Marine Vertebrates: Lecture 1
Form and Function: Fish
(begin)
Challenges of the marine
environment
• Density
• Pressure
• Temperature
Temperature stratification
Challenges of the marine
environment
• Density
• Pressure
• Temperature
• Light
Light attenuation with depth
Challenges of the marine
environment
• Density
• Pressure
• Temperature
• Light
• Salinity
• Oxygen
Oxygen vs. depth
Challenges of the marine
environment
•
•
•
•
•
•
•
•
Density
Pressure
Temperature
Light
Salinity
Oxygen
Seasonality
Substrate
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.
Fish phylogeny
Likely common ancestor to
vertebrates: Phylum Chordata
Subphylum 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)
Subphylum Cephalochordata: lancelets
Fish phylogeny: “Craniata”
• Derived character: neural crest
cells/cranium
Neural crest/
cranium
Neural crest (Craniata)
Phylum Chordata,
Subphylum Myxini: Hagfish
Campbell, Fig. 34.9
Fish phylogeny: Phylum Chordata,
Subphylum Vertebrata
• Derived character: vertebral column
Vertebral column
Subphylum Vertebrata;
Class Cephalaspidomorphi
Fish phylogeny: Phylum Chordata,
Subphylum Vertebrata, “Gnathostomes”
• Derived characters: jaws, bone, paired
fins
Jaws;
Bone;
Paired fins
Gnathostomes
• Jaw development
 From which structures?
• Development of bone
 Which structures were first mineralized?
• Development of paired fins
 Hypothesis for origins?
Class Chondrichthyes:
Subclass Elasmobranchii
Elasmobranchii: Features
• Skeleton
 Vertebral
column
 Cranium
 Teeth
 Upper jaw
 Ceratotrichia
• Nostrils
Elasmobranchii: Features
Spiral valve
within intestine:
Pelvic fins with
claspers.
Function?
Function?
Elasmobranchii: Features
• Gills
• Scales:
placoid
• Buoyancy
Australian
Museum of Natural
History
Circulation
Campbell, Biology
Respiration:
countercurrent exchange
Campbell, Biology
Additional features
• Osmoregulation
• Reproduction



Oviparity
Ovoviviparity
Viviparity
Feeding
Shark Orders
Order Lamniformes: mackerel sharks
Overview
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
Countercurrent heat exchange:
Great white shark
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
Order Lamniformes
Focus: basking sharks
Photos: D. Burton
Order Charcharhiniformes
Groundsharks: Overview
Photo: Paul Humann
Photo: Guillaume Chanfreau
Order Charcharhiniformes
Focus: Hammerheads
Photo: Guillaume Chanfreau
Order Charcharhiniformes
Focus: reef sharks (requim)
Order Orectolobiformes
Carpetsharks: Overview
Order Orectolobiformes
Focus: Wobbegongs
Order Orectolobiformes
Focus: Nurse sharks
Photos: Paul Humann
Order Orectolobiformes
Focus: Whale sharks
Photo: Werner Mischler
Order Heterodontiformes
Bullhead sharks
Horn shark
Photo: Tom Campbell, Innerspace VIsions
Order Hexanchiformes
Photos: Michigan Science Art
Bluntnose sevengill shark
Frill shark
Order Squaliformes
Dogfish sharks
Spiny dogfish
Photo: J. Stafford-Deitsch
Order Squaliformes
Cookie-cutter shark
Order Pristiophoriformes
sawsharks
Order Squatiniformes
Angel sharks
Skates and rays
Overview
Photos: Paul Humann
Order Rajiformes: skates
Order Torpediniformes
electric rays
Order Myliobatiformes
bat rays, stingrays, manta rays
Photo: Paul Humann
Photo: Andy Murch
Class Chondricthyes
Subclass Holocephali