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Jawed Fishes

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Groups hide (from sharks) in caves during the day, travel up to 8km at night to forage. ... Tail heterocercal, like sharks. Ventral mouth (directed downward, ... – PowerPoint PPT presentation

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Title: Jawed Fishes


1
Jawed Fishes
  • Superclass Gnathostomata

2
Whats the big deal about jaws?
  • Allows grasping of objects
  • Makes herbivory possible
  • Can take bites and grind up food
  • Perhaps the greatest of all advances in
    vertebrate history was the development of jaws
    and the consequent revolution in the mode of life
    of early fishes.
  • Albert Sherwood Romer

3
How did jaws evolve?
  • Theory expansion of the third gill arch into a
    lower jaw
  • Butno fossil intermediates between jawless and
    jawed fishes to say for sure

4
Jawless fish
3rd Gill Arch
5
3rd gill arch enlarges and swings forward
6
Jawed Fish
7
Why did jaws evolve?
  • Old theory increased feeding efficiency
  • New theory jaws provide suction, which means
    better gill ventilation. Better feeding
    efficiency was a side effect.

8
Fish Systematics
  • Cladists consider there to be 8 classes in the
    phylum Chordata
  • 7 of these classes are fish!
  • 1 class contains some very old fish AND all other
    vertebrates

9
Traditional Systematics considers there to be 3
classes of fish
  • Kingdom Animalia
  • Phylum Chordata
  • Subphylum Vertebrata
  • Class Amphibia
  • Class Reptilia
  • Class Aves
  • Class Mammalia
  • Class Agnathajawless fish
  • Superclass Gnathostomata
  • Class Chondrichthyescartilaginous fish
  • Class Osteichthyesbony fish

This is the system we will use for this class (to
keep it simple!)
10
Superclass Gnathostomata
  • Extinct
  • Class Placodermi
  • Class Acanthodii
  • Living
  • Class Chondricthyes
  • Cartilaginous fishes
  • Class Osteichthyes
  • Bony fishes

11
Superclass Gnathostomata
  • Have jaws and paired fins
  • More complex vertebrae than Agnatha
  • Most numerous and diverse of vertebrate groups
  • 24,600 species named (may actually be around
    28,500)
  • Present in almost every imaginable aquatic habitat

12
Class Placodermi (extinct)
  • Covered in a
  • thick bony shield
  • Marine and freshwater species

13
Class Acanthodii (extinct)
  • Stout spines
  • Up to 6 pairs of ventrolateral fins

14
Class Chondrichthyes (living)Cartilaginous Fishes
  • Sharks
  • Rays
  • Ratfish
  • Much more later

15
Class Osteichthyes (living)Bony Fishes
  • All other fish

16
  • Class Osteichthyes
  • Subclass Sarcopterygii (lobe-finned)
  • Relict bony fishes
  • Coelacanths, lungfish
  • Subclass Actinopterygii (ray-finned)
  • Infraclass Chondrostei
  • Sturgeons, paddlefish
  • Infraclass Neopterygii
  • Gars, bowfin
  • Modern bony fishes, the teleosts
  • Remaining 22,000 or so species

17
General Characteristics
  • osteo bone
  • ichthyes fish
  • Bones in skeleton
  • Respiration by gills, covered by operculum
  • Mouth is usually terminal
  • Have jaws

18
Scale types of bony fishes
  • Cosmoid
  • Lungfishes and some fossil fishes only

19
Scale types of bony fishes
  • Ganoid
  • Shaped like a rhombus
  • Fit together with pegs and sockets
  • Bowfin, gars, paddlefish, sturgeons

Peg
20
Scale types of bony fishes
Cycloid
  • Cycloid and ctenoid
  • Most modern bony fish
  • Overlapping
  • Thin and flexible
  • Can count growth rings, like in a
  • tree stump

Ctenoid
21
Scaleless Fish
  • Less protection
  • More flexibility
  • Some catfishes and sculpins
  • Other fishes have scaleless heads

