24-1 CHAPTERCHAPTER Chordates Chordates. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-2.

24-1 CHAPTERCHAPTER Chordates Chordates

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-3 Diversity Overview “Fish” has many usages extending beyond what are actually considered fishes today (e.g., starfish, etc.) “Fish” has many usages extending beyond what are actually considered fishes today (e.g., starfish, etc.) A modern fish A modern fish Aquatic vertebrate with gills, limbs (if present) in the form of fins, and usually with a skin covered in scales of dermal origin Aquatic vertebrate with gills, limbs (if present) in the form of fins, and usually with a skin covered in scales of dermal origin Fishes Fishes Do not form a monophyletic group Do not form a monophyletic group In an evolutionary sense, can be defined as all vertebrates that are not tetrapods In an evolutionary sense, can be defined as all vertebrates that are not tetrapods

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-4 Common ancestor of fishes is also an ancestor of land vertebrates Common ancestor of fishes is also an ancestor of land vertebrates Therefore in pure cladistics, would make land vertebrates “fish”- a nontraditional and awkward usage Therefore in pure cladistics, would make land vertebrates “fish”- a nontraditional and awkward usage Approximately 24,600 living species Approximately 24,600 living species Include more species than all other vertebrates combined Include more species than all other vertebrates combined Adapted to live in medium 800 times denser than air Adapted to live in medium 800 times denser than air Can adjust to the salt and water balance of their environment Can adjust to the salt and water balance of their environment Diversity

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-5 Gills are efficient at extracting oxygen from water that has 1/20 the oxygen of air Gills are efficient at extracting oxygen from water that has 1/20 the oxygen of air Lateral line system detects water currents and vibrations, a sense of “distant touch” Lateral line system detects water currents and vibrations, a sense of “distant touch” Evolution in an aquatic environment both shaped and constrained its evolution Evolution in an aquatic environment both shaped and constrained its evolution “Fish” refers to one or more individuals of one species “Fish” refers to one or more individuals of one species “Fishes” refers to more than one species “Fishes” refers to more than one species Diversity

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-7 Ancestry and Relationships of Major Groups of Fishes History Descended from an unknown free-swimming protochordate ancestor about 550 million years ago Descended from an unknown free-swimming protochordate ancestor about 550 million years ago Earliest fish-like vertebrates: Group of agnathan fishes Earliest fish-like vertebrates: Group of agnathan fishes Agnathans Agnathans Include extinct ostracoderms and living hagfishes and lampreys Include extinct ostracoderms and living hagfishes and lampreys Hagfishes lack vertebrae Hagfishes lack vertebrae Lampreys have rudimentary vertebrae Lampreys have rudimentary vertebrae

