Actinopterygian Relationships I
Biology of Fishes
9.25.2012
Overview

Group Projects

Review (Craniate Relationships)
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Actinopterygian Relationships I
Group Projects

Four General Categories (choose topic within 1 category)

Evolutionary Patterns (evolution of specific species or
group; prehistoric fishes)
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Biology (morphology, form and function, physiology)
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Ecology (life history strategies, adaptations, behavior)
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Conservation (historical issues, overfishing, invasive
species, biodiversity loss, conservation methods)
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Include an example of current research in that area
Group Projects
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4-5 people per group

~15 min presentation, written paper

Sort into groups Thursday (9.27)

Select topic by week of October 8
CRANIATES
Review:
Craniate Relationships
Chondrichthyes
Sarcopterygii
Vertebrates
Osteichthyes
Actinopterygii
Review:
Craniate Relationships
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Hagfishes
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Vertebrates
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Lampreys
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Gnathostomes (possess jaws)
- Chondrichthyes (cartilaginous fishes)
- Osteichthyes (bony fishes)
Sarcopterygii (lobe-finned fishes)
Actinopterygii (ray-finned fishes)
Review:
Craniate Relationships

Characteristics
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Possess a braincase (differentiates from tunicates and
cephalochordates)
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Other synapomorphies
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Neural crest
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Complex sense organs & cranial nerves
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Muscularized gut wall, differentiated digestive organs
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Respiratory gills, heart, and hemoglobin
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Muscles to draw in water for feeding & respiration
CRANIATES
Actinopterygian Relationships
Chondrichthyes
Sarcopterygii
Vertebrates
Osteichthyes
Actinopterygii
Actinopterygian Relationships

Sarcopterygii (lobe fins)
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Actinopterygii (ray fins)
- Cladistia (bichirs, reedfish)
- Chondrostei (sturgeons, paddlefishes)
-Holostei (gars, bowfins)
-Teleostei (teleosts, “modern fishes”)
Actinopterygian Relationships
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Actinopterygii (Gr., aktin = ray + pteryg = wing or fin)
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Fins supported by flexible rays (muscle & bone inside)
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Teeth with enamel-like cap
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Scales covered by enamel-like tissue, ganoine (primitive
forms)
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Single dorsal fin
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Swim bladder connected to gut – can breathe air
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Spiral valve – aids in digestion
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Electroreception
Actinopterygian Relationships

Sarcopterygii (lobe fins)
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Actinopterygii (ray fins)
- Cladistia (bichirs, reedfish)
- Chondrostei (sturgeons, paddlefishes)
-Holostei (gars, bowfins)
-Teleostei (teleosts, “modern fishes”)
Actinopterygian Relationships

Cladistia (Polypteriformes; bichirs, ropefish/reedfish)
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~13 species
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Freshwater lakes, streams, swamps; tropical Africa
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Lobe-like base of pectoral fins, ganoid scales
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Obligate air-breather, two lungs
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Maxilla fused to head
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Long dorsal fin divided into finlets, each with a spine
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Electroreception
Cladistia (Polypteriformes)
Actinopterygian Relationships

Sarcopterygii (lobe fins)
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Actinopterygii (ray fins)
- Cladistia (bichirs, reedfish)
- Chondrostei (sturgeons, paddlefishes)
-Holostei (gars, bowfins)
-Teleostei (teleosts, “modern fishes”)
Actinopterygian Relationships

Chondrostei (sturgeons and paddlefishes)
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Largely cartilaginous skeleton
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Fusion of jaw bones – maxilla, premaxilla, dermopalatine
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Loss of ganoid scales
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Electroreceptors
Chondrostei
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Sturgeons (Acipenseriformes)
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~25 species
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Distribution restricted to northern hemisphere
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Some marine and some freshwater – lakes and large rivers
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All migrate into freshwater rivers to spawn
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Lake sturgeon (largest species in Great Lakes)
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4 barbels, ventral sucking mouth, 5 rows of bony scutes
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Valuable caviar – Beluga sturgeon worth over $100,000
Sturgeons (Acipenseriformes)
Chondrostei
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Paddlefishes (Acipenseriformes)
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2 species – North American, Chinese
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Freshwater, large rivers – extirpated from Great Lakes
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Large paddle with electroreceptors
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Filter zooplankton from water column
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Chinese paddlefish different morphology, larger, and most
endangered fish in China (likely extinct)
Paddlefishes (Acipenseriformes)
Actinopterygian Relationships

Sarcopterygii (lobe fins)
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Actinopterygii (ray fins)
- Cladistia (bichirs, reedfish)
- Chondrostei (sturgeons, paddlefishes)
Neopterygii
-Holostei (gars, bowfins)
-Teleostei (teleosts, “modern fishes”)
CRANIATES
Neopterygii
Chondrichthyes
Sarcopterygii
Vertebrates
Osteichthyes
Actinopterygii
Actinopterygian Relationships

Neopterygii (Holostei and Teleostei)
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Single independent skeletal support for each fin ray
(dorsal and anal fins); allows fins to be collapsed and
spread more easily
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Specialized musculature allows fins to move side to side
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Reduced heterocercal caudal fin
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Loss of electroreceptors (eventually re-evolved)
Actinopterygian Relationships

Sarcopterygii (lobe fins)

Actinopterygii (ray fins)
- Cladistia (bichirs, reedfish)
- Chondrostei (sturgeons, paddlefishes)
Neopterygii
-Holostei (gars, bowfins)
-Teleostei (teleosts, “modern fishes”)
Actinopterygian Relationships

Holostei (gars and bowfins)
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
Debate of placement
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Halecostomi
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Holostei
Group “resurrected”
based on new fossil
evidence (Grande 2010)
Holostei
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Gars (Lepisosteiformes)
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7 species
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North American distribution
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Primarily freshwater but can tolerate brackish and marine
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Elongated snout (ethmoid region), numerous teeth
(piscivorous)
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Thick ganoid scales
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Air-breathers
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Toxic eggs
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Largest freshwater fish in N.America
Gars (Lepisosteiformes)
Gars (Lepisosteiformes)
Human vs Gar vs Teleost Genomes
Gars (Lepisosteiformes)
Holostei
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Bowfins (Amiiformes)
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Single species (Amia calva)
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Eastern North America
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Freshwater lakes and rivers
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Highly carnivorous; gular plate
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Males construct nest & guard young
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Long undulating dorsal fin, ocellus on tail
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Cycloid scales
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Air-breathers
Bowfins (Amiiformes)
Actinopterygian Relationships

Sarcopterygii (lobe fins)

Actinopterygii (ray fins)
- Cladistia (bichirs, reedfish)
- Chondrostei (sturgeons, paddlefishes)
Neopterygii
-Holostei (gars, bowfins)
-Teleostei (teleosts, “modern fishes”)
CRANIATES
Actinopterygian Relationships II
Chondrichthyes
Sarcopterygii
Vertebrates
Osteichthyes
Actinopterygii
Actinopterygian Relationships II
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Teleostei (“modern fishes”)
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Caudal fin symmetrical – homocercal
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Uroneural bones in tail support upper lobe – both lobes
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Scales reduced – more flexible body
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Mobile premaxilla – suction feeding capabilities
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Advanced modes of locomotion and feeding, and
therefore success (~24,000 species)
Actinopterygian Relationships II