DOCSLIB.ORG

Class Myxini: Hagfishes

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Class Myxini: Hagfishes BLY 202 Superclass Agnatha: Jawless Fishes Objec'ves are to • Gain understanding of the characteris'cs of the jawless fishes • Have knowledge of the forms and func'ons of the two classes of the Superclass Agnatha • • Compare and contrast between Class Myxini and Class Cephalaspidomorphi Introduc'on • Living jawless fishes are represented by approximately 84 species • Myxini (hagfishes) with about 43 species • Cephalaspidomorphi (lampreys) with 41 species • Members of both groups lack jaws, internal ossificaon, scales, and paired fins, and both groups share pore-like gill openings and an eel-like body form • In other respects, the two groups are morphologically very different Characteriscs of Class Myxini • Body slender, eel-like, rounded, with naked skin containing slime glands • No paired appendages, no dorsal fin • Fibrous and car'laginous skeleton; notochord persistent • Bi'ng mouth with two rows of eversible teeth • Heart with sinus venosus, atrium, and ventricle; accessory hearts, aor'c arches in gill region • Five to 16 pairs of gills with a variable number of gill openings Characteriscs of Class Myxini cont… • Segmented mesonephric kidney; marine, body fluids isosmo'c with seawater • Diges've system without stomach; no spiral valve or cilia in intes'nal tract • Dorsal nerve cord with differen'ated brain; no cerebellum; 10 pairs of cranial nerves; dorsal and ventral nerve roots united • Sense organs of taste, smell, and hearing; eyes degenerate • Sexes separate (ovaries and testes in same individual but only one is func'onal); external fer'lizaon; large yolky eggs, no larval stage Class Myxini: Hagfishes • Hagfishes are an en'rely marine group that feeds on annelids, molluscs, crustaceans, and dead or dying fishes • They are not parasi'c like lampreys but are scavengers and predators • The best known in North America are the Atlan'c hagfish Myxine glunosa and the Pacific hagfish Eptatretus stou+ • Almost completely blind, hagfish is quickly aracted to food, especially dead or dying fishes, by its developed senses of smell and touch • The hagfish enters a dead or dying animal through an orifice or by digging inside. Using two toothed, keranized plates on the tongue that fold together in a pincer-like ac'on • The hagfish rasps away bits of flesh from its prey Class Myxini: Hagfishes cont… • Hagfishes are renowned for their ability to generate enormous quan''es of slime • If disturbed or roughly handled, the hagfish exudes a milky fluid from special glands posi'oned along the body • Unlike any other vertebrate, the body fluids of hagfishes are in osmo'c equilibrium with seawater, as in most marine invertebrates • Hagfishes have a low pressure circulatory system served by 3 accessory hearts in addi'on to the main heart posi'oned behind the gills • There is no larval stage Characteriscs of Class Cephalaspidomorphi • Body slender, eel-like, rounded with naked skin • One or two median fins, no paired appendages • Fibrous and car'laginous skeleton; notochord persistent • Sucker like oral disc and tongue with well-developed keranized teeth • Heart with sinus venosus, atrium, and ventricle; aor'c arches in gill region • Seven pairs of gills each with external gill opening Characteriscs of Class Cephalaspidomorphi cont… • Opisthonephric kidney; anadromous and fresh water; body fluids osmo'cally and ionically regulated • Dorsal nerve cord with differen'ated brain, small cerebellum present; 10 pairs cranial nerves; dorsal and ventral nerve roots separated • Diges've system without stomach; intes'ne with spiral fold • Sense organs of taste, smell, hearing; eyes well developed in adult; two pairs semicircular canals • Sexes separate; single gonad without duct; external fer'lizaon; long larval stage (ammocoete) Class Cephalaspidomorphi (Petromyzontes): Lampreys • All the lampreys of the Northern Hemisphere belong to the family Petromyzon'dae • The group name refers to the lamprey’s habit of grasping a stone with its mouth to hold posi'on in a current • There are 22 species of lampreys in North America • About half of these belong to the – nonparasi'c type; – the others are parasi'c • The genus Ichthyomyzon, includes three parasi'c and three nonparasi'c species. Class Cephalaspidomorphi (Petromyzontes): Lampreys cont… • All lampreys ascend freshwater streams to breed • The marine forms are anadromous, that is, they leave the sea where they spend their adult lives to swim up streams to spawn • At spawning, with the female aached to a rock to maintain her posi'on over the nest, the male aaches to the dorsal side of her head. As eggs are shed into the nest, the male fer'lizes them • The adults die soon aer spawning. The eggs hatch in about 2 weeks, releasing small larvae (ammocoetes) • Parasi'c lampreys either migrate to the sea, if marine • Or remain in fresh water, where they aach themselves by their sucker-like mouth to a fish and, with their sharp keranized teeth, rasp away the flesh and suck out body fluids. Class Cephalaspidomorphi (Petromyzontes): Lampreys cont • To promote the flow of blood, the lamprey injects an an'coagulant into the wound • When gorged, the lamprey releases its hold but leaves the fish with a large, gaping wound that is some'mes fatal • The parasi'c freshwater adults live 1 to 2 years before spawning and then die • The anadromous forms live 2 to 3 years • Nonparasi'c lampreys do not feed aer emerging as adults and their alimentary canal degenerates to a nonfunc'onal strand of 'ssue • Within a few months they also spawn and die. .
