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Questions and Answers
What is Andreolepis hedei?
What is Andreolepis hedei?
fossil of bony fish
What class do ray-finned fish belong to?
What class do ray-finned fish belong to?
Actinopterygii
Which group of fish achieved higher adaptive success than any other jawed fish?
Which group of fish achieved higher adaptive success than any other jawed fish?
Osteichthyes
Which two classes did the Osteichthyes split into early in their evolution?
Which two classes did the Osteichthyes split into early in their evolution?
What compound hardens the skeleton of most bony fishes?
What compound hardens the skeleton of most bony fishes?
Bony scales beneath a ______ cover their skin.
Bony scales beneath a ______ cover their skin.
How do most species of bony fishes reproduce?
How do most species of bony fishes reproduce?
They show ______ like that of sharks and an ______ covering their gills.
They show ______ like that of sharks and an ______ covering their gills.
What did the lungs of early Osteichthyes evolve into?
What did the lungs of early Osteichthyes evolve into?
What is the function of the swim bladder?
What is the function of the swim bladder?
What were the two sets of paired fins in the earliest bony fish?
What were the two sets of paired fins in the earliest bony fish?
What are the U-shaped series of bones connecting the fins to the skeleton called?
What are the U-shaped series of bones connecting the fins to the skeleton called?
What provides strength but a small range of motion to the pectoral girdle?
What provides strength but a small range of motion to the pectoral girdle?
How are the pelvic fins in modern bony fishes positioned?
How are the pelvic fins in modern bony fishes positioned?
What feature of the earliest bony fishes limited their range of motion?
What feature of the earliest bony fishes limited their range of motion?
What are the hardened struts that strengthened all fins called?
What are the hardened struts that strengthened all fins called?
What developed about the vertebral bodies?
What developed about the vertebral bodies?
What developed below the vertebral bodies?
What developed below the vertebral bodies?
What do the neural and haemal spines protect?
What do the neural and haemal spines protect?
What allows for finer motor control in fish?
What allows for finer motor control in fish?
The bony fishes evolved a more flexible fin and a ______.
The bony fishes evolved a more flexible fin and a ______.
What do the myomeres of bony fish increase?
What do the myomeres of bony fish increase?
What are some examples of Actinopterygii still in existence today?
What are some examples of Actinopterygii still in existence today?
In what infraclass are most bony fishes today classified?
In what infraclass are most bony fishes today classified?
What traits do teleosts share?
What traits do teleosts share?
Unlike sharks, the jaw of bony fish is at the anterior terminal end.
Unlike sharks, the jaw of bony fish is at the anterior terminal end.
What is the operculum?
What is the operculum?
What covers gills in bony fishes?
What covers gills in bony fishes?
What do the fin rays support?
What do the fin rays support?
What function do fin rays serve?
What function do fin rays serve?
What does homocercal mean?
What does homocercal mean?
How is the mouth of some fish described?
How is the mouth of some fish described?
A superior mouth is an adaptation for what?
A superior mouth is an adaptation for what?
What is located above the mouth of bony fish?
What is located above the mouth of bony fish?
The nostrils of bony fish are blind-ended.
The nostrils of bony fish are blind-ended.
What is inside the nostrils of bony fish?
What is inside the nostrils of bony fish?
What features are found behind the nostrils of bony fish?
What features are found behind the nostrils of bony fish?
What do the canals lined with sensory receptors of lateral lines detect?
What do the canals lined with sensory receptors of lateral lines detect?
What do the overlapping scales of bony fish get covered by?
What do the overlapping scales of bony fish get covered by?
What is the function of the mucous layer on fish scales?
What is the function of the mucous layer on fish scales?
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Study Notes
Overview of Ray-Finned Fish (Class Actinopterygii)
- Andreolepis hedei is a notable fossil representing bony fish.
- The class Actinopterygii encompasses all ray-finned fish.
- Osteichthyes, the bony fish group, achieved remarkable evolutionary success.
Evolutionary Diversity
- Osteichthyes diverged into two main classes:
- Actinopterygii (ray-finned fish)
- Sarcopterygii (lobe-finned fish)
Anatomy and Physiological Traits
- Bony fishes possess a skeleton reinforced with calcium phosphate (Ca3(PO4)2).
- Their skin is covered by bony scales beneath a mucous layer, aiding in protection and reducing drag in water.
- Most bony fish are oviparous, relying on external fertilization for reproduction.
Sensory and Protective Features
- Possess a lateral line system for detecting water pressure changes, similar to sharks.
- Operculum, a bony plate, shields the gills, enhancing protection.
- Early Osteichthyes likely had lungs that evolved into a swim bladder, essential for buoyancy control.
Fins and Movement
- The earliest bony fish had paired pectoral and pelvic fins connected by girdles, providing structural support.
- Modern bony fish have pelvic fins repositioned for improved swimming control.
- All fins are strengthened by lepidotrichia, or fin rays, allowing for flexibility and maneuverability.
Skeletal Structure
- Long neural and heal spines evolved to protect the spinal cord and dorsal aorta.
- Spinal enhancements created muscle separation, facilitating finer motor control.
Physical Adaptations
- The evolved homocercal (symmetrical) caudal fin supports better swimming agility.
- Myomeres arranged in a zigzag pattern amplify muscle contractions against the vertebral column.
Present-Day Ray-Finned Fish
- Modern ray-finned fish include sturgeon, gar, perch, and paddlefish.
- Most contemporary bony fishes belong to the teleostei infraclass, characterized by several distinctive traits.
Teleost Biology
- Teleosts exhibit circular, overlapping scales, homocercal tails, swim bladders, and advanced jaws enabling varied feeding strategies.
- Unlike sharks, the jaws of teleost fish are located at the anterior end for optimized surface feeding.
Sensory Structures
- Superior mouths adapted for surface feeding are complemented by blind-ended nostrils equipped with chemoreceptors for sensing chemicals in water.
- Large lidless eyes enhance visual capabilities, which are critical for survival.
Protective Features and Functionality
- Lateral line canals contain sensory receptors that detect minute water changes and bioelectric fields, improving awareness of surroundings.
- Scales overlap and are coated with a mucous layer to minimize friction and protect against pathogens.
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