary Urchins Stars ray pedicellaria water vascular system Construct a Venn Diagram As you read Chapter 29, list the characteristics madreporite unique to sea urchins under the left tab, those unique to brittle stars under the tube foot right tab, and those characteristics common to both under the middle tab. ampulla What is an echinoderm? Members of the phylum Echinodermata have a number of unusual char- acteristics that easily distinguish them from members of any other animal phylum. Echinoderms move by means of hundreds of hydraulic, suction- cup-tipped appendages and have skin covered with tiny, jawlike pincers. echinoderm from Echinoderms (ih KI nuh durmz) are found in all the oceans of the world. the Greek words echinos, meaning Echinoderms have endoskeletons “spiny,” and derma, meaning “skin”; If you were to examine the skin of several different echinoderms, you Echinoderms are would find that they all have a hard, spiny, or bumpy endoskeleton cov- spiny-skinned animals. ered by a thin epidermis. The long, pointed spines on a sea urchin are pedicellariae from obvious. Sea stars, sometimes called starfishes, may not appear spiny at the Latin word first glance, but a close look reveals that their long, tapering arms, called pediculus, meaning rays, are covered with short, rounded spines. The spiny skin of a sea “little foot”; Pedicellariae cucumber consists of soft tissue embedded with small, platelike structures resemble little feet. that barely resemble spines. The endoskeleton of all echinoderms is made primarily of calcium carbonate, the compound that makes up limestone. Some of the spines found on sea stars and sea urchins have become modified into pincerlike appendages called pedicellariae (PEH dih sih LAHR ee ay). An echinoderm uses its jawlike pedicellariae for protection and for cleaning the surface of its body. You can examine these structures in the MiniLab on the following page. 29.1 ECHINODERMS 763 0763-0769 C29S1 BDOL-829900 8/4/04 8:55 PM Page 764 Echinoderms have radial symmetry You may remember that radial Observe and Infer symmetry is an advantage to animals Examining Pedicellariae Echino- that are stationary or move slowly. derms have tiny pincers on their Radial symmetry enables these ani- skin called pedicellariae. mals to sense potential food, preda- tors, and other aspects of their Procedure environment from all directions. ! Observe a slide of sea star Observe the radial symmetry, as well pedicellariae under low- as the various sizes and shapes of power magnification. spines, of each echinoderm pictured CAUTION: Use caution when in Figure 29.1. working with a microscope Pedicellariae and slides. The water vascular system @ Record the general appearance of one pedicellaria. What does it look like? Another characteristic unique to # Make a diagram of one pedicellaria under low-power echinoderms is the water vascular sys- magnification. tem that enables them to move, exchange gases, capture food, and Analysis excrete wastes. The water vascular 1. Observe Describe the general appearance of one system is a hydraulic system that pedicellaria. operates under water pressure. Water 2. Infer What is the function of this structure? enters and leaves the water vascular 3. Explain How does the structure of pedicellariae assist system of a sea star through the in their function? madreporite (mah druh POHR ite), a sievelike, disk-shaped opening on the upper surface of the echinoderm’s body. This disk functions like the strainer that fits into a sink drain and Figure 29.1 keeps large particles out of the pipes. All echinoderms have radial symmetry as adults and an endoskele- ton composed primarily of calcium carbonate. Explain How does radial symmetry benefit an animal that cannot move fast? A A living sand dollar has an endoskeleton composed of flattened plates that are fused into a rigid framework. B A sea lily’s feathery rays are composed of calcified skeletal plates covered with an epidermis. 