Load more

Recommended publications
  • Review of the Lampreys (Petromyzontidae) in Bosnia and Herzegovina: a Current Status and Geographic Distribution
    Review of the lampreys (Petromyzontidae) in Bosnia and Herzegovina: a current status and geographic distribution Authors: Tutman, Pero, Buj, Ivana, Ćaleta, Marko, Marčić, Zoran, Hamzić, Adem, et. al. Source: Folia Zoologica, 69(1) : 1-13 Published By: Institute of Vertebrate Biology, Czech Academy of Sciences URL: https://doi.org/10.25225/jvb.19046 BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Complete website, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/terms-of-use. Usage of BioOne Complete content is strictly limited to personal, educational, and non - commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. Downloaded From: https://bioone.org/journals/Journal-of-Vertebrate-Biology on 13 Feb 2020 Terms of Use: https://bioone.org/terms-of-use Journal of Open Acces Vertebrate Biology J. Vertebr. Biol. 2020, 69(1): 19046 DOI: 10.25225/jvb.19046 Review of the lampreys (Petromyzontidae) in Bosnia and Herzegovina:
    [Show full text]
  • Upper Basin Pallid Sturgeon Recovery Workgroup Annual Report
    UPPER BASIN PALLID STURGEON RECOVERY WORKGROUP 2004 ANNUAL REPORT Upper Basin Pallid Sturgeon Workgroup c/o Montana Fish, Wildlife and Parks 1420 East Sixth Helena MT 59620 August 2005 TABLE OF CONTENTS INTRODUCTION WORKGROUP MEETING NOTES 2004 Annual Meeting Notes – December 1-2, 2004 .............................................................5 March 9, 2005 Meeting Notes ...............................................................................................21 WORKGROUP LETTERS AND DOCUMENTS Intake BOR Letter..................................................................................................................29 Garrison Review Team Report Submission Letter to USFWS..............................................31 Review of pallid sturgeon culture at Garrison Dam NFH by the Upper Basin Pallid Sturgeon Review Team, March, 2005 ..............................................................36 RESEARCH AND MONITORING 2004 Pallid Sturgeon Recovery Efforts in the Upper Missouri River, Montana (RPMA #1), Bill Gardner, Montana Fish, Wildlife and Parks, Lewistown, MT...................49 Habitat Use, Diet, and Growth of Hatchery-reared Juvenile Pallid Sturgeon And Indigenous shovelnose sturgeon in the Missouri River avove Fort Peck Reservoir, Montana, Paul C. Gerrity, Christopher S. Guy, and William M. Gardner, Montana Cooperative Fishery Research Unit, Montana State University.............................65 Lower Missouri and Yellowstone Rivers Pallid Sturgeon Study, 2004 Report, Mtthew M. Klungle and Matthew W. Baxter, Montana
    [Show full text]
  • How to Use This Checklist
