Essential Fish Biology: Diversity, Structure, and Function

424 Pages·2017·63.848 MB·English

by  Derek Burton, Margaret Burton

Essential Fish Biology

Essential Fish Biology
Diversity, Structure and Function
Derek Burton
Professor Emeritus, Department of Biology,
Memorial University of Newfoundland, Canada
Margaret Burton
Professor Emeritus, Department of Biology,
Memorial University of Newfoundland, Canada
1
3
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The front cover image shows a mormyrid, capable of electrolocation, and the back cover image
shows beach spawning capelin
First Edition published in 2018
Impression: 1
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ISBN 978–0–19–878555–2 (hbk.)
ISBN 978–0–19–878556–9 (pbk.)
DOI 10.1093/oso/9780198785552.001.0001
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Preface
St. John’s, with its historical associations in the New- We have limited this book to a single volume ap-
foundland fishery, has been a stimulating location in propriate to an introduction to the subject. We have
which to develop an overview of fish biology. Since also avoided a partitioning of chapters between a
the arrival of Europeans in Newfoundland in the large number of specialist authors which has been a
fifteenth century, fishing has been a major economic trend in the case of fish physiology texts. Although
activity in the province. More recently St. John’s has such ‘sectionalized’ books can be advantageous
become an important centre in the Northern Hemi- to advanced readers, students new to the subject
sphere for the study of fish biology and fisheries sci- can benefit from a more concise and consistent ap-
ence. These studies involve a number of university proach, written by fewer authors. Our objective is
departments and institutions as well as Newfound- to provide a comprehensive introduction to each
land and Canadian government research units. This topic, together with detailed references leading to
has produced a diversity of teaching and research the roots of current knowledge. To provide useful
programmes in fish biology, fisheries and aquacul- background some topics are prefaced by a brief ac-
ture, attracting undergraduate and graduate stu- count of basic aspects of relevant more general cel-
dents from within the province and internationally. lular, anatomical or physiological biology. The book
The aim of this book is to provide an introductory will be suitable for undergraduate and graduate
overview of the functional biology of fish and how students in fish biology, fisheries and aquaculture,
it may be influenced by the contrasting habitat con- as well as for more general readers interested in fish.
ditions within the aquatic environment. The book In a world in which security of food supplies will
includes advances in comparative animal physiol- become an increasingly important issue, a sound
ogy made since the mid-twentieth century, which development of aquaculture and sustainability of
have greatly influenced our understanding of fish fisheries will be integral to planning. This implies
function or have generated questions on this sub- a comprehensive understanding of factors influenc-
ject, still to be resolved. Fish taxa represent the larg- ing fish survival, including their basic physiology
est number of vertebrates, with over 30,000 extant in their natural habitats and in captivity.
species. Much of our knowledge, apart from tax- We wish to thank the many participants in in-
onomy and habitat descriptions, has been based on formal discussions and more formal seminars in
relatively few of these species, usually those which St. John’s and at conferences elsewhere, often em-
live in fresh water and/or are of commercial inter- phasizing how much remains to be researched in
est. Unfortunately there has also been a tendency this subject as well as what has been accomplished.
to base interpretation of fish physiology on that Members of the Biology Department of Memorial
of mammalian systems, as well as to rely on a few University have given courteous assistance and
type species of fish. We have attempted to redress advice. We particularly thank Dr Paul Marino,
the balance by using examples of fish from a wide Shena Quinton, Roy Ficken, Peter Earle and Kerri
range of species and habitats, emphasizing diver- Green, as well as Mike Hatcher, Richard Hu, Julia
sity as well as recognizing shared attributes with Trahey and Graham Hillier at the Ocean Sciences
other vertebrates. Centr e. We have benefited from the specific help
v
vi Preface
and cooperation of Dr G. Allen, Dr A. Bal, Dr Vern Nancy Simmons for information on copyright. We
Barbe r, Dr Eastman, Dr Fryer, the family of Dr are grateful to Ian Sherman, Lucy Nash and Beth-
Greenwood, Dr R. Khan, Prof Dr Schmitt and Dr any Kershaw of Oxford University Press for their
Stevens. Many institutions have helped and coop- help, guidance and patience. We are also grateful to
erated with information retrieval, and we thank Narmatha Vaithiyanathan for organizing the final
Joe Tomelleri for the ‘slender chub’ photograph, assembly of the material. Finally, we acknowledge
Dr Craig Purchase for the capelin photograph and the many students whose curiosity and interesting
Catherine Burton for the ‘garden eels’. We appre- questions over the years prompted us to develop
ciated Rudie Kuiter’s advice and patience in ac- this book which we hope will be helpful to many
cessing photographs of coral-reef fish. We thank people. We welcome comments and corrections.