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-8 Included in subphylum Vertebrata because they have a cranium and other vertebrate homologies Included in subphylum Vertebrata because they have a cranium and other vertebrate homologies Unique enough to be assigned to separate classes Unique enough to be assigned to separate classes Remaining fish have paired appendages and join tetrapods as a monophyletic lineage of gnathostomes Remaining fish have paired appendages and join tetrapods as a monophyletic lineage of gnathostomes Gnathostomes Gnathostomes Appear in the Silurian fossil record with fully formed jaws Appear in the Silurian fossil record with fully formed jaws No intermediate forms between agnathans are known No intermediate forms between agnathans are known The Devonian is called the Age of Fishes The Devonian is called the Age of Fishes Ancestry and Relationships of Major Groups of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-9 One group, the placoderms, became extinct in the Carboniferous and left no direct descendants One group, the placoderms, became extinct in the Carboniferous and left no direct descendants Cartilaginous Fishes Cartilaginous Fishes Lost heavy dermal armor and adopted skeleton of cartilage Lost heavy dermal armor and adopted skeleton of cartilage Flourished during the Devonian and Carboniferous Flourished during the Devonian and Carboniferous Almost became extinct at end of the Paleozoic Almost became extinct at end of the Paleozoic Increased in numbers in the early Mesozoic, diversifying to form a modern shark assemblage Increased in numbers in the early Mesozoic, diversifying to form a modern shark assemblage Ancestry and Relationships of Major Groups of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-10 Acanthodians Acanthodians Well represented in the Devonian Well represented in the Devonian Became extinct by the lower Permian Became extinct by the lower Permian Resemble bony fish but have heavy spines on all fins except the caudal fin Resemble bony fish but have heavy spines on all fins except the caudal fin Probably the sister group of bony fishes Probably the sister group of bony fishes Ancestry and Relationships of Major Groups of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-12 Bony Fishes Bony Fishes Dominant fishes today Dominant fishes today Two distinct lineages Two distinct lineages Ray-finned fishes Ray-finned fishes Lobe-finned fishes Lobe-finned fishes Ray-finned fishes radiated to form modern bony fishes Ray-finned fishes radiated to form modern bony fishes Lobe-finned fishes are a relict group with few species today Lobe-finned fishes are a relict group with few species today Include the sister group of the tetrapods Include the sister group of the tetrapods Ancestry and Relationships of Major Groups of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-13 Living Jawless Fishes Overview Living jawless fishes include hagfishes and lampreys Living jawless fishes include hagfishes and lampreys About 43 species of hagfishes are known and about 41 species of lamprey are described About 43 species of hagfishes are known and about 41 species of lamprey are described Members of both groups lack jaws, internal ossification, scales, or paired fins Members of both groups lack jaws, internal ossification, scales, or paired fins Both groups share porelike gill openings and an eel-like body Both groups share porelike gill openings and an eel-like body Recent molecular analysis shows lampreys and hagfishes forming a monophyletic unit Recent molecular analysis shows lampreys and hagfishes forming a monophyletic unit Many zoologists do not support this grouping thus we take the view that hagfishes form the sister group of a clade that includes lampreys and gnathostomes Many zoologists do not support this grouping thus we take the view that hagfishes form the sister group of a clade that includes lampreys and gnathostomes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-16 Class Myxini: Hagfishes Entirely marine Entirely marine Scavengers and predators of annelids, molluscs, dead or dying fishes, etc. Scavengers and predators of annelids, molluscs, dead or dying fishes, etc. Enters dead or dying animal through orifice or by digging inside using keratinized plates on tongue Enters dead or dying animal through orifice or by digging inside using keratinized plates on tongue Nearly blind Nearly blind Locate food by an acute sense of smell and touch Locate food by an acute sense of smell and touch To provide leverage To provide leverage Ties knot in tail and passes it forward to press against prey Ties knot in tail and passes it forward to press against prey Special glands along body secrete fluid that becomes slimy in contact with seawater Special glands along body secrete fluid that becomes slimy in contact with seawater Living Jawless Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-17 Body fluids are in osmotic equilibrium with seawater Body fluids are in osmotic equilibrium with seawater Circulatory system includes three accessory hearts in addition to a heart behind gills Circulatory system includes three accessory hearts in addition to a heart behind gills Reproduction of Hagfishes Reproduction of Hagfishes Copenhagen Academy of Science offered a prize over a century ago for information on hagfish breeding habits………it remains unclaimed Copenhagen Academy of Science offered a prize over a century ago for information on hagfish breeding habits………it remains unclaimed In some species, females outnumber males by 100 to 1 In some species, females outnumber males by 100 to 1 Females produce small numbers of large, yolky eggs 2-7 centimeters in diameter Females produce small numbers of large, yolky eggs 2-7 centimeters in diameter Living Jawless Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-18 Class Petromyzontida: Lampreys Diversity Diversity All lampreys in Northern Hemisphere belong to the family Petromyzontidae All lampreys in Northern Hemisphere belong to the family Petromyzontidae Marine lamprey Petromyzon marinus Marine lamprey Petromyzon marinus Occurs on both Atlantic coastlines Occurs on both Atlantic coastlines Grows to a length of one meter Grows to a length of one meter 20 species of lampreys in North America 20 species of lampreys in North America Half belong to nonparasitic brook-dwelling species Half belong to nonparasitic brook-dwelling species Living Jawless Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-20 Reproduction and Development Reproduction and Development Ascend freshwater streams to breed Ascend freshwater streams to breed Marine forms are anadromous Marine forms are anadromous Leave the sea as adults to spawn upstream Leave the sea as adults to spawn upstream In North America In North America All spawn in winter or spring All spawn in winter or spring Males build nest by lifting stones with oral discs and using body vibrations Males build nest by lifting stones with oral discs and using body vibrations Female anchors to a rock and male attaches to her head Female anchors to a rock and male attaches to her head As eggs are shed into nest, the male fertilizes them As eggs are shed into nest, the male fertilizes them Adults die soon thereafter Adults die soon thereafter Living Jawless Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-21 Eggs hatch in two weeks into ammoceotes larvae Eggs hatch in two weeks into ammoceotes larvae Lives first on yolk supply and drifts downstream to burrow into sandy areas Lives first on yolk supply and drifts downstream to burrow into sandy areas Suspension-feeder until it metamorphoses into an adult Suspension-feeder until it metamorphoses into an adult Change to an adult involves eruption of eyes, keratinized teeth replacing the hood, enlargement of fins, maturation of gonads and modification of gill openings Change to an adult involves eruption of eyes, keratinized teeth replacing the hood, enlargement of fins, maturation of gonads and modification of gill openings Living Jawless Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-22 Parasitic Lampreys Parasitic Lampreys Marine, parasitic lampreys migrate to the sea Marine, parasitic lampreys migrate to the sea Other species remain in freshwater Other species remain in freshwater Attach to a fish by a sucker-like mouth Attach to a fish by a sucker-like mouth Sharp teeth rasp through flesh as they suck fluids Sharp teeth rasp through flesh as they suck fluids Inject anticoagulant into a wound Inject anticoagulant into a wound When engorged, lamprey drops off but wound may be fatal to fish When engorged, lamprey drops off but wound may be fatal to fish Parasitic freshwater adults live 1–2 years before spawning and dying Parasitic freshwater adults live 1–2 years before spawning and dying Anadromous forms live 2–3 years Anadromous forms live 2–3 years Nonparasitic lampreys do not feed Nonparasitic lampreys do not feed Digestive tract degenerates as an adult Digestive tract degenerates as an adult They spawn and die They spawn and die Living Jawless Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-24 Sea Lamprey Invasion of the Great Lakes Region Sea Lamprey Invasion of the Great Lakes Region No lampreys were in the U. S. Great Lakes west of Niagara Falls until the Welland Ship Canal was deepened between 1913 and 1918 No lampreys were in the U. S. Great Lakes west of Niagara Falls until the Welland Ship Canal was deepened between 1913 and 1918 Sea lampreys moved first through Lake Erie to Lakes Huron, Michigan, and Superior Sea lampreys moved first through Lake Erie to Lakes Huron, Michigan, and Superior Lampreys preferred lake trout Lampreys preferred lake trout Destroyed this commercial species along with overfishing Destroyed this commercial species along with overfishing Living Jawless Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-25 Then rainbow trout, whitefish, lake herring, chubs, and other species were destroyed Then rainbow trout, whitefish, lake herring, chubs, and other species were destroyed Lamprey populations declined both from depletion of food and control measures Lamprey populations declined both from depletion of food and control measures Chemical larvicides in spawning streams Chemical larvicides in spawning streams Release of sterile males Release of sterile males Living Jawless Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-26 Class Chondrichthyes: Cartilaginous Fishes Overview About 970 living species About 970 living species Smaller and more ancient group Smaller and more ancient group Well-developed sense organs, powerful jaws, and predaceous habits helped them survive Well-developed sense organs, powerful jaws, and predaceous habits helped them survive True bone is completely absent throughout the class True bone is completely absent throughout the class Phosphatized mineral tissues retained in teeth, scales, and spines Phosphatized mineral tissues retained in teeth, scales, and spines Nearly all are marine Nearly all are marine Only 28 species live primarily in freshwater Only 28 species live primarily in freshwater After whales, sharks are the largest living vertebrates, reaching 12 meters in length After whales, sharks are the largest living vertebrates, reaching 12 meters in length

