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

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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