    How To Use This Checklist JAWLESS FISHES: SUPERCLASS AGNATHA Pikes: Family Esocidae LAMPREYS: CLASS CEPHALASPIDOMORPHI __ Grass Pickerel Esox americanus O Lampreys: Family Petromyzontidae __ Northern Pike Esox lucius O; Lake Erie and Hinckley Lake; The information presented in this checklist reflects our __ Silver Lamprey Ichthyomyzon unicuspis h current understanding of the status of fishes within Cleveland formerly common __ American brook Lamprey Lampetra appendix R; __ Muskellunge Esox masquinongy R; Lake Erie; Metroparks. You can add to our understanding by being a Chagrin River formerly common knowledgeable observer. Record your observations and __ *Sea Lamprey Petromyzon marinus O; Lake Erie; Minnows: Family Cyprinidae contact a naturalist if you find something that may be of formerly common; native to Atlantic Coast __ Golden Shiner Notemigonus crysoleucas C interest. JAWED FISHES: SUPERCLASS __ Redside Dace Clinostomus elongatus O GNATHOSTOMATA __ Southern Redbelly Dace Phoxinus erythrogaster R Species are listed taxonomically. Each species is listed with a BONY FISHES: CLASS OSTEICHTHYES __ Creek Chub Semotilus atromaculatus C common name, a scientific name and a note about its Sturgeons: Family Acipenseridae __ Hornyhead Chub Nocomis biguttatus h; formerly in occurrence within Cleveland Metroparks. Check off species __ Lake Sturgeon Acipenser fulvescens h; Lake Erie; Cuyahoga and Chagrin River drainages. that you identify in Cleveland Metroparks. Ohio endangered __ River Chub Nocomis micropogon C; Chagrin River; O Gars: Family
    [Show full text]
  • Strategic Approach to Problem Identification and Monitoring of Aquatic Invasive Species Within the Great Lakes Inventory and Monitoring Network Park Units
    U.S. Department of the Interior National Park Service Great Lakes Network Office Ashland, Wisconsin Strategic Approach to Problem Identification and Monitoring of Aquatic Invasive Species Within the Great Lakes Inventory and Monitoring Network Park Units Prepared by Henry Quinlan, Mark Dryer, Gary Czypinski, Jonathan Pyatskowit, and Jessica Krajniak, U.S. Fish and Wildlife Service, Ashland Fishery Resources Office Ashland, Wisconsin. Great Lakes Network Report GLKN/2007/08 September 2007 Errata Strategic Approach to Problem Identification and Monitoring of Aquatic Invasive Species Within the Great Lakes Inventory and Monitoring Network Park Units Henry Quinlan, Mark Dryer, Gary Czypinski, Jonathan Pyatskowit, and Jessica Krajniak U.S. Fish and Wildlife Service, Ashland Fishery Resources Office 2800 lakeshore Drive East Ashland, Wisconsin 54806 Great Lakes Network Report GLKN/2007/08 Erratum: Curly-leaf pondweed (Potamogeton crispus) was not known to be present in Voyageurs National Park as of the completion date of the report (September 2007). Appendix 5a, page 91: Replace the table for Curly Leaf Pondweed with the following: Curly Leaf Pondweed 1 2 3 4 5 T 6 7 APIS 3 1 8 8 7 27 N N GRPO 3 1 8 8 7 27 N N ISRO 3 1 8 8 7 27 N N PIRO 0 1 8 8 7 24 N N SLBE 0 10 8 8 7 33 N Y INDU 0 10 8 8 7 33 N N SACN 0 10 8 8 7 33 N Y MISS 0 10 8 8 7 33 N Y VOYA 7 10 8 8 7 40 N N Appendix 5b, page 95: Replace the table for Voyageurs National Park with the following: Voyageurs National Park Evaluation Questions Species 1 2 3 4 5 T 6 7 Rusty Crayfish 10 8 9 9 8 44 N Y Zebra Mussel 7 7 10 9 10 43 N N Quagga Mussel 6 7 9 8 10 40 N N Eurasian Water Milfoil 10 7 8 8 7 40 N N Curly Leaf Pondweed 7 10 8 8 7 40 N N Strategic Approach to Problem Identification and Monitoring of Aquatic Invasive Species Within the Great Lakes Inventory and Monitoring Network Park Units September 27, 2007 U.S.
