Actinopterygian Relationships IBiology of Fishes
9.20.2012
Group Projects Intro Review (Craniate Relationships) Actinopterygian Relationships
Overview
Four General Categories (choose topic within 1 category) Evolutionary Patterns (evolution of specific species or
group; prehistoric fishes) Biology (morphology, form and function, physiology) Ecology (life history strategies, adaptations, behavior) Conservation (historical issues, overfishing, invasive
species, biodiversity loss, conservation methods) Include an example of current research in that area
Group Projects
4-5 people per group ~15 min presentation, written paper Sort into groups next Thursday (9.27) Select topic by week of October 8
Group Projects
Review:Craniate Relationships
Chondrichthyes
Osteichthyes
Sarcopterygii
Actinopterygii
Vertebrates
CRAN
IATE
S
Hagfishes Vertebrates
Lampreys Gnathostomes (possess jaws)
- Chondrichthyes (cartilaginous fishes)
- Osteichthyes (bony fishes)
Sarcopterygii (lobe-finned fishes)
Actinopterygii (ray-finned fishes)
Review:Craniate Relationships
Characteristics Possess a braincase (differentiates from tunicates and
cephalochordates) Other synapomorphies
Neural crest Complex sense organs & cranial nerves Muscularized gut wall, differentiated digestive organs Respiratory gills, heart, and hemoglobin Muscles to draw in water for feeding & respiration
Review:Craniate Relationships
Actinopterygian Relationships
Chondrichthyes
Osteichthyes
Sarcopterygii
Actinopterygii
Vertebrates
CRAN
IATE
S
Sarcopterygii (lobe fins)
Actinopterygii (ray fins)
- Cladistia (bichirs, reedfish)
- Chondrostei (sturgeons, paddlefishes)
- Neopterygii
-Holostei (gars, bowfins)
-Teleostei (teleosts, “modern fishes”)
Actinopterygian Relationships
Actinopterygii (Gr., aktin = ray + pteryg = wing or fin) Fins supported by flexible rays (muscle & bone inside) Teeth with enamel-like cap Scales covered by enamel-like tissue, ganoine (primitive
forms) Single dorsal fin Swim bladder connected to gut – can breathe air Spiral valve – aids in digestion Electroreception
Actinopterygian Relationships
Sarcopterygii (lobe fins)
Actinopterygii (ray fins)
- Cladistia (bichirs, reedfish)
- Chondrostei (sturgeons, paddlefishes)
- Neopterygii
-Holostei (gars, bowfins)
-Teleostei (teleosts, “modern fishes”)
Actinopterygian Relationships
Cladistia (Polypteriformes; bichirs, ropefish/reedfish) ~13 species Freshwater lakes, streams, swamps; tropical Africa Lobe-like base of pectoral fins, ganoid scales Obligate air-breather, two lungs Maxilla fused to head Long dorsal fin divided into finlets, each with a spine Electroreception
Actinopterygian Relationships
Cladistia (Polypteriformes)
Sarcopterygii (lobe fins)
Actinopterygii (ray fins)
- Cladistia (bichirs, reedfish)
- Chondrostei (sturgeons, paddlefishes)
- Neopterygii
-Holostei (gars, bowfins)
-Teleostei (teleosts, “modern fishes”)
Actinopterygian Relationships
Chondrostei (sturgeons and paddlefishes) Largely cartilaginous skeleton Fusion of jaw bones – maxilla, premaxilla, dermopalatine Loss of ganoid scales Electroreceptors
Actinopterygian Relationships
Sturgeons (Acipenseriformes) ~25 species Distribution restricted to northern hemisphere Some marine and some freshwater – lakes and large rivers All migrate into freshwater rivers to spawn Lake sturgeon (largest species in Great Lakes) 4 barbels, ventral sucking mouth, 5 rows of bony scutes Valuable caviar – Beluga sturgeon worth over $100,000
Chondrostei
Sturgeons (Acipenseriformes)
Paddlefishes (Acipenseriformes) 2 species – North American, Chinese Freshwater, large rivers – extirpated from Great Lakes Large paddle with electroreceptors Filter zooplankton from water column Chinese paddlefish different morphology, larger, and most
endangered fish in China (likely extinct)
Chondrostei
Paddlefishes (Acipenseriformes)
Sarcopterygii (lobe fins)
Actinopterygii (ray fins)
- Cladistia (bichirs, reedfish)
- Chondrostei (sturgeons, paddlefishes)
- Neopterygii
-Holostei (gars, bowfins)
-Teleostei (teleosts, “modern fishes”)
Actinopterygian Relationships
Neopterygii
Chondrichthyes
Osteichthyes
Sarcopterygii
Actinopterygii
Vertebrates
CRAN
IATE
S
Neopterygii (Holostei and Teleostei) Single independent skeletal support for each fin ray (dorsal
and anal fins); allows fins to be collapsed and spread more easily
Specialized musculature allows fins to move side to side Reduced heterocercal caudal fin 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) Debate of placement Group “resurrected” based
on new fossil evidence (2010)
Actinopterygian Relationships
Gars (Lepisosteiformes) 7 species North American distribution Primarily freshwater but can tolerate brackish and marine Elongated snout (ethmoid region), numerous teeth
(piscivorous) Thick ganoid scales Air-breathers Toxic eggs Largest freshwater fish in N.America
Holostei
Gars (Lepisosteiformes)
Bowfins (Amiiformes) Single species (Amia calva) Eastern North America Freshwater lakes and rivers Highly carnivorous; gular plate Males construct nest & guard young Long undulating dorsal fin, ocellus on tail Cycloid scales Air-breathers
Holostei
Bowfins (Amiiformes)
Sarcopterygii (lobe fins)
Actinopterygii (ray fins)
- Cladistia (bichirs, reedfish)
- Chondrostei (sturgeons, paddlefishes)
- Neopterygii
-Holostei (gars, bowfins)
-Teleostei (teleosts, “modern fishes”)
Actinopterygian Relationships II
Chondrichthyes
Osteichthyes
Sarcopterygii
Actinopterygii
Vertebrates
CRAN
IATE
S
Actinopterygian Relationships II
Teleostei (“modern fishes”) Caudal fin symmetrical – homocercal Uroneural bones in tail support upper lobe – both lobes Scales reduced – more flexible body Mobile premaxilla – suction feeding capabilities Advanced modes of locomotion and feeding, and therefore
success (~24,000 species)
Actinopterygian Relationships II