764 (t)Kenneth Read/Tom Stack & Associates, (bl)Scott Johnson/Animals Animals, (br)Norbert Wu/Peter Arnold, Inc. 0763-0769 C29S1 BDOL-829900 8/4/04 8:56 PM Page 765 Look at the close-up of the under- side of a sea star in Figure 29.2. You can see that tube feet run along a groove on the underside of each ray. Tube feet are hollow, thin-walled tubes that end in a suction cup. Tube feet look somewhat like miniature droppers. The round, muscular struc- ture called the ampulla (AM pew lah) Figure 29.2 works something like the bulb of a information to the animal. Echino- Tube feet enable sea dropper. The end of a tube foot works stars and other echino- derms have cells that detect light and like a tiny suction cup. You can find derms to creep along touch, but most do not have sensory out how tube feet help a sea star eat the ocean bottom or to organs. Sea stars are an exception. A sea by looking at Figure 29.4 on the next pry open the shells of star’s body consists of long, tapering bivalves. Infer What page. Each tube foot works indepen- rays that extend from the animal’s cen- causes the suction a dently of the others, and the animal tral disk. A sensory organ known as an sea star uses to pry moves along slowly by alternately open shells? eyespot and consisting of a cluster of pushing out and pulling in its tube light-detecting cells is located at the tip feet. You can learn more about the of each arm, on the underside. Eyespots operation of the water vascular sys- enable sea stars to detect the intensity of tem in the Connection to Physics at the light. Most sea stars move toward light. end of this chapter. Sea stars also have chemical receptors Tube feet also function in gas on their tube feet. When a sea star exchange and excretion. Gases are detects a chemical signal from a prey exchanged and wastes are eliminated animal, it moves in the direction of the by diffusion through the thin walls of arm receiving the strongest signal. the tube feet. Figure 29.3 Echinoderms have varied Echinoderms have bilaterally The larval stage of nutrition symmetrical larvae echinoderms is bilat- eral, even though the All echinoderms have a mouth, If you examine the larval stages of adult stage has radial stomach, and intestines, but their echinoderms, you will find that they symmetry. Explain methods of obtaining food vary. Sea have bilateral symmetry. The ciliated What does this characteristic show stars are carnivorous and prey on larva that develops from the fertilized about echinoderms? worms or on mollusks such as clams. egg of an echinoderm is shown in Most sea urchins are herbivores and Figure 29.3. Through metamor- graze on algae. Brittle stars, sea lilies, phosis, the free-swimming larvae and sea cucumbers feed on dead and make dramatic changes in both decaying matter that drifts down to body parts and in symmetry. the ocean floor. Echinoderms are Echinoderms have a simple deuterostomes nervous system Recall that most invertebrates Echinoderms have no head or brain, show protostome development. but they do have a central nerve ring Echinoderms are deuterostomes. that surrounds the mouth. Nerves This pattern of development extend from the nerve ring down each indicates a close relationship ray. Each radial nerve then branches to chordates, which are also into a nerve net that provides sensory deuterostomes. Color-enhanced LM Magnification: 125ϫ 29.1 ECHINODERMS 765 (t)Norbert Wu, (b)Cabisco/Visuals Unlimited 0763-0769 C29S1 BDOL-829900 8/4/04 8:56 PM Page 766 A Sea Star Figure 29.4 If you ever tried to pull a sea star from a rock where it is attached, you would be impressed by how unyielding and rigid the animal seems to be. Yet at other times, the animal shows great flexibility, such as when it rights itself after being turned upside down. The rigidity or flexibility of a sea star is due to its endoskeleton. Critical Thinking How is radial symmetry useful to a sea star? A Endoskeleton A sea star can quickly Blood sea star change from a rigid structure to a flexible one because it has an endoskeleton in the form of calcium carbonate plates just under its epidermis.
