Fish Chapter 18

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Fish Chapter 18
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Fig 18.3
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Fig 24-2
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Groupings

• SP Hyperotreti jawless fish
• C Myxini hagfish
• SP Vertebrata
• C Cephalaspidomorphi lampreys
• C Ostacoderm taxa
• Gnathostomata jawed
• C Chondrichthyes
• sc Elasmobranchii sharks and rays
• sc Holocephali chimaeras
• C Osteichthyes bony fish
• sc Actinopterygii ray-finned fishes
• sc Sarcopterygii fleshy-finned fishes

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Basics

• Fish not monopyletic
• 26,000 living species
• Live in variety of environments
• Salinity
• Pressure
• Gills and lateral line important evolutionary
  innovations

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AgnathaJawless fish

• Lack
• Jaws
• Internal ossification
• Scales
• Paired fins
• Pore-like gill openings
• Eel-like body

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C MyxiniHagfish

• Marine scavengers
• Literally digs into dead or dying fish
• Uses plates on tongue to dig
• Knots up body for leverage

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C Cephalaspidomorphi Lampreys

• Marine parasitic
• Attach with sucker-like mouth
• Anticoagulant
• Wound usually fatal to fish
• Freshwater usually non-parasitic
• Non-parasitic forms do not feed as adults
• Spawn and die

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Sucker-Like Mouth of a Lamprey
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Great Lakes

• Appeared in Lake Ontario in the 1830s through
  ship canals
• Spread to all of the Great Lakes
• Caused the collapse of lake trout, white fish and
  chub populations (1940-1950)

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Lamprey on Lake Trout
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Lamprey Life Cycle
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Adult Free Living Lamprey
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GnathostomaJawed fish

• Advanced sense organs
• Jaw
• Cartilaginous or bone
• Mainly predators

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C Chondrichthyes

• 850 living species
• Smaller and more ancient group
• True bone is completely absent
• Marine
• Subclasses
• Elasmobranchii sharks, skates and rays
• Holocephali chimeras

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SC ElasmobranchiiSharks, skates and rays

• Nine orders
• Half are rays, half are sharks
• Lets use sharks as our model organism
• Tough skin covered in placoid scales
• Well developed sensory system
• Lateral line
• Ampullae of lorenzini

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Placoid Scales
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Sensory systemFunctions in detecting and location

• Lateral line (neuromasts)
• Canal system running length of body, laterally
• Detect vibrations
• Ampullae of Lorenzini
• Receptors on head of sharks
• Able to sense bioelectric fields

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SC HolocephaliChimeras

• Remnants of line that diverged from the earliest
  shark lineage
• No teeth, but has large plates for crushing prey

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C OsteichthyesBony fish

• 96 of todays fish
• Bony operculum
• Specialization of jaw musculature

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Features uniting bony fish

• Bone is present
• Replaces cartilage developmentally
• Lungs or swim bladder
• Unique cranial/dental characters

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SC SarcopterygiiLobe-finned fishes

• 7 species alive today
• Lungs, gills, diphycercal tail
• Skin covered with layers of scales and enamel
• Sister group to tetrapods

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Types of caudal fins
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Lungfishes the Lobed-Finned Fish
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The Coelacanth

• Thought to be extinct for 70 million years
• Then they were dredged up and found for sale at
  markets (1938)

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SC ActinopterygiiRay-finned fishes

• Heavy dermal armor was replaced with flexible
  scales or missing altogether
• Increase mobility
• Swim bladder now for buoyancy only
• Most Homocercal tail greater mobility some
  heterocercal tail.

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Types of caudal fins
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Primitive Ray-Finned Fish Ganoid Scales
Heterocercal Tail
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Primitive Ray-Finned Fish have Ganoid Scales
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Advanced Ray-Finned Fish have Cycloid, Ctenoid,
or No Scales Homocercal Tail
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Killifish
The Plains Killifish Fundulus zebrinus
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Minnows
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Minnows
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Live Bearbearers Mosquito fish
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Darters and Perch
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Sculpins
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Sunfish
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Melissa being a true trooper and removing catfish
from gillnets from lake Ogallala, note the
T-shirt.
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Catfish
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Suckers
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Suckers
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Trout and Salmon
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Really Strange Fish
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The Big Picture

• Fish are not monophyletic
• Although variable, several features bind this
  group loosely together
• Humans have had an impact in making certain fish
  pests
• Fleshy-finned fish are the closest relatives to
  the tetrapods