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-27 Subclass Elasmobranchii: Sharks, Skates and Rays 13 living orders of elasmobranchs with about 937 total species described 13 living orders of elasmobranchs with about 937 total species described Order Carcharhiniformes Order Carcharhiniformes Contains the coastal tiger and bull sharks and the hammerhead Contains the coastal tiger and bull sharks and the hammerhead Order Lamniformes Order Lamniformes Contains large, pelagic sharks such as the white and mako shark Contains large, pelagic sharks such as the white and mako shark Class Chondrichthyes: Cartilaginous Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-29 Order Squaliformes Order Squaliformes Contains dogfish sharks Contains dogfish sharks Order Rajiformes Order Rajiformes Contain skates Contain skates Order Myliobatiformes Order Myliobatiformes Contains several groups of rays (stingrays, manta rays, etc.) Contains several groups of rays (stingrays, manta rays, etc.) Class Chondrichthyes: Cartilaginous Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-30 Form and Function Form and Function Sharks are among the most gracefully streamlined of fishes Sharks are among the most gracefully streamlined of fishes Body is fusiform Body is fusiform Thrust and lift provided by an asymmetrical heterocercal tail Thrust and lift provided by an asymmetrical heterocercal tail Vertebral column turns upward and extends into dorsal lobe of caudal fin Vertebral column turns upward and extends into dorsal lobe of caudal fin Fins include Fins include Paired pectoral and pelvic fins Paired pectoral and pelvic fins One or two median dorsal fins One or two median dorsal fins One median caudal fin One median caudal fin Sometimes a median anal fin Sometimes a median anal fin Class Chondrichthyes: Cartilaginous Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-32 In males, the medial part of the pelvic fin is modified to form a clasper used in copulation In males, the medial part of the pelvic fin is modified to form a clasper used in copulation Paired nostrils are anterior to mouth Paired nostrils are anterior to mouth Lateral eyes are lidless Lateral eyes are lidless Behind each eye is a spiracle Behind each eye is a spiracle Remnant of the first gill slit Remnant of the first gill slit Tough, leathery skin with placoid scales Tough, leathery skin with placoid scales Reduce water turbulence Reduce water turbulence Detect prey at a distance by large olfactory organs sensitive to one part per 10 billion Detect prey at a distance by large olfactory organs sensitive to one part per 10 billion Class Chondrichthyes: Cartilaginous Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-34 Nostrils to each side of the hammerhead shark may improve stereo-olfaction Nostrils to each side of the hammerhead shark may improve stereo-olfaction Prey may also be located from long distances sensing low frequency vibrations in the lateral line Prey may also be located from long distances sensing low frequency vibrations in the lateral line Consists of neuromasts in interconnected tubes and pores on side of body Consists of neuromasts in interconnected tubes and pores on side of body At close range, switch to vision At close range, switch to vision Most have excellent vision even in dimly lit water Most have excellent vision even in dimly lit water Up close, sharks are guided by bioelectric fields that surround all animals Up close, sharks are guided by bioelectric fields that surround all animals Class Chondrichthyes: Cartilaginous Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-36 Electroreceptors, the ampullae of Lorenzini, are located on the shark’s head Electroreceptors, the ampullae of Lorenzini, are located on the shark’s head Upper and lower jaws equipped with sharp, triangular teeth that are constantly replaced Upper and lower jaws equipped with sharp, triangular teeth that are constantly replaced Mouth opens into large pharynx, containing openings to gill slits and spiracles Mouth opens into large pharynx, containing openings to gill slits and spiracles Short esophagus runs to stomach Short esophagus runs to stomach Liver and pancreas open into short, straight intestine Liver and pancreas open into short, straight intestine Spiral valve in intestine slows passage of food and increases absorptive area Spiral valve in intestine slows passage of food and increases absorptive area Class Chondrichthyes: Cartilaginous Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-38 Rectal gland secretes NaCl and assists the opisthonephric kidney Rectal gland secretes NaCl and assists the opisthonephric kidney Heart chambers provide standard circulatory flow through gills and body Heart chambers provide standard circulatory flow through gills and body Elasmobranchs retain nitrogenous compounds in the blood Elasmobranchs retain nitrogenous compounds in the blood Raises blood solute concentrations and eliminates the osmotic inequality between blood and seawater Raises blood solute concentrations and eliminates the osmotic inequality between blood and seawater Class Chondrichthyes: Cartilaginous Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-39 Reproduction and Development Reproduction and Development Fertilization is internal Fertilization is internal Maternal support of embryo is variable Maternal support of embryo is variable Includes oviparous, ovoviviparous, and viviparous species Includes oviparous, ovoviviparous, and viviparous species “Mermaid’s purse” “Mermaid’s purse” Horny capsule encasing eggs laid by some oviparous species Horny capsule encasing eggs laid by some oviparous species Class Chondrichthyes: Cartilaginous Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-40 Form and Function of Rays Form and Function of Rays More than half of elasmobranchs are rays More than half of elasmobranchs are rays Most specialized for benthic life Most specialized for benthic life Dorsoventrally flattened body and enlarged pectoral fins used to propel themselves Dorsoventrally flattened body and enlarged pectoral fins used to propel themselves Respiratory water enters through large spiracles on top of the head Respiratory water enters through large spiracles on top of the head Teeth adapted for crushing prey Teeth adapted for crushing prey Molluscs, crustaceans, and sometimes small fish Molluscs, crustaceans, and sometimes small fish Stingrays Stingrays Have whiplike tail with spines and venom glands Have whiplike tail with spines and venom glands Electric rays Electric rays Have large electric organs on each side of head Have large electric organs on each side of head Class Chondrichthyes: Cartilaginous Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-43 Subclass Holocephali: Chimeras Small subclass Small subclass Remnants of a line that diverged from the earliest shark lineage Remnants of a line that diverged from the earliest shark lineage 33 extant species 33 extant species Fossil chimaeras Fossil chimaeras First appeared in the Carboniferous, reached a zenith in the Cretaceous and early Tertiary, and then declined First appeared in the Carboniferous, reached a zenith in the Cretaceous and early Tertiary, and then declined Mouth lacks teeth Mouth lacks teeth Equipped with large flat plates for crushing food Equipped with large flat plates for crushing food Upper jaw fused to the cranium Upper jaw fused to the cranium Feed on seaweed, molluscs, echinoderms, crustaceans, and fish Feed on seaweed, molluscs, echinoderms, crustaceans, and fish Class Chondrichthyes: Cartilaginous Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-45 Osteichthyes: Bony Fishes Origin, Evolution and Diversity In early to middle Silurian, a lineage of fishes with bony endoskeletons gave rise to a clade that contains 96% of living fishes and all living tetrapods In early to middle Silurian, a lineage of fishes with bony endoskeletons gave rise to a clade that contains 96% of living fishes and all living tetrapods 3 features unite bony fishes and tetrapod descendants 3 features unite bony fishes and tetrapod descendants Endochondral bone replaces cartilage during development Endochondral bone replaces cartilage during development Lung or swim bladder is present Lung or swim bladder is present Evolved as an extension of gut Evolved as an extension of gut Have several cranial and dental characters unique to clade Have several cranial and dental characters unique to clade