    [Show full text]
  • Fish, Fish, and More Fish
    Vol. 7, No. 3 Kansas Wildlife & Parks Winter, 1997 Fish, Fish, and More Fish Inside... A Fish Is A Fish When? . 2 Did You Know . 3 It’s All In The Family . 4 Oh Give Me A Home Where The Fish Roam . 6 Aliens in Our Midsts... Non-Native Fish In Kansas . 8 AYear In The Life Of A Biologists . 9 Investigate A Fish . 10 Red Alert . 10 Reference Center Addedum . 11 Fishy Who’s Who . 13 The Wild Exchange . 14 Kansas Earth Day Events . 16 Words of W.I.L.D. 17 What’s Happening . 19 A Fish Is A Fish When? When asked to describe a fish, most of us . Most fish posses five types of fins would answer that fish live in water and used chiefly for stabilizing, steering, and take in oxygen through gills. Many kinds of braking. These are the dorsal fin on the animals that live in water are mistakenly centerline of the back, the tail fin, the anal called fish, from jellyfishes to starfishes. As fin on the underside opposite the dorsal fin, a rule, fish are rather easy to recognize a pair of pelvic fins on the belly, and a pair because they possess a combination of char- of pectoral fins behind the head. The pelvic acteristics not found in other animals. and pectoral fins can be compared to the Typically, fish are cold-blooded animals with arms and legs of mammal and their posi- backbones, gills, fins instead of legs, and tioning on the fish provides an important scales covering the body.
    [Show full text]
  • Fisheries Reproductive Biology Outline Defining Some Terms
    10/21/2011 Fisheries Reproductive Biology Presented by Nikolai Klibansky 0.8 0.4 0.0 Outline • I. Introduction • II. Diversity of Reproductive Biology in Fishes • III. Organizing Diversity: Breeding Systems • IV. Fisheries Reproductive Biology -Major ideas -The Nitty Gritty -Methodologies Defining some terms • fish reproductive biology – biology – physiology – ecology 1 10/21/2011 Defining some terms • Fish reproductive biology • Fisheries reproductive biology Fish RB: Diversity Pink anemonefish Port Jackson shark (Amphiprion perideraion ) (Heterodontus portusjacksoni ) California grunion, Anglerfish Leuresthes tenuis (Linophryne indica ) Fish RB: Taxonomy 2 10/21/2011 Fish RB: Taxonomy* Kingdom: Phylum: Subphylum: Superclass: Class: Animalia Chordata Vertebrata Agnatha Cephalaspidomorphi Myxini Pteraspidomorphi Osteichthyes Actinopterygii Sarcopterygii Chondrichthyes Amphibia Aves Mammalia *Branch length does NOT reflect genetic distance Reptilia Fish RB Diversity MAIN SOURCE: Helfman, G.S., Colette, B.B., and Facey, D.E. 1997. The Diversity of Fishes. Blackwell Science, Malden, MA. Superclass Agnatha • Class Cephalaspidomorphi (lampreys) – RB relatively well understood – Gonochoristic – Semelparous – Anadromous (migrate up to 1000km!) – Make nests – Spawn many small demersal eggs 3 10/21/2011 Superclass Agnatha • Class Myxini (hagfishes) – RB poorly understood – Apparently gonochoristic – External fertilization – Few, large, unique, demersal eggs – Eggs incubate for about 2 months Class Chondrichthyes • Subclass Elasmobranchii (sharks, skates, and rays) – RB fairly diverse within group – Typically late maturity (sharks, 6-18 years) – Gonochoristic – Sexual dimorphism • Males with claspers, females without • Dentition and skin thickness due to spawning behavior – Internal fertilization – Shark gestation period averages 9-12 mo. Class Chondrichthyes • Subclass Elasmobranchii (sharks, skates, and rays) – 40% of elasmobranchs, including all skates, are oviparous (egg laying). Eggs fairly large with hard outer case attach to substrate.