Load more

Recommended publications
  • "Lophophorates" Brachiopoda Echinodermata Asterozoa
    Deuterostomes Bryozoa Phoronida "lophophorates" Brachiopoda Echinodermata Asterozoa Stelleroidea Asteroidea Ophiuroidea Echinozoa Holothuroidea Echinoidea Crinozoa Crinoidea Chaetognatha (arrow worms) Hemichordata (acorn worms) Chordata Urochordata (sea squirt) Cephalochordata (amphioxoius) Vertebrata PHYLUM CHAETOGNATHA (70 spp) Arrow worms Fossils from the Cambrium Carnivorous - link between small phytoplankton and larger zooplankton (1-15 cm long) Pharyngeal gill pores No notochord Peculiar origin for mesoderm (not strictly enterocoelous) Uncertain relationship with echinoderms PHYLUM HEMICHORDATA (120 spp) Acorn worms Pharyngeal gill pores No notochord (Stomochord cartilaginous and once thought homologous w/notochord) Tornaria larvae very similar to asteroidea Bipinnaria larvae CLASS ENTEROPNEUSTA (acorn worms) Marine, bottom dwellers CLASS PTEROBRANCHIA Colonial, sessile, filter feeding, tube dwellers Small (1-2 mm), "U" shaped gut, no gill slits PHYLUM CHORDATA Body segmented Axial notochord Dorsal hollow nerve chord Paired gill slits Post anal tail SUBPHYLUM UROCHORDATA Marine, sessile Body covered in a cellulose tunic ("Tunicates") Filter feeder (» 200 L/day) - perforated pharnx adapted for filtering & repiration Pharyngeal basket contractable - squirts water when exposed at low tide Hermaphrodites Tadpole larvae w/chordate characteristics (neoteny) CLASS ASCIDIACEA (sea squirt/tunicate - sessile) No excretory system Open circulatory system (can reverse blood flow) Endostyle - (homologous to thyroid of vertebrates) ciliated groove
    [Show full text]
  • Evidence for Selection on a Chordate Histocompatibility Locus
    ORIGINAL ARTICLE doi:10.1111/j.1558-5646.2012.01787.x EVIDENCE FOR SELECTION ON A CHORDATE HISTOCOMPATIBILITY LOCUS Marie L. Nydam,1,2,3 Alyssa A. Taylor,3 and Anthony W. De Tomaso3 1Division of Science and Mathematics, Centre College, Danville, Kentucky 40422 2E-mail: [email protected] 3Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, California 93106 Received June 7, 2011 Accepted July 31, 2012 Allorecognition is the ability of an organism to differentiate self or close relatives from unrelated individuals. The best known applications of allorecognition are the prevention of inbreeding in hermaphroditic species (e.g., the self-incompatibility [SI] systems in plants), the vertebrate immune response to foreign antigens mediated by MHC loci, and somatic fusion, where two genetically independent individuals physically join to become a chimera. In the few model systems where the loci governing allorecognition outcomes have been identified, the corresponding proteins have exhibited exceptional polymorphism. But information about the evolution of this polymorphism outside MHC is limited. We address this subject in the ascidian Botryllus schlosseri,where allorecognition outcomes are determined by a single locus, called FuHC (Fusion/HistoCompatibility). Molecular variation in FuHC is distributed almost entirely within populations, with very little evidence for differentiation among different populations. Mutation plays a larger role than recombination in the creation of FuHC polymorphism. A selection statistic, neutrality tests, and distribution of variation within and among different populations all provide evidence for selection acting on FuHC, but are not in agreement as to whether the selection is balancing or directional.
    [Show full text]
  • (= Amphioxus) Branchiostoma Floridae
    MARINE ECOLOGY PROGRESS SERIES Vol. 130: 71-84,1996 Published January 11 Mar Ecol Prog Ser Larval settlement, post-settlement growth and secondary production of the Florida lancelet (= amphioxus) Branchiostoma floridae M. D. Stokes* Marine Biology Research Division, Scripps Institution of Oceanography, La Jolla, California 92093-0202, USA ABSTRACT A population of Branch~ostomaflondae in Tampa Bay, Flonda, USA was sieved from the substratum frequently (often daily) from June 1992 through September 1994 Body lengths were mea- sured for 54264 luvenlle and adult lancelets The breedlng season lasted each year from early May through early September and newly metamorphosed lancelets settled as luveniles from late May through mid October, dunng this period of the year dlstinct settlements occurred approxmately every 1 to 3 wk Post-settlement growth was followed as changes in modal length on size-frequency histo- grams Changes in cohort growth over this peliod were compared to several different simple and seasonally oscillating growth models The von Bertalanffy functlon in smple and oscillating forms provided the best estmates of lancelet growth The lancelets grew in summer (almost 0 5 mm d-' in recently settled luveniles), but growth slowed and almost ceased durlng wlnter B flondae can llve at least 2 yr and can reach a maxlmum length of 58 mm The maximal secondary productlon was 61 53 g m-' yrrl (ash-free dry welght) and the productlon to biomass ratio was 11 64 Population den- sities at the study site ranged from about 100 to 1200 lancelets m ' KEY WORDS: Lancelet . Amphioxus . Branchiostorna flondae . Growth . Production . Breeding season .
