The Ray-Finned Fish (Actinopterygii) Flashcards

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Questions and Answers

What is Andreolepis hedei?

fossil of bony fish

What class do ray-finned fish belong to?

Actinopterygii

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?

Actinopterygii and Sarcopterygii Signup and view all the answers

What compound hardens the skeleton of most bony fishes?

calcium phosphate, Ca3(PO4)2 Signup and view all the answers

Bony scales beneath a ______ cover their skin.

mucous layer Signup and view all the answers

How do most species of bony fishes reproduce?

oviparous with external fertilization Signup and view all the answers

They show like that of sharks and an covering their gills.

lateral line system, operculum Signup and view all the answers

What did the lungs of early Osteichthyes evolve into?

swim bladder Signup and view all the answers

What is the function of the swim bladder?

water buoyancy in the water column Signup and view all the answers

What were the two sets of paired fins in the earliest bony fish?

pectoral and pelvic Signup and view all the answers

What are the U-shaped series of bones connecting the fins to the skeleton called?

girdles Signup and view all the answers

What provides strength but a small range of motion to the pectoral girdle?

connected to the skull Signup and view all the answers

How are the pelvic fins in modern bony fishes positioned?

shifted forward Signup and view all the answers

What feature of the earliest bony fishes limited their range of motion?

broad bases of the fins Signup and view all the answers

What are the hardened struts that strengthened all fins called?

lepidotrichia or fin-rays Signup and view all the answers

What developed about the vertebral bodies?

long neural spines Signup and view all the answers

What developed below the vertebral bodies?

heal spines Signup and view all the answers

What do the neural and haemal spines protect?

spinal cord and the dorsal aorta Signup and view all the answers

What allows for finer motor control in fish?

spines separating the muscles on the right and left sides Signup and view all the answers

The bony fishes evolved a more flexible fin and a ______.

homocercal (symmetrical) caudal fin Signup and view all the answers

What do the myomeres of bony fish increase?

the force exerted on the vertebral column with each contraction Signup and view all the answers

What are some examples of Actinopterygii still in existence today?

sturgeon, gar, perch and paddlefish Signup and view all the answers

In what infraclass are most bony fishes today classified?

teleostei Signup and view all the answers

What traits do teleosts share?

circular, overlapping scales, homocercal caudal fins, a swim bladder, and a complex jaw Signup and view all the answers

Unlike sharks, the jaw of bony fish is at the anterior terminal end.

True Signup and view all the answers

What is the operculum?

bony plate created by ossification of the dermis Signup and view all the answers

What covers gills in bony fishes?

operculum Signup and view all the answers

What do the fin rays support?

two dorsal fins Signup and view all the answers

What function do fin rays serve?

support and protection from predators Signup and view all the answers

What does homocercal mean?

meaning that the top and bottom are symmetrical Signup and view all the answers

How is the mouth of some fish described?

superior (faces upward) Signup and view all the answers

A superior mouth is an adaptation for what?

feeding at or near the surface Signup and view all the answers

What is located above the mouth of bony fish?

a pair of nostrils Signup and view all the answers

The nostrils of bony fish are blind-ended.

True Signup and view all the answers

What is inside the nostrils of bony fish?

chemoreceptors Signup and view all the answers

What features are found behind the nostrils of bony fish?

large lidless eyes Signup and view all the answers

What do the canals lined with sensory receptors of lateral lines detect?

slight changes in water current, temperature and bioelectric fields Signup and view all the answers

What do the overlapping scales of bony fish get covered by?

a mucous layer Signup and view all the answers

What is the function of the mucous layer on fish scales?

cuts down on water resistance