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-47 Osteichthyes: Bony Fishes Do not define a natural group and is a term of convenience rather than a valid taxon Do not define a natural group and is a term of convenience rather than a valid taxon Bony operculum and branchiostegal rays associate them with acanthodians Bony operculum and branchiostegal rays associate them with acanthodians By the middle Devonian, bony fishes developed into 2 major lineages By the middle Devonian, bony fishes developed into 2 major lineages Ray-finned fishes, class Actinopterygii, radiated to form modern bony fishes Ray-finned fishes, class Actinopterygii, radiated to form modern bony fishes Lobe-finned fishes, class Sarcopterygii, include lungfishes and the coelacanth Lobe-finned fishes, class Sarcopterygii, include lungfishes and the coelacanth Operculum increased respiratory efficiency Operculum increased respiratory efficiency Helped draw water across gills Helped draw water across gills

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-48 Osteichthyes: Bony Fishes Gas-filled structure off the esophagus Gas-filled structure off the esophagus Helped in buoyancy and also in hypoxic waters Helped in buoyancy and also in hypoxic waters In fishes that use these pouches for respiration In fishes that use these pouches for respiration Pouches are called lungs Pouches are called lungs In fishes that use these pouches for buoyancy In fishes that use these pouches for buoyancy Pouches are called swim bladders Pouches are called swim bladders Specialization of jaw musculature improved feeding Specialization of jaw musculature improved feeding

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-49 Class Actinopterygii: Ray-finned Fishes Diversity Over 27,000 species of ray-finned fishes Over 27,000 species of ray-finned fishes Palaeoniscids Palaeoniscids Earliest forms Earliest forms Small, had large eyes, a heterocercal caudal tail, and interlocking scales with an outer layer of ganoin Small, had large eyes, a heterocercal caudal tail, and interlocking scales with an outer layer of ganoin Single dorsal fin and numerous bony rays derived from scales stacked end to end Single dorsal fin and numerous bony rays derived from scales stacked end to end Fossils have been found as early as the late Silurian Fossils have been found as early as the late Silurian Flourished throughout the late Paleozoic Flourished throughout the late Paleozoic Distinct from lobe-finned fishes and saw the ostracoderms, etc. decline Distinct from lobe-finned fishes and saw the ostracoderms, etc. decline