    [Show full text]
  • The Origins of Chordate Larvae Donald I Williamson* Marine Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom
    lopmen ve ta e l B Williamson, Cell Dev Biol 2012, 1:1 D io & l l o l g DOI: 10.4172/2168-9296.1000101 e y C Cell & Developmental Biology ISSN: 2168-9296 Research Article Open Access The Origins of Chordate Larvae Donald I Williamson* Marine Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom Abstract The larval transfer hypothesis states that larvae originated as adults in other taxa and their genomes were transferred by hybridization. It contests the view that larvae and corresponding adults evolved from common ancestors. The present paper reviews the life histories of chordates, and it interprets them in terms of the larval transfer hypothesis. It is the first paper to apply the hypothesis to craniates. I claim that the larvae of tunicates were acquired from adult larvaceans, the larvae of lampreys from adult cephalochordates, the larvae of lungfishes from adult craniate tadpoles, and the larvae of ray-finned fishes from other ray-finned fishes in different families. The occurrence of larvae in some fishes and their absence in others is correlated with reproductive behavior. Adult amphibians evolved from adult fishes, but larval amphibians did not evolve from either adult or larval fishes. I submit that [1] early amphibians had no larvae and that several families of urodeles and one subfamily of anurans have retained direct development, [2] the tadpole larvae of anurans and urodeles were acquired separately from different Mesozoic adult tadpoles, and [3] the post-tadpole larvae of salamanders were acquired from adults of other urodeles. Reptiles, birds and mammals probably evolved from amphibians that never acquired larvae.
    [Show full text]
  • Abstract Introduction
    Marine and Freshwater Miscellanea III KEY TRAITS OF AMPHIOXUS SPECIES (CEPHALOCHORDATA) AND THE GOLT1 Daniel Pauly and Elaine Chu Sea Around Us, Institute for the Oceans and Fisheries University of British Columbia, Vancouver, B.C, Canada Email: [email protected] Abstract Major biological traits of amphioxus species (Cephalochordata) are presented with emphasis on the size reached by their 32 valid species in the genera Asymmetron (2 spp.), Branchiostoma (25 spp.), and Epigonichthys (5 spp.) and on related features, i.e., growth parameters and size at first maturity. Overall, these traits combined with features of their respiration, suggest that the cephalochordates conform to the Gill Oxygen Limitation Theory (GOLT), which relates the growth performance of water-breathing ectotherms to the surface area of their respiratory organ(s). Introduction The small fish-like animals know as ‘lancelet‘ or ‘amphioxius’ belong the subphylum Cephalochordata, which is either a sister group, or related to the ancestor of the vertebrate animals (see Garcia-Fernàndez and Benito-Gutierrez 2008). The cephalochordates consist of 3 families (the Asymmetronidae, Epigonichthyidae and Branchiostomidae), with one genus each, Asymmetron (2 spp.), Branchiostoma (24 spp.) and Epigonichthys (6 spp.), as detailed in Table 1 and SeaLifeBase (www.sealifebase.org). This contribution is to assemble some of the basic biological traits of lancelets (Figure 1), notably the maximum size each of their 34 species can reach, which is easily their most important attribute, though it is often ignored (Haldane 1926). Finally, reported lengths at first maturity of cephalochordates were related to the corresponding, population-specific maximum length, to test whether these animals mature as predicted by the Gill- Oxygen Limitation Theory (GOLT; see Pauly 2021a, 2021b).
