Actinopterygian Relationships I · 2 species – North American, Chinese Freshwater, large rivers...

Actinopterygian Relationships I Biology 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

CR

AN

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

CR

AN

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

CR

AN

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

CR

AN

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