Chapter 1
Fish diversity
Classification and variety
1.1 Summary
Fish have a long evolutionary history and have successfully colonized a large range of habitats including deep oceans and
shallow ponds.
Formal classifications of the very numerous fish species are subject to adjustment as new information accrues. The major
divergences separate the extant jawless fish from the jawed fish, and ‘cartilaginous’ fish from those with bony skeletons. A few
extant bony fish species are regarded as ‘relict’ (or primitive), remnants of ancient lineages.
Fish diversity parallels the numerous habitat niches they occupy, with size attained from minute to enormous, shapes from
spherical to flat to elongated, and other attributes, both morphological and functional, enable ‘lifestyles’ mainly aquatic but,
for a few, even terrestrial.
1.2 Introduction dichotomy of structure is recognized by the num-
ber of embryonic cell layers, most having three, be-
Fish are aquatic vertebrates with gills and fins ing therefore triploblasts (Appendix 1.1). In many
rather than lungs and legs, although some fish lack animals including the vertebrates the middle em-
paired fins and others have lungs. In geologic time bryonic cell layer develops a cavity (the coelom,
they preceded the other vertebrate groups which Appendix 1.1) which allows gut movement. The
are derived from them. formal classification of animals assigns each spe-
Although a few fish spend quite a lot of time on cies to a series of groups or taxa, the largest or most
land, almost all fish species are still recognizably char- inclusive being a Phylum. Each Phylum is usually
acterized by their need to be in water, with very spe- divided into Classes, and each Class into Orders.
cial adaptations to that particular environment with Orders are subdivided into Families, each of which
its density, low oxygen and high thermal capacity re- contains Genera. Any individual genus contains
ducing rapid temperature changes. Many fish species one or more species. Within this basic system may
are also high on the trophic level, being predaceous be many subunits; for example, there can be Sub-
even as juveniles, and for many active carnivores this classes, Infraclasses and so on to fit the complicated
means rapid movement and a fairly complex sensory relationships within the groups. Where there are
system. Fish represent huge diversity in shape, size, large numbers of similar species the term ‘species
colour and habit. The distribution of particular genera flock’ has been utilized; the definition of a species
may be widespread, either naturally (deep-sea grena- usually depends on morphological differences, and
diers) or by introduction (trout, carp) or severely lim- taxonomists set up a ‘type’ specimen for reference.
ited (desert pupfish, cave-fish), and the numbers of Structurally fish share with other vertebrates a
individuals in different species may also be extremely basic body plan of bilateral symmetry, with a dor-
numerous (some marine species) or very few for spe- sal supporting structure the notochord (hence Phy-
cies in specialized habitats such as caves. lum Chordata) as a precursor to the series of harder
Among the huge array of multicellular ani- vertebrae. All vertebrates are metamerically seg-
mals classified as such in the Animal Kingdom a mented, which means the serial repetition of body
Essential Fish Biology: Diversity, Structure and Function. Derek Burton & Margaret Burton.
© Derek Burton & Margaret Burton 2018. Published 2018 by Oxford University Press.