    [Show full text]
  • Development of the Annelid Axochord: Insights Into Notochord Evolution Antonella Lauri Et Al
    RESEARCH | REPORTS ORIGIN OF NOTOCHORD by double WMISH (Fig. 2, F to L). Although none of the genes were exclusively expressed in the annelid mesodermal midline, their combined Development of the annelid coexpression was unique to these cells (implying that mesodermal midline in annelids and chor- damesoderm in vertebrates are more similar to axochord: Insights into each other than to any other tissue). It is unlikely that the molecular similarity between annelid notochord evolution and vertebrate mesodermal midline is due to in- dependent co-option of a conserved gene cas- Antonella Lauri,1*† Thibaut Brunet,1* Mette Handberg-Thorsager,1,2‡ sette, because this would require either that this Antje H.L. Fischer,1§ Oleg Simakov,1 Patrick R. H. Steinmetz,1‖ Raju Tomer,1,2¶ cassette was active elsewhere in the body (which Philipp J. Keller,2 Detlev Arendt1,3# is not the case) or that multiple identical inde- pendent events of co-option occurred (which is The origin of chordates has been debated for more than a century, with one key issue being unparsimonious). As in vertebrates, the meso- the emergence of the notochord. In vertebrates, the notochord develops by convergence dermal midline resembles the neuroectodermal and extension of the chordamesoderm, a population of midline cells of unique molecular midline, which expresses foxD, foxA, netrin, slit, identity. We identify a population of mesodermal cells in a developing invertebrate, the marine and noggin (figs. S6 and S7) but not brachyury or annelid Platynereis dumerilii, that converges and extends toward the midline and expresses a twist. However, unlike in chicken (10), the an- notochord-specific combination of genes.
    [Show full text]
  • Biology of Echinoderms
    Echinoderms Branches on the Tree of Life Programs ECHINODERMS Written and photographed by David Denning and Bruce Russell Produced by BioMEDIA ASSOCIATES ©2005 - Running time 16 minutes. Order Toll Free (877) 661-5355 Order by FAX (843) 470-0237 The Phylum Echinodermata consists of about 6,000 living species, all of which are marine. This video program compares the five major classes of living echinoderms in terms of basic functional biology, evolution and ecology using living examples, animations and a few fossil species. Detailed micro- and macro- photography reveal special adaptations of echinoderms and their larval biology. (THUMBNAIL IMAGES IN THIS GUIDE ARE FROM THE VIDEO PROGRAM) Summary of the Program: Introduction - Characteristics of the Class Echinoidea phylum. spine adaptations, pedicellaria, Aristotle‘s lantern, sand dollars, urchin development, Class Asteroidea gastrulation, settlement skeleton, water vascular system, tube feet function, feeding, digestion, Class Holuthuroidea spawning, larval development, diversity symmetry, water vascular system, ossicles, defensive mechanisms, diversity, ecology Class Ophiuroidea regeneration, feeding, diversity Class Crinoidea – Topics ecology, diversity, fossil echinoderms © BioMEDIA ASSOCIATES (1 of 7) Echinoderms ... ... The characteristics that distinguish Phylum Echinodermata are: radial symmetry, internal skeleton, and water-vascular system. Echinoderms appear to be quite different than other ‘advanced’ animal phyla, having radial (spokes of a wheel) symmetry as adults, rather than bilateral (worm-like) symmetry as in other triploblastic (three cell-layer) animals. Viewers of this program will observe that echinoderm radial symmetry is secondary; echinoderms begin as bilateral free-swimming larvae and become radial at the time of metamorphosis. Also, in one echinoderm group, the sea cucumbers, partial bilateral symmetry is retained in the adult stages -- sea cucumbers are somewhat worm–like.
