Form and Function: Fish begin

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Form and Function Fish (begin)

• Marine Vertebrates Lecture 1

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Challenges of the marine environment

• Density
• Pressure
• Temperature

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Temperature stratification
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Challenges of the marine environment

• Density
• Pressure
• Temperature
• Light

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Light attenuation with depth
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Challenges of the marine environment

• Density
• Pressure
• Temperature
• Light
• Salinity
• Oxygen

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Oxygen vs. depth
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Challenges of the marine environment

• Density
• Pressure
• Temperature
• Light
• Salinity
• Oxygen
• Seasonality
• Substrate

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Vertebrate phylogeny

• Vertebrates are thought to be monophyletic,
  descended from a cephalochordate (or
  urochordate?) ancestor
• So ultimately, all marine vertebrates are related
• However, the marine vertebrates themselves are
  polyphyletic, with various groups arising from
  fresh water or land-based ancestors at different
  times.

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Fish phylogeny
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Likely common ancestor to vertebrates Phylum
ChordataSubphylum Cephalochordata

• Invertebrate chordate lancelet
• Larvae and adults have all chordate features
  (four shown plus endostyle thyroid precursor)
• Muscles develop from somites blocks of mesoderm
  (segmented)

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Subphylum Cephalochordata lancelets
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Fish phylogeny Craniata

• Derived character neural crest cells/cranium

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Neural crest (Craniata)
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Phylum Chordata, Subphylum Myxini Hagfish
Campbell, Fig. 34.9
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Fish phylogeny Phylum Chordata, Subphylum
Vertebrata

• Derived character vertebral column

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Subphylum VertebrataClass Cephalaspidomorphi
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Fish phylogeny Phylum Chordata, Subphylum
Vertebrata, Gnathostomes

• Derived characters jaws, bone, paired fins

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Gnathostomes

• Jaw development
• From which structures?
• Development of bone
• Which structures were first mineralized?
• Development of paired fins
• Hypothesis for origins?

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Class Chondrichthyes Subclass Elasmobranchii
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Elasmobranchii Features

• Skeleton
• Vertebral column
• Cranium
• Teeth
• Upper jaw
• Ceratotrichia
• Nostrils

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Elasmobranchii Features
Spiral valve within intestine Function?
Pelvic fins with claspers. Function?
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Elasmobranchii Features

• Gills
• Scales placoid
• Buoyancy

Australian Museum of Natural History
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Circulation
Campbell, Biology
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Respiration countercurrent exchange
Campbell, Biology
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Additional features

• Osmoregulation
• Reproduction
• Oviparity
• Ovoviviparity
• Viviparity

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Feeding
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Shark Orders
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Order Lamniformes mackerel sharks Overview
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Focus Family Lamnidae

• Adaptations for effective swimming
• Body shape (note snout!)
• Fins
• Ram ventilation
• Cruising speeds 3 km/h (great white)
• Speed bursts Up to 35 km/h (mako)
• Elevate body temperature
• Countercurrent heat exchange

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Countercurrent heat exchange Great white shark
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The Behavior of White Sharks and their Pinniped
Prey during predatory attacks

• Summary of research by Klimley, Pyle and
  Anderson, 1996 (for next Monday!)

Deskpicture.com
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Order LamniformesFocus basking sharks
Photos D. Burton
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Order Charcharhiniformes Groundsharks Overview
Photo Paul Humann
Photo Guillaume Chanfreau
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Order CharcharhiniformesFocus Hammerheads
Photo Guillaume Chanfreau
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Order CharcharhiniformesFocus reef sharks
(requim)
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Order Orectolobiformes Carpetsharks Overview
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Order OrectolobiformesFocus Wobbegongs
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Order OrectolobiformesFocus Nurse sharks
Photos Paul Humann
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Order OrectolobiformesFocus Whale sharks
Photo Werner Mischler
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Order HeterodontiformesBullhead sharks
Horn shark Photo Tom Campbell, Innerspace
VIsions
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Order Hexanchiformes
Photos Michigan Science Art
Bluntnose sevengill shark
Frill shark
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Order SqualiformesDogfish sharks
Spiny dogfish Photo J. Stafford-Deitsch
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Order SqualiformesCookie-cutter shark
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Order Pristiophoriformessawsharks
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Order SquatiniformesAngel sharks
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Skates and raysOverview
Photos Paul Humann
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Order Rajiformes skates
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Order Torpediniformeselectric rays
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Order Myliobatiformesbat rays, stingrays, manta
rays
Photo Paul Humann
Photo Andy Murch
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Class ChondricthyesSubclass Holocephali