    [Show full text]
  • Life History Strategies of Fishes, However Most Have Focused on Growth, Mortality and Reproduction, and Rarely Included Trophic Ecology
    Christian-Albrecht Universität zu Kiel Leibniz Institut für Meereswissenschaften Habilitationsschrift Life-History Strategies of Recent Fishes: a Meta-Analysis vorgelegt von Dr. Rainer Froese Kiel, November 2005 1 Table of Content Abstract ...................................................................................................................................... 4 Introduction ................................................................................................................................ 6 Material and Methods............................................................................................................... 11 Results and Discussion............................................................................................................. 13 Key Components of Life-history Strategies......................................................................... 13 Phylogeny......................................................................................................................... 13 Size................................................................................................................................... 14 Trophic Level ................................................................................................................... 16 Productivity ...................................................................................................................... 17 Relationships between Size, Trophic Level and Productivity.............................................. 22 Available
    [Show full text]
  • Fiftee N Vertebrate Beginnings the Chordates
    Hickman−Roberts−Larson: 15. Vertebrate Beginnings: Text © The McGraw−Hill Animal Diversity, Third The Chordates Companies, 2002 Edition 15 chapter •••••• fifteen Vertebrate Beginnings The Chordates It’s a Long Way from Amphioxus Along the more southern coasts of North America, half buried in sand on the seafloor,lives a small fishlike translucent animal quietly filtering organic particles from seawater.Inconspicuous, of no commercial value and largely unknown, this creature is nonetheless one of the famous animals of classical zoology.It is amphioxus, an animal that wonderfully exhibits the four distinctive hallmarks of the phylum Chordata—(1) dorsal, tubular nerve cord overlying (2) a supportive notochord, (3) pharyngeal slits for filter feeding, and (4) a postanal tail for propulsion—all wrapped up in one creature with textbook simplicity. Amphioxus is an animal that might have been designed by a zoologist for the classroom. During the nineteenth century,with inter- est in vertebrate ancestry running high, amphioxus was considered by many to resemble closely the direct ancestor of the vertebrates. Its exalted position was later acknowledged by Philip Pope in a poem sung to the tune of “Tipperary.”It ends with the refrain: It’s a long way from amphioxus It’s a long way to us, It’s a long way from amphioxus To the meanest human cuss. Well,it’s good-bye to fins and gill slits And it’s welcome lungs and hair, It’s a long, long way from amphioxus But we all came from there. But amphioxus’place in the sun was not to endure.For one thing,amphioxus lacks one of the most important of vertebrate charac- teristics,a distinct head with special sense organs and the equipment for shifting to an active predatory mode of life.
    [Show full text]
  • Chapter 16 Study Guide
    CHAPTER 16 FISHES STUDY GUIDE 16.1 What Is a Fish? A. Approximately 28,000 living species—more than all other species of vertebrates combined B. Adaptations that have fitted them to almost every conceivable aquatic environment C. Overview 1. “Fish” has many usages extending beyond what are actually considered fish today (e.g., starfish, etc.). 2. A modern fish is an aquatic vertebrate with gills, limbs (if present) in the form of fins, and usually with a skin covered in scales of dermal origin. 3. Fishes do not form a monophyletic group. 4. The common ancestor of fishes is also an ancestor of land vertebrates; therefore in pure cladistics, this would make land vertebrates “fish”—a nontraditional and awkward usage. 5. They are adapted to live in a medium 800 times denser than air. 6. They can adjust to the salt and water balance of their environment. 7. Their gills are efficient at extracting oxygen from water that has 1/20 the oxygen of air. 8. A lateral line system detects water currents and vibrations, a sense of “distant touch.” 9. Evolution in an aquatic environment both shaped and constrained its evolution. 10. “Fish” refers to one or more individuals of one species; “fishes” refers to more than one species. 16.2 Ancestry and Relationships of Major Groups of Fishes A. History 1. Fishes descended from an unknown free-swimming protochordate ancestor. 2. Earliest fish-like vertebrates were a paraphyletic group of agnathan fishes (Figure 16.1). a. Agnathans include extinct ostracoderms and living hagfishes and lampreys. b. Ostracoderms gave rise to jawed gnathostomes.
    [Show full text]
  • Some Attempts at Phylogeny of Early Vertebrates George M
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by University of Northern Iowa Proceedings of the Iowa Academy of Science Volume 60 | Annual Issue Article 96 1953 Some Attempts at Phylogeny of Early Vertebrates George M. Robertson Grinnell College Copyright © Copyright 1953 by the Iowa Academy of Science, Inc. Follow this and additional works at: https://scholarworks.uni.edu/pias Recommended Citation Robertson, George M. (1953) "Some Attempts at Phylogeny of Early Vertebrates," Proceedings of the Iowa Academy of Science: Vol. 60: No. 1 , Article 96. Available at: https://scholarworks.uni.edu/pias/vol60/iss1/96 This Research is brought to you for free and open access by UNI ScholarWorks. It has been accepted for inclusion in Proceedings of the Iowa Academy of Science by an authorized editor of UNI ScholarWorks. For more information, please contact [email protected]. Robertson: Some Attempts at Phylogeny of Early Vertebrates Some Attempts at Phylogeny of Early Vertebrates By GEORGE M. ROBERTSON There is an often-quoted reply of a mountain-climber to the question of his motives in mountain climbing. "Why do I want to climb that mountain?· Because it is there." The same char­ acteristic of curiosity has driven men to investigate all sorts of things aside from mountains, and in many, perhaps most, cases we make the same reply if we are really honest. So in paleontology one generally starts with the small-boy motive and some fortunate souls continue with it. They are the rock­ hounds, the human "pack-rats", like the famous Lauder Dick, the Baker of Thurso.