    [Show full text]
  • Origin of Chordates Part-I
    ORIGIN OF CHORDATES Evolution of chordate was one of the most important event in the history of chordate as it was the beginning of evolution of more advanced chordates like bird and mammals. It is the story of origin from a primitive invertebrate like creatures to early chordates. Though first fossil of the first vertebrate the ostrachoderm was discovered from the Ordovician period but it might have originated in late Cambrian period. As early chordates were soft bodied, their fossil records are not preserved. Hence, to trace their ancestry, we have to find out the similarity among different deuterostomes to trace the origin of chordates. Some structural features shared by them such as bilateral symmetry, antero-posterior body axis, triploblastic coelomate condition, etc., may he because of their common ancestry. TIME OF ORIGIN: Late Cambrian period PLACE OF ORIGIN: Fresh water THEORIES OF INVERTEBRATE ANCESTRY OF CHORDATES Several theories have been put forwarded to explain the origin of chordates either directly from some invertebrate group or through the intervention of some protochordate. Almost every invertebrate phylum—Coelenterata, Nemertean, Phoronida, Annelids, Arthropods and Echinodermatashas been suggested. But these theories are far from being satisfactory and convincing and have only a historical value. Only the echinoderm theory has received some acceptance. DIVISION OF BILATERIA The Bilateria is divided into two major divisions (1) Protostomia and (2) Deuterostornia. This division is based on the differences in embryonic and larval developments. Protostomia includes from Annelida to Arthropoda while deuterostomia includes Echinodermata, Pogonophora and Chordate. DEUTEROSTOME LINE OF CHORDATE EVOLUTION Following common features of all Deuterostomes suggests strong evidence of a closer evolutionary relationship between the three principal deuterostome phyla – Echinodermata, Hemichordata and Chordata.
    [Show full text]
  • A New Species of the Calcareous Sponge Genus Leuclathrina (Calcarea: Calcinea: Clathrinida) from the Maldives
    Zootaxa 4382 (1): 147–158 ISSN 1175-5326 (print edition) http://www.mapress.com/j/zt/ Article ZOOTAXA Copyright © 2018 Magnolia Press ISSN 1175-5334 (online edition) https://doi.org/10.11646/zootaxa.4382.1.5 http://zoobank.org/urn:lsid:zoobank.org:pub:B222C2D8-82FB-414C-A88F-44A12A837A21 A new species of the calcareous sponge genus Leuclathrina (Calcarea: Calcinea: Clathrinida) from the Maldives OLIVER VOIGT1,5, BERNHARD RUTHENSTEINER2, LAURA LEIVA1, BENEDETTA FRADUSCO1 & GERT WÖRHEIDE1,3,4 1Department of Earth and Environmental Sciences, Palaeontology and Geobiology, Ludwig-Maximilians-Universität München, Rich- ard-Wagner-Str. 10, 80333 München, Germany 2 SNSB - Zoologische Staatssammlung München, Sektion Evertebrata varia, Münchhausenstr. 21, 81247 München, Germany 3 GeoBio-Center, Ludwig-Maximilians-Universität München, Richard-Wagner-Str. 10, 80333 München, Germany 4SNSB - Bayerische Staatssammlung für Paläontologie und Geologie, Richard-Wagner-Str. 10, 80333 München, Germany 5Corresponding author. E-mail: [email protected], Tel.: +49 (0) 89 2180 6635; Fax: +49 (0) 89 2180 6601 Abstract The diversity and phylogenetic relationships of calcareous sponges are still not completely understood. Recent integrative approaches combined analyses of DNA and morphological observations. Such studies resulted in severe taxonomic revi- sions within the subclass Calcinea and provided the foundation for a phylogenetically meaningful classification. However, several genera are missing from DNA phylogenies and their relationship to other Calcinea remain uncertain. One of these genera is Leuclathrina (family Leucaltidae). We here describe a new species from the Maldives, Leuclathrina translucida sp. nov., which is only the second species of the genus. Like the type species Leuclathrina asconoides, the new species has a leuconoid aquiferous system and lacks a specialized choanoskeleton.