DOI 10.1093/oso/9780198785552.001.0001
2 EssEnTiAl Fish Biology
parts, a system which facilitates locomotion in the widely used classifications from the 1970s (‘old’)
many animals which have this organization. The and the more recent (‘new’, Nelson 2006). The most
segmentation is not as obvious as in, for example, recent radical revision (Nelson et al. 2016) is dealt
earthworms or millipedes, but its existence can be with in the text.
seen in the vertebrae, the 10, perhaps +1 (11.8), pairs As with other organisms, the species to which
of cranial nerves, the gills and gill supports (gill an individual is assigned is best characterized and
arches), the spinal nerves and many of the blood named by a Latin-based binomial to avoid muddle
vessels supplying the body wall. (Appendix 1.3). Each species belongs to a genus (al-
Physiologically fish share with other vertebrates a ways capitalized) such as ‘Gadus’ for cod-like fish.
high degree of activity except under extreme condi- The individual species also has a ‘specific’ name
tions and a capacity to regulate the composition of which, with the generic name, provides the ‘bino-
body fluids, though temperature regulation is lim- mial’. Thus Atlantic cod is ‘Gadus morhua’. The nam-
ited for most fish to seeking optimum conditions. ing convention is to italicize the constituents of a
Currently fish are by far the most numerous binomial, and if the genus is used repeatedly then it
vertebrates, both as individuals and species, rep- can be reduced to a capital, such as G. morhua. The
resenting roughly 50 per cent of all vertebrate spe- strict naming convention, generally at first use in
cies now alive (extant). It is generally agreed that a publication, and notably in the title, is to include
there are in excess of 20,000 extant fish species; the name of the first person (Linnaeus and post-Lin-
Nelson (1994) recognized about 25,000 species, naean) describing the species, immediately after the
and this number is augmented as new species are Latin binomial (Appendix 1.4).
described, differentiated and/or discovered, for For identification purposes, particularly for live
example from the deeper oceans or from big river fish, superficial characteristics may be very useful.
systems such as the Amazon/Rio Negro complex. Hence the presence of a small, but readily recog-
Thus Nelson (2006) reports nearly 28,000 species, nized, adipose fin between the dorsal fin and the
Berra (2007) more than 29,000 and Nelson et al. tail may indicate a fish of the ‘salmon–trout’ group-
(2016) state 32,000. ing in comparison to perch in the same habitat al-
Fish are the oldest group of vertebrates, with an though adipose fins are also found on some catfish
enormous diversity of first, jawless, and subse- and characins, as well as in five other orders (Reim-
quently, jawed species showing adaptive radiation in chen and Temple 2004). Similarly, fish shape can be
aquatic habitats and prolific speciation as far back as indicative; whereas the skewed eyes and flat shape
the Ordovician Era for jawless fish (480–390 million of ‘flatfish’ together place these fish, the slim shape
years ago, mya). The Devonan Era (350–300 mya) of eels and barracuda are only helpful. Similarly al-
indeed has been termed the ‘Age of Fishes’ with nu- though several gill slits on each side, or ventrally,
merous species particularly associated with freshwa- place fish in the ‘shark–dogfish–ray’ category, the
ter during that time period (Romer 1955). The jawless presence of male claspers shared by this group and
fish are now reduced to two relict groups (hagfish the chimaeras (rabbit/ratfish) has obvious limita-
and lampreys), with a tendency towards a parasitic tions if a female is caught. Fortunately, however,
habit. Recently the hagfish have been detached from the general appearance of both groups is so differ-
the vertebrate classification altogether (Nelson et al. ent from other living fish that confusion is actually
2016), and are regarded as a sister group. most unlikely.