    [Show full text]
  • Topic 16: Phylum Chordata
    BIOL 1030 – TOPIC 16 LECTURE NOTES Topic 16: Deuterostomes: Phylum Chordata (Ch. 34) I. Phylum Chordata (chordates) [clade] – general features A. key traits: deuterostomes with notochord, jointed appendages, and segmentation B. four key features present at some point in life cycle of all chordates: 1. dorsal, hollow nerve cord – becomes brain and/or spinal cord 2. notochord - flexible, fibrous rod along back (replaced by vertebrae in advanced vertebrates) 3. pharyngeal gill slits - openings in the throat region 4. postanal tail – most other animals with tails near the anus have anus at end of tail 5. these features may each be lost or altered in the adult 6. three subphyla: Cephalochordata, Urochordata, and Vertebrata II. Nonvertebrate chordates A. Subphylum Cephalochordata (clade) – lancelets 1. fishlike creatures that bury selves in mud and filter feed 2. all four key chordate feature present in adults 3. like vertebrates, muscles broken up into bands called myomeres (body segmentation) 4. essentially no brain in adults B. Subphylum Urochordata (clade) – sea squirts, tunicates 1. barrel-shaped, sessile, filter-feeders 2. many secrete and live in a tough cellulose sac (tunic) as adults 3. only have pharyngeal gill slits as adults, other chordate characters only present in tadpole-like larvae 4. incurrent and excurrent siphons 5. no brain in adults III. Subphylum Vertebrata (clade) A. more properly called Craniata (read on and see if you can figure out why) 1 of 10 BIOL 1030 – TOPIC 16 LECTURE NOTES B. characteristics 1. head with brain and skull 2. vertebral column – during development in most (all but Myxini), surrounding and ultimate replacement of notochord by bony or bone-like, hollow vertebrae; also, encase brain in protective box (skull or cranium) of bone or cartilage 3.
    [Show full text]
  • Vertebrate Natural History Lab Manual John W. Bickham Michael J. Smolen Christopher R. Harrison 1997 Revision Departme
    WFSC 302: Vertebrate Natural History Lab Manual John W. Bickham Michael J. Smolen Christopher R. Harrison 1997 Revision Department of Wildlife & Fisheries Sciences Texas A&M University Spring 2009 Revision by Toby Hibbitts Acknowedgements The authors would like to acknowledge all those students and teaching assistants who have contributed to the continuing evolution of this lab manual. We would also like to thank Eduardo G. Salcedo for his excellent drawings of the fish, herps and protochordates. 1 Kingdom Animalia Phylum Hemichordata Class Enteropneusta Acorn Worms Class Pterobranchia Phylum Chordata Subphylum Urochordata Class Ascidiacea Benthic Tunicates Class Larvacea Pelagic Tunicates Class Thaliacea Salps Subphylum Cephalochordata Amphioxus Order Myxiniformes Family Myxinidae Hagfish Subphylum Vertebrata Superclass Agnatha Class Cephalaspidomorphi Order Petromyzontiformes Family Petromyzontidae Lampreys Superclass Gnathostomata Class Chondrichthyes Subclass Holocephali Order Chimaeriformes Family Chimaeridae Ratfish Subclass Elasmobranchii Order Pristiformes Family Pristidae Sawfishes Order Carcharhiniformes Family Sphyrnidae Hammerheads Order Orectolobiformes Family Ginglymostomatidae Nurse Shark Order Torpediniformes Family Torpedinidae Electric Rays Order Myliobatiformes Family Dasyatidae Stingrays Order Rajiformes Family Rajidae Skates Class Osteichthyes Subclass Sarcopterygii Order Lepidosireniformes Family Lepidosirenidae African Lungfishes Subclass Actinopterygii Order Polypteriformes Family Polypteridae Bichirs Order Acipenseriformes
    [Show full text]