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-53 Bichirs Bichirs In the clade Cladista In the clade Cladista Have lungs, heavy ganoid scales, and other characteristics similar to the palaeoniscids Have lungs, heavy ganoid scales, and other characteristics similar to the palaeoniscids 16 species of which all live in the freshwaters of Africa 16 species of which all live in the freshwaters of Africa Chondrosteons Chondrosteons 27 species of freshwater and anadromous sturgeons and paddlefishes 27 species of freshwater and anadromous sturgeons and paddlefishes Dam construction, overfishing, and pollution have led to their decline Dam construction, overfishing, and pollution have led to their decline Class Actinopterygii: Ray-finned Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-55 Neopterygians Neopterygians Appeared in late Permian and radiated extensively during the Mesozoic Appeared in late Permian and radiated extensively during the Mesozoic During the Mesozoic, one lineage gave rise to the modern bony fishes: Teleost During the Mesozoic, one lineage gave rise to the modern bony fishes: Teleost 2 surviving early neopterygians are the bowfin and gars 2 surviving early neopterygians are the bowfin and gars Gars and bowfin gulp air and use the vascularized swim bladder to supplement gills Gars and bowfin gulp air and use the vascularized swim bladder to supplement gills Class Actinopterygii: Ray-finned Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-57 Teleosts Teleosts Constitute 96% of all living fishes and half of all vertebrates Constitute 96% of all living fishes and half of all vertebrates Range from 10 millimeters to 17 meters long, and up to 900 kilograms in weight Range from 10 millimeters to 17 meters long, and up to 900 kilograms in weight Survive from 5,200 meters altitude in Tibet to 8,000 meters below the ocean surface Survive from 5,200 meters altitude in Tibet to 8,000 meters below the ocean surface Some can live in hot springs at 44 o C while others survive under Antarctic ice at - 2 o C Some can live in hot springs at 44 o C while others survive under Antarctic ice at - 2 o C Some live in salt concentrations three times seawater Some live in salt concentrations three times seawater Others found swamps devoid of oxygen Others found swamps devoid of oxygen Class Actinopterygii: Ray-finned Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-59 Morphological Trends Heavy dermal armor replaced by light, thin, flexible cycloid and ctenoid scales Heavy dermal armor replaced by light, thin, flexible cycloid and ctenoid scales Some eels, catfishes, and others lost scales Some eels, catfishes, and others lost scales Increased mobility from shedding armor helps fish avoid predators and improved feeding efficiency Increased mobility from shedding armor helps fish avoid predators and improved feeding efficiency Fins changed to provide greater mobility and serve a variety of functions Fins changed to provide greater mobility and serve a variety of functions Braking, streamlining, and social communication Braking, streamlining, and social communication Homocercal tail allowed greater speed and buoyancy Homocercal tail allowed greater speed and buoyancy Jaw changed to increase suctioning and protrusion to secure food Jaw changed to increase suctioning and protrusion to secure food Class Actinopterygii: Ray-finned Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-60 Class Sarcopterygii: Lobe-finned Fishes Diversity Ancestor of tetrapods Ancestor of tetrapods Group of extinct sarcopterygian fishes called rhipdistians Group of extinct sarcopterygian fishes called rhipdistians Early sarcopterygians Early sarcopterygians Had lungs, gills, and a heterocercal-type tail Had lungs, gills, and a heterocercal-type tail During the Paleozoic, tail became a symmetrical diphycercal tail During the Paleozoic, tail became a symmetrical diphycercal tail Had powerful jaws, heavy, enameled scales with a dentine-like material called cosmine, and strong, fleshy, paired lobed fins Had powerful jaws, heavy, enameled scales with a dentine-like material called cosmine, and strong, fleshy, paired lobed fins Today, clade is represented by 8 fish species Today, clade is represented by 8 fish species 6 species of lungfishes and 2 species of coelacanths 6 species of lungfishes and 2 species of coelacanths

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-63 Lungfish Lungfish Australia lungfishes, unlike close relatives, rely on gill respiration and cannot survive long out of water Australia lungfishes, unlike close relatives, rely on gill respiration and cannot survive long out of water South American and African lungfish can live out of water for long periods of time South American and African lungfish can live out of water for long periods of time Rhipidistians and the coelacanth were termed crossopterygian: polyphyletic group no longer used Rhipidistians and the coelacanth were termed crossopterygian: polyphyletic group no longer used Rhipidistians flourished in late Paleozoic and then became extinct Rhipidistians flourished in late Paleozoic and then became extinct Include ancestors of tetrapods Include ancestors of tetrapods Class Sarcopterygii: Lobe-finned Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-64 The Coelacanth The Coelacanth Arose in the Devonian, radiated, reached a peak in the Mesozoic, and dramatically declined Arose in the Devonian, radiated, reached a peak in the Mesozoic, and dramatically declined Thought to be extinct 70 million years, a specimen was dredged up in 1938 Thought to be extinct 70 million years, a specimen was dredged up in 1938 More were caught off coast of the Comoro Islands and in Indonesia More were caught off coast of the Comoro Islands and in Indonesia Living coelacanth is a descendant of Devonian freshwater stock Living coelacanth is a descendant of Devonian freshwater stock Tail is diphycercal with a small lobe between the upper and lower caudal lobes Tail is diphycercal with a small lobe between the upper and lower caudal lobes Young coelacanths born fully formed after hatching from eggs up to 9 cm in diameter Young coelacanths born fully formed after hatching from eggs up to 9 cm in diameter Class Sarcopterygii: Lobe-finned Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-65 Structural and Functional Adaptations of Fishes Locomotion in Water Speed Speed Most fishes swim maximally at ten body lengths per second Most fishes swim maximally at ten body lengths per second Larger fish therefore swims faster Larger fish therefore swims faster Short bursts of speed are possible for a few seconds Short bursts of speed are possible for a few seconds Mechanism Mechanism Trunk and tail musculature propels a fish Trunk and tail musculature propels a fish Muscles are arranged in zigzag bands called myomeres Muscles are arranged in zigzag bands called myomeres Have the shape of a W on the side of fish Have the shape of a W on the side of fish Internally the bands are folded and nested Internally the bands are folded and nested Each myomere pulls on several vertebrae Each myomere pulls on several vertebrae