    [Show full text]
  • 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
    [Show full text]
  • Sponges Cnidarians Chordates Brachiopods Annelids Molluscs Ediacaran Arthropods 635 Cambrian PALEOZOIC PROTEROZOIC 605 Time (Mil
    © 2014 Pearson Education, Inc. 1 Sponges Cnidarians Echinoderms Chordates Brachiopods Annelids Molluscs Arthropods PROTEROZOIC PALEOZOIC Ediacaran Cambrian 635 605 575 545 515 485 0 Time (millions of years age) © 2014 Pearson Education, Inc. 2 Food particles in mucus Choanocyte Collar Flagellum Choanocyte Phagocytosis of Amoebocyte food particles Pores Spicules Water flow Amoebocytes Azure vase sponge (Callyspongia plicifera) © 2014 Pearson Education, Inc. 3 (a) Hydrozoa (b) Scyphozoa (c) Anthozoa © 2014 Pearson Education, Inc. 4 15 µm 75 µm (a) Valeria (800 mya): (b) Spiny acritarch roughly spherical, no (575 mya): about five structural defenses, times larger than soft-bodied Valeria and covered in hard spines © 2014 Pearson Education, Inc. 5 (a) Radial symmetry (b) Bilateral symmetry © 2014 Pearson Education, Inc. 6 Body cavity Body covering (from ectoderm) Tissue layer lining body cavity and suspending Digestive tract internal organs (from endoderm) (from mesoderm) © 2014 Pearson Education, Inc. 7 Porifera Metazoa Ctenophora ANCESTRAL Eumetazoa PROTIST Cnidaria Deuterostomia Hemichordata 770 million Echinodermata years ago 680 million Chordata years ago Lophotrochozoa Lophotrochozoa Platyhelminthes Bilateria Rotifera Ectoprocta Brachiopoda 670 million years ago Mollusca Ecdysozoa Annelida Nematoda Arthropoda © 2014 Pearson Education, Inc. 8 © 2014 Pearson Education, Inc. 9 Notochord Dorsal, hollow nerve cord Muscle segments Mouth Anus Post-anal tail Pharyngeal slits or clefts © 2014 Pearson Education, Inc. 10 (a) Lancelet (b) Tunicate
    [Show full text]
  • New Records of the Lancelet Branchiostoma Lanceolatum in Scottish Waters
    The Glasgow Naturalist (online 2019) Volume 27, Part 1 New records of the lancelet Branchiostoma lanceolatum in Scottish waters M. O’Reilly1, S. Nowacki1, M. Baptie1, E. Gerrie1 & M. MacKenzie2 1Scottish Environment Protection Agency, Angus Smith Building, 6 Parklands Avenue, Eurocentral, Holytown, North Lanarkshire ML1 4WQ 2Scottish Environment Protection Agency, Graesser House, Fodderty Way, Dingwall IV15 9XB 1E-mail: [email protected] ABSTRACT New records of the lancelet Branchiostoma lanceolatum from Scottish waters are presented. Most of the records originate from sublittoral monitoring around fish farms from Orkney, Shetland, the Western Isles, the Isles of Skye and Mull, but also from a distillery discharge in the Firth of Clyde and a plankton survey in the Sea of the Hebrides. Lancelets were recovered in sediment grab samples from 6 - 60 m depth. Some recent accounts of intertidal lancelets are also cited. The lancelets appear to prefer coarser sediments and in the fish farm surveys were found predominantly at reference sites, away from the immediate influence of farm deposition. INTRODUCTION The lancelet Branchiostoma lanceolatum (Pallas, 1774) is an obscure, vaguely fish-like creature, up to 8 cm long, which lives buried in sand or coarse sediments in British seas. Its body is laterally compressed, pinkish white in colour, and pointed at both ends with a lance- like tail fin (Fig. 1). There are no paired fins, nor eyes, nor even a well-defined head, and it has only a small mouth surrounded by cirri, used to filter organic matter from the surrounding water. It has a dorsal notochord and segmented muscle blocks allowing it to swim in a sinusoidal fish-like manner, but no backbone, and it is therefore classified as an invertebrate (Barnes, 2015).
    [Show full text]