DOCSLIB.ORG

Database Stats

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Database Stats Database stats The following provides an overview of the content of the Living Planet Database (LPD) as of 5th June 2018. If you think you have or know of any data which could be added to the LPD, please get in touch with us at [email protected]. Number of populations and species Database growth over time Figure 1 Data accumulation since the online database was established. All previous data were transferred from the offline version of the database. Since the online database was established the time and date of entry are saved with the record, enabling us to track how many populations and species are being added over time. There are now 3,903 species from 19,278 populations in the database (Figure 1). The relatively steady increase over time has been punctuated by two steep increases in records which coincide with the completion of certain reports and projects. Number of species and populations by class Birds are the dominant class in the database, contributing the majority of species and almost half of populations (Figure 2). Fish1 form a similar portion of the species in the database. 1 Fish aren’t technically one class but a group comprising the following classes. Actinoptergyii, Cephalaspidomorphi, Myxini, Sarcopterygii, Elasmobranchii and Holocephali (with the latter two sometimes joined as Chondrichthyes). These different classes are combined for ease of interpretation. 1 b) a) Figure 2 Pie charts showing the number of a) species and b) populations in the Living Planet Database by class. Looking at the representation of classes in the LPI in more detail, Figure 3 shows how the number of species in the database compares to the total estimated number of species in the world. Birds once again have the highest representation of any class, followed by mammals, while reptiles have the lowest representation followed by amphibians and fish (Figure 3). Birds are the best-studied class so one reason for the high representation achieved is that there are many publications about different bird species. Figure 3 Graph showing the number of species in the Living Planet Database (solid bars) as a subset of the total number of species in the class based on figures from the relevant taxonomic authorities (hollow bars). 2 Number of species and populations by system Terrestrial species form the bulk of records in the LPI, though at the population level marine and terrestrial are more evenly matched (Figure 4). Considering that freshwater systems cover a substantially smaller portion of the world’s surface, it is not surprising that fewer species and populations from that system are contained in the LPI. Figure 4 Pie charts showing the distribution of a) species and b) populations in the Living Planet Database across the terrestrial, marine and freshwater system. Time-series length The majority of records cover 3-5 years of population data (Figure 5). There are over 3,000 records with the minimum amount of population data, 2 years. There is an unusual jump, in an otherwise decreasing trend in the number of populations with longer time series, with many records running from 1970 to 2011-2015.This is likely due to the large proportion of time-series stemming from long- term monitoring programmes such as the North American Breeding Bird Survey. Figure 5 Bar chart showing the distribution of populations according to their length. 3 Temporal distribution of data The number of populations and species which have a data point in a given year rises steadily from 1970, reaching a peak of >11,000 and > 2,600 – respectively - in the 1990s. After this point, numbers drop rapidly. As research on wildlife population change is still ongoing in more recent years, this reduction in the number of contributing populations and species is mainly due to a lag in the publication of collected data. In addition, data are published at such a rate so as to create a backlog of time-series to be entered into the database, and newer data sources are unlikely to be added unless they are in line with the current focus of data collection. Figure 6 The number of populations and species which have a data point in a given year. Data sources The majority of population records were sourced from peer-reviewed scientific journals (Figure 7). Secondary sources are those where an article or report uses population information from another typically referenced source. These are the second most common data source. Other sources include expert judgements, other unspecified sources and population records from an unknown source. 4 Figure 7 Pie chart showing the distribution of population sources in the database. Distribution There is an unequal spatial distribution of populations in the LPI, with more populations coming from Europe and North America than anywhere else for both terrestrial & freshwater, and marine systems (Figure 8). These two regions alone account for 10,909 populations – over half of all populations in the database. The figures also highlight the large gaps in distribution for both terrestrial and freshwater, and for marine populations. 5 a) b) Figure 8 Map of a) terrestrial & freshwater, and b) marine populations in the Living Planet Database. Only populations monitored in a specific location are plotted on the map. 6 Current data gaps The records which are currently contained in the LPD have been added opportunistically using published data, with data entry often following the focus of projects in progress. There is also a bias in available data from particular regions and species groups and from publications in the English language. If we compare the number of species currently represented in the LPD with the number of known vertebrate species globally, we can identify gaps in coverage. This provides an opportunity to target data entry towards these taxonomic and geographic gaps. Table 1 and 2 present the biggest data gaps in the LPD split into systems, classes and biogeographic realms. Overall, fish are the most underrepresented group in the database, followed by reptiles. If you think you have data which could be used to address these gaps, please get in touch with us at [email protected]. Table 1 The top 5 least well represented group/realm combinations in the Living Planet Database for terrestrial and freshwater systems. RANK REALM CLASS 1 Neotropical FW fish 2 Indo-Malaya FW fish 3 Neotropical Reptilia 4 Afrotropical FW fish 5 Afrotropical Reptilia Table 2 The top 4 least well represented group/realm combinations in the Living Planet Database for the marine system. RANK REALM CLASS 1 Tropical and Sub-tropical Indo-Pacific Fish 2 S.Temperate and Antarctic Fish 3 Atlantic Tropical and Sub-tropical Fish 4 Arctic Fish 7 .
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]
  • 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;
    [Show full text]