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-68 Fish undulations move backward against the water Fish undulations move backward against the water Produces a reactive force with two parts Produces a reactive force with two parts Thrust pushes fish forward and overcomes drag Thrust pushes fish forward and overcomes drag Lateral force makes the fish’s head “yaw” Lateral force makes the fish’s head “yaw” Large and rigid head minimizes yaw Large and rigid head minimizes yaw Swaying body generates too much drag for fast speed Swaying body generates too much drag for fast speed Fast fish are less flexible and generate all thrust with caudal fins Fast fish are less flexible and generate all thrust with caudal fins Fast oceanic fish have swept-back, sickle-like tail fins, similar to high-aspect ratio wings of birds Fast oceanic fish have swept-back, sickle-like tail fins, similar to high-aspect ratio wings of birds Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-70 Economy Economy Swimming is the most economical form of motion because water buoys the animal Swimming is the most economical form of motion because water buoys the animal Energy cost per kilogram of body weight for traveling one kilometer is 0.39 Kcal for swimming, 1.45 Kcal for flying, and 5.43 for walking Energy cost per kilogram of body weight for traveling one kilometer is 0.39 Kcal for swimming, 1.45 Kcal for flying, and 5.43 for walking Yet to be determined how aquatic animals can move through water with little turbulence Yet to be determined how aquatic animals can move through water with little turbulence Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-71 Neutral Buoyancy and the Swim Bladder Fish are slightly heavier than water Fish are slightly heavier than water To keep from sinking, a shark must continually move forward To keep from sinking, a shark must continually move forward Fins keep it “angled up” Fins keep it “angled up” Shark liver has a special fatty hydrocarbon, or squaline, that acts to keep the shark a little buoyant Shark liver has a special fatty hydrocarbon, or squaline, that acts to keep the shark a little buoyant Swim bladder, as a gas-filled space, is the most efficient flotation device Swim bladder, as a gas-filled space, is the most efficient flotation device Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-72 Swim bladder arose from paired lungs of primitive Devonian bony fishes Swim bladder arose from paired lungs of primitive Devonian bony fishes Absent in tunas, some abyssal fishes, and most bottom dwellers Absent in tunas, some abyssal fishes, and most bottom dwellers Fish controls depth by adjusting volume of gas in swim bladder Fish controls depth by adjusting volume of gas in swim bladder Due to pressure, as a fish descends, the bladder is compressed making the total density of the fish greater Due to pressure, as a fish descends, the bladder is compressed making the total density of the fish greater As a fish ascends, the bladder expands making the fish lighter and it will rise ever faster As a fish ascends, the bladder expands making the fish lighter and it will rise ever faster Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-74 Gas is removed in 2 ways Gas is removed in 2 ways Primitive physostomous fishes Primitive physostomous fishes Pneumatic duct connecting swim bladder and esophagus Pneumatic duct connecting swim bladder and esophagus Advanced teleosts are physoclistous Advanced teleosts are physoclistous Pneumatic duct is lost and gas must be secreted into the blood from a vascularized area Pneumatic duct is lost and gas must be secreted into the blood from a vascularized area Both types require gas to be secreted into the bladder from the blood via the gas gland Both types require gas to be secreted into the bladder from the blood via the gas gland A network of capillaries, rete mirabile, is a countercurrent exchange system used to trap gases A network of capillaries, rete mirabile, is a countercurrent exchange system used to trap gases Gas gland secretes lactic acid that forces hemoglobin to release its load of oxygen Gas gland secretes lactic acid that forces hemoglobin to release its load of oxygen Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-75 Rete capillaries are short in surface-dwelling fish and very long in deep-sea fishes Rete capillaries are short in surface-dwelling fish and very long in deep-sea fishes A few shallow-water-inhabiting physostomes gulp air to fill the swim bladder A few shallow-water-inhabiting physostomes gulp air to fill the swim bladder Even at 2400 meters, the bladder is inflated, mostly with oxygen, but also with variable amounts of nitrogen, carbon dioxide, argon, and even some carbon monoxide, and the pressure within the air bladder must exceed 240 atmospheres Even at 2400 meters, the bladder is inflated, mostly with oxygen, but also with variable amounts of nitrogen, carbon dioxide, argon, and even some carbon monoxide, and the pressure within the air bladder must exceed 240 atmospheres Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-76 Hearing and Weberian Ossicles Fish, like other vertebrates, detect sounds as vibrations in the inner ear. Fish, like other vertebrates, detect sounds as vibrations in the inner ear. A teleost group, ostariophysans A teleost group, ostariophysans Possess Weberian ossicles Possess Weberian ossicles Allow them to hear faint sounds over a much broader range than other teleosts Allow them to hear faint sounds over a much broader range than other teleosts Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-78 Respiration Fish gills are filaments with thin epidermal membranes folded into plate-like lamellae Fish gills are filaments with thin epidermal membranes folded into plate-like lamellae Gills are inside the pharyngeal cavity and covered with a movable flap, the operculum Gills are inside the pharyngeal cavity and covered with a movable flap, the operculum Operculum protects delicate gill filaments and streamlines body Operculum protects delicate gill filaments and streamlines body Pumping action by operculum helps move water through gills Pumping action by operculum helps move water through gills Although it appears pulsatile, water flow over gills is continuous Although it appears pulsatile, water flow over gills is continuous Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-80 Water flow is opposite to the blood flow Water flow is opposite to the blood