Because there are now so many different kinds
1.3 Classification of fish in addition to the very large number of
extinct forms, formal classification of fish (by
The large number of fish species presents a chal- taxonomists) has presented a formidable task as
lenge in identification and classification; the follow- new information becomes available. Revisions are
ing provides a brief overview. To aid orientation, ongoing at various levels; some species have un-
all species referred to are subsequently listed sep- dergone renaming or reclassification fairly often.
arately in the Index. Appendix 1.2 summarizes Rainbow trout which is apparently more a salmon
Fish divErsiTy 3
than a trout has shifted from Salmo irideus to Salmo
Phylum Chordata All animals with a notochord at
gairdneri to Oncorhynchus mykiss, placing it with some stage in their life cycle
the Pacific salmon such as chum and sockeye.
subphylum vertebrata (Craniata) All animals with a vertebral
At another taxonomic level some of the ‘primi- column
tive’ fish like gar, the bowfin, the lungfish and
superclass Agnatha Jawless fish
the coelacanth may have been shifted from one
superclass gnathostomata Jawed vertebrates
major grouping to another, with the lungfish and
grade Pisces Jawed fish
coelacanth now placed closer to the terrestrial ver-
tebrates than to most other fish. With this degree Class Chondrichthyes Cartilaginous fish, but not
sturgeons
of change in groupings, any classification scheme
Class osteichthyes Bony fish
may be regarded as temporary.
Some older nomenclatures have been incorpo-
rated in newer schemes but others have been lost, Figure 1.1 Fish classification based on nelson (1976).
albeit sometimes temporarily. Thus ‘Chondrostei’
1.3.1 Jawless fish
is retained for sturgeon-like fish as a Subclass but
Holostei is no longer always applied as a formal Most considerations of fish diversity divide fish into
taxon for Amia the bowfin (Nelson 2006), although those with jaws and those without, the latter being
still used and recognized informally and reinstated ‘Agnatha’ (Figure 1.1), many of which are now extinct,
as a Subclass by Nelson et al. (2016). The taxon with two living groups the hagfish and lampreys. In
‘Isospondyli’ (meaning similar vertebrae), used in 2016 Nelson and colleagues separated the hagfish
the nineteenth century for soft-finned teleosts (such from the lampreys and all other extant fish (Figure
as herring, trout) which also shared some basic 1.2) on the basis of lack of any vertebral elements (ar-
features like undifferentiated anterior vertebrae, cualia, 3.5.2) in hagfish. However as hagfish are noted
air bladders (if present) linked to the gut (phys- for the modification of various structures, including
ostomatous), posteriorly placed pelvic fins, was eyes, the lack of vertebrae may be secondary.
superseded early in the twentieth century (Bou- Jawless fish, such as osteostracomorphs with
lenger 1904), although still used by Gregory (1933, bony head shields (Figure 1.3), have been found in
reprinted 1959). deposits dating back to the Ordovician Era, with
During the latter half of the twentieth century, jawed fish gradually more prevalent into the De-
fish were classified as in Figure 1.1 and some of vonian. The term ‘ostracoderms’ was at one time
this nomenclature still stands, or is otherwise rec- a collective term used for early agnatha (Nelson
ognized as useful, but some recent changes to fish
classification have been profound (Nelson 2006;
Phylum Chordata
Nelson et al. 2016; Figure 1.2).
subphylum Craniata
The status of hagfish (1.3.1, Figure 1.2) is under
infraphylum Myxinomorpha hagfish
consideration; Nelson et al. (2016) removed them
infraphylum vertebrata vertebrates
from the vertebrates, a major adjustment. Hagfish
ancestors are only represented so far by a single superclass Petromyzontomorphi lampreys
possible fossil hagfish (Bardack 1998), with a further *superclass Pteraspidomorphi
type described more recently (Janvier and Sansom *superclass Anaspidomorphi
2015). Even more difficult to assess is the situation
*superclass Thelodontomorphi
with the conodonts and their possible relationship
*superclass osteostracomorphi
within the chordates (Aldridge and Donoghue 1998;
superclass gnathostomata Jawed
Nelson et al. 2016). Only very recently have entire
vertebrates
fossils of conodonts been available; previously these
animals were known only from their teeth, which Figure 1.2 A new classification for hagfish and lampreys after
were however abundant and perhaps reminiscent of nelson et al. (2016).
hagfish (Aldridge and Donoghue 1998). *Extinct.