22
Subclass SarcopterygiiRelict Bony Fishes
  • Thought to be closely related to terrestrial
    vertebrates because of structure of limbs
  • Paired fins and lungs
  • Enamel on teeth
  • Lungfish (freshwater)
  • Coelacanths (marine)

23
Lungfishes
  • Two orders
  • Australia
  • South America and Africa
  • Long bodies
  • Continuous rear fins
  • Fins are fleshy
  • Lungs are modified swim bladders

24
Australian Lungfish
  • One species
  • Live in rivers that shrink to small pools in
    summer
  • Has one lung that supplements oxygen
  • Mainly breath through gills
  • Thought to have remained unchanged for 100
    million years

25
African and South American Lungfishes
  • 2 species
  • Have 2 lungs
  • Live in swamps that
  • dry up periodically
  • Dig burrows, line them with mucus, and estivate
    until it rains
  • During estivation, breath air through a small
    hole in burrow
  • When rain enters burrow, water enters gills and
    they awaken by coughing

26
Coelacanths
  • Thought to be extinct until one found in
    1938very exciting!
  • Life in the slow lane
  • 1.3 m long
  • Live up to 48 years, reproduce at 9 years
  • Longest known gestation period of any animal--3
    years

27
Groups hide (from sharks) in caves during the
day, travel up to 8km at night to forage. Do
headstands on the bottom.
28
Subclass Actinopterygii (ray-finned fish)
  • This subclass includes more old fish, and also
    all modern bony fish
  • Fins are not fleshy like the lungfish, but have
    hard rays instead
  • Infraclass Chondrostei
  • Infraclass Neopterygii

29
Infraclass Chondrostei
  • Old fish
  • Bottom-dwellers that eat invertebrates
  • Thought to be a link between sharks and bony fish
  • Skeleton more cartilaginous, like sharks
  • Tail heterocercal, like sharks
  • Ventral mouth (directed downward, under nose)
  • BUT operculum and some bone, like bony fish

30
Heterocercal Tail

Homocercal Tail

K.T. Shao
31
Infraclass Chondrostei
  • Order Polypteriformes
  • All live in Africa
  • Have multiple dorsal finlets
  • Ganoid scales
  • Fins are intermediate between ray fins and fleshy
    fins
  • Can live in stagnant water with low O2

--the bichirs
J. Moreau
32
Infraclass Chondrostei
  • Order Acipensieriformes
  • Family Acipenseridaesturgeons (23 species)
  • Skeleton mostly cartilaginous
  • Large bony plates on head
  • 3-30 feet long, 1300 lbs
  • Live up to 60 years
  • Valued for caviar
  • Eat worms, molluscs, crustaceans

33
Sturgeons
34
Infraclass Chondrostei
  • Order Acipenseriformes
  • Family PolyodontidaePaddlefish
  • 2 species one in U.S., one in China
  • 7 feet long, 250 lbs
  • Long snout is covered with tastebuds
  • Also valued for caviar
  • Polydon spathula present in WV

35
L. Lovshin
Paddlefish
L. Lovshin
36
  • Order Semionotiformes
  • Family Lepisosteidae--Gars
  • Diamond-shaped, non-overlapping ganoid scales
  • Heterocercal tail
  • To 9 feet, 220 lbs
  • 7 species, 2 in WVlongnose gar and shortnose gar
  • Predatory
  • Sluggish except when catching prey
  • Bony snout with lots of teeth

37
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38
  • Amiiformes
  • Family AmiidaeBowfin
  • 1 species
  • Present in WV
  • Shallow, weedy waters
  • Voracious predator
  • Can breath by gulping air
  • Thin layer of bone covers cartilaginous skull,
    otherwise skeleton is mostly cartilage

39
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40
Vocabulary
  • Tetrapod
  • Terminal mouth
  • Estivation
  • Heterocercal
  • Homocercal
  • Ventral
  • Dorsal
  • Lateral
  • Proximal
  • Distal
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