flow Countercurrent exchange maximizes exchange of gases Countercurrent exchange maximizes exchange of gases Some bony fishes remove 85% of the oxygen from water passing over gills Some bony fishes remove 85% of the oxygen from water passing over gills Some active fishes use ram ventilation Some active fishes use ram ventilation Forward movement is sufficient to force water across gills Forward movement is sufficient to force water across gills Such fishes are asphyxiated in a restrictive aquarium even if the water is saturated with oxygen Such fishes are asphyxiated in a restrictive aquarium even if the water is saturated with oxygen Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-81 Fishes Out of Water Fishes Out of Water Lungs of lungfishes allow them to respire in air Lungs of lungfishes allow them to respire in air Eels can wriggle over land during rainy weather Eels can wriggle over land during rainy weather Use skin as major respiratory surface Use skin as major respiratory surface A bowfin uses gills at cooler temperatures and lung-like swim bladder at higher temperatures A bowfin uses gills at cooler temperatures and lung-like swim bladder at higher temperatures Electric eel has degenerate gills and gulps air through vascular mouth cavity Electric eel has degenerate gills and gulps air through vascular mouth cavity Indian climbing perch spends most of its time on land, breathing air in special chambers Indian climbing perch spends most of its time on land, breathing air in special chambers Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-82 Osmotic Regulation Freshwater is hypotonic to fish blood Freshwater is hypotonic to fish blood Water enters body and salt is lost by diffusion Water enters body and salt is lost by diffusion Scaled and mucous-covered body is mostly impermeable, but gills allow water and salt fluxes Scaled and mucous-covered body is mostly impermeable, but gills allow water and salt fluxes Freshwater fishes are hyperosmotic regulators Freshwater fishes are hyperosmotic regulators Opisthonephric kidney pumps excess water out Opisthonephric kidney pumps excess water out Special salt-absorbing cells located in epithelium actively move salt ions from water into fishes’ blood Special salt-absorbing cells located in epithelium actively move salt ions from water into fishes’ blood Systems are efficient Systems are efficient Freshwater fish devote little energy to maintaining osmotic balance Freshwater fish devote little energy to maintaining osmotic balance Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-84 About 90% of bony fishes are restricted to either freshwater or seawater habitats About 90% of bony fishes are restricted to either freshwater or seawater habitats Euryhaline fishes live in estuaries where salinity fluctuates throughout day Euryhaline fishes live in estuaries where salinity fluctuates throughout day Marine bony fishes are hypoosmotic regulators Marine bony fishes are hypoosmotic regulators Blood is hypotonic to seawater Blood is hypotonic to seawater Tend to lose water and gain salt Tend to lose water and gain salt Risks “drying out” Risks “drying out” Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-85 To compensate for water loss, a marine teleost drinks seawater To compensate for water loss, a marine teleost drinks seawater Brings in more unneeded salt Brings in more unneeded salt Carried by blood to gills and secreted by special salt-secretory cells Carried by blood to gills and secreted by special salt-secretory cells Divalent ions of magnesium, sulfate and calcium are left in intestine and leave body with the feces Divalent ions of magnesium, sulfate and calcium are left in intestine and leave body with the feces Some divalent ions enter bloodstream and are excreted by kidney by tubular secretion Some divalent ions enter bloodstream and are excreted by kidney by tubular secretion Glomeruli are small or missing Glomeruli are small or missing Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-86 Feeding Behavior Fish devote most of their time searching for food to eat and eating Fish devote most of their time searching for food to eat and eating With the evolution of jaws With the evolution of jaws Fish left a passive filter-feeding life and entered a predator-prey battle Fish left a passive filter-feeding life and entered a predator-prey battle Most fish are carnivores Most fish are carnivores Feed on zooplankton, insect larvae, and other aquatic animals Feed on zooplankton, insect larvae, and other aquatic animals Most fish do not chew food Most fish do not chew food Would block water flow across the gills Would block water flow across the gills Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-89 A few can briefly crack prey items with teeth, or have molar-like teeth in throat A few can briefly crack prey items with teeth, or have molar-like teeth in throat Most swallow food whole Most swallow food whole Easy with water pressure that sweeps food in when the mouth opens Easy with water pressure that sweeps food in when the mouth opens Some are herbivores Some are herbivores Eat plants and algae Eat plants and algae Crucial intermediates in food chain Crucial intermediates in food chain Suspension feeders Suspension feeders Crop abundant microorganisms of the sea Crop abundant microorganisms of the sea Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-90 Many plankton feeders swim in large schools and using gill rakers to strain food Many plankton feeders swim in large schools and using gill rakers to strain food Omnivores feed on both plants and animals Omnivores feed on both plants and animals Scavengers feed on organic debris Scavengers feed on organic debris Detritovores consume fine particulate organic matter Detritovores consume fine particulate organic matter Parasitic fishes suck body fluids of other fishes Parasitic fishes suck body fluids of other fishes Digestion follows the vertebrate plan Digestion follows the vertebrate plan A few lack stomachs A few lack stomachs Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-91 Intestine tends to be shorter in carnivores and long and coiled in herbivores Intestine tends to be shorter in carnivores and long and coiled in herbivores Stomach primarily stores food Stomach primarily stores food Intestine digests and absorbs nutrients Intestine digests and absorbs nutrients Teleost fishes have pyloric ceca Teleost fishes have pyloric ceca Apparently