Osteichthyans (Boney Fish)

Osteichthyans

Overview of Osteichthyans

• Bony Fish
• Oste = "bony", Ichthyans = "fish"
• Hard ossified endoskeleton
• Group contains all tetrapods
• Operculum: A bony cover that protects fish gills
• Swim Bladder: air sac used to control buoyancy
• Evolved from lungs
• Mostly external fertilization

Fish Diversity

Ray-finned fishes

• Actinopterygii
• Over 27,000 species
• Major protein source for humans
• Fisheries have seriously depleted natural fish populations

Lobe-finned fishes

• Sarcopterygii
• Rod-shaped bones with thick layer of muscle in fins
• Likely used these robust fins to occasionally move on land
• Large predators in the Devonian era
• Only three lineages survived today
• Coelacanths: thought to be extinct 75 MYA, but found in 1938!
• Dipnoi: Lungfish
• Found in ponds and swamps
• Gulp air to supplement gills
• Can estivate when ponds are dry
• Tetrapods: Vertebrates with limbs and feet
• Far more diverse
• Includes humans!