for fat absorption Apparently for fat absorption Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-92 MigrationEels Have presented a life history puzzle for centuries Have presented a life history puzzle for centuries Catadromous, developing to maturity in freshwater but migrating to sea to spawn Catadromous, developing to maturity in freshwater but migrating to sea to spawn In fall, adults swim downriver to the sea to spawn, but none return In fall, adults swim downriver to the sea to spawn, but none return In spring, many young eels or “elvers” appear in coastal waters and swim upstream In spring, many young eels or “elvers” appear in coastal waters and swim upstream Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-94 Grassi and Calandruccio (1896) reported that elvers were advanced juveniles Grassi and Calandruccio (1896) reported that elvers were advanced juveniles True larval eels were tiny leaf-shaped, and transparent True larval eels were tiny leaf-shaped, and transparent Johann Schmidt traced eel migrations by examining plankton nets from commercial fishermen Johann Schmidt traced eel migrations by examining plankton nets from commercial fishermen Adult eels were tracked to the Sargasso Sea southeast of Bermuda Adult eels were tracked to the Sargasso Sea southeast of Bermuda At depths of 300 meters or more, eels spawn and die At depths of 300 meters or more, eels spawn and die Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-95 Minute larvae journey back to the streams of Europe and North America Minute larvae journey back to the streams of Europe and North America American eel larvae make trip back in 8 months since the Sargasso Sea is much closer to American coastline, whereas the European eel larvae take three years American eel larvae make trip back in 8 months since the Sargasso Sea is much closer to American coastline, whereas the European eel larvae take three years Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-96 Homing Salmon Salmon are anadromous Salmon are anadromous Grow up in sea but return to freshwater to spawn Grow up in sea but return to freshwater to spawn 6 species of Pacific salmon and 1 Atlantic salmon migrates 6 species of Pacific salmon and 1 Atlantic salmon migrates Atlantic salmon makes repeated spawning runs Atlantic salmon makes repeated spawning runs Pacific species spawn once and die Pacific species spawn once and die Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-98 Pacific species of sockeye salmon Pacific species of sockeye salmon Migrates downstream Migrates downstream Roams the Pacific for 4 years Roams the Pacific for 4 years Returns to spawn in headwaters of parents’ stream Returns to spawn in headwaters of parents’ stream Young fish are imprinted on odor of their stream Young fish are imprinted on odor of their stream May navigate to stream mouth by sensing magnetic field of the earth or angle of the sun, and then smelling their way home May navigate to stream mouth by sensing magnetic field of the earth or angle of the sun, and then smelling their way home Salmon are endangered by stream degradation from logging, pollution and hydroelectric dams Salmon are endangered by stream degradation from logging, pollution and hydroelectric dams Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-99 Reproduction and Growth Most fishes are dioecious with external fertilization and external development Most fishes are dioecious with external fertilization and external development Guppies and mollies represent ovoviviparous fish that develop in ovarian cavity Guppies and mollies represent ovoviviparous fish that develop in ovarian cavity Some sharks are viviparous with some kind of placental attachment to nourish young Some sharks are viviparous with some kind of placental attachment to nourish young Most oviparous pelagic fish lay huge numbers of eggs Most oviparous pelagic fish lay huge numbers of eggs Female cod may release 4–6 million eggs Female cod may release 4–6 million eggs Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-101 Near-shore and bottom-dwelling species lay larger, typically yolky, nonbuoyant and adhesive eggs Near-shore and bottom-dwelling species lay larger, typically yolky, nonbuoyant and adhesive eggs Some bury eggs Some bury eggs Many attach eggs to vegetation Many attach eggs to vegetation Some incubate eggs in their mouth Some incubate eggs in their mouth Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-103 Many benthic spawners guard eggs Many benthic spawners guard eggs Male is usually the guard Male is usually the guard Freshwater fishes produce nonbuoyant eggs Freshwater fishes produce nonbuoyant eggs The more care provided, the fewer the eggs produced The more care provided, the fewer the eggs produced Freshwater fishes may have elaborate mating dances before spawning Freshwater fishes may have elaborate mating dances before spawning Egg soon takes up water, the outer layer hardens and cleavage occurs Egg soon takes up water, the outer layer hardens and cleavage occurs Structural and Functional Adaptations of Fishes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-105 Blastoderm develops and yolk is consumed Blastoderm develops and yolk is consumed Fish hatches carrying a semitransparent yolk sac to supply food until it can forage Fish hatches carrying a semitransparent yolk sac to supply food until it can forage Change from larva to adult may be dramatic in body shape, fins, color patterns, etc. Change from larva to adult may be dramatic in body shape, fins, color patterns, etc. Growth is temperature dependent Growth is temperature dependent Warmer fish grow more rapidly Warmer fish grow more rapidly Annual rings on scales, otoliths, etc. reflect seasonal growth cycles Annual rings on scales, otoliths, etc. reflect seasonal growth cycles Most fish continue to grow throughout life Most fish continue to grow throughout life Structural and Functional Adaptations of Fishes

24-1 CHAPTERCHAPTER Chordates Chordates. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-2.

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24-1 CHAPTERCHAPTER Chordates Chordates. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-2.

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Presentation on theme: "24-1 CHAPTERCHAPTER Chordates Chordates. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24-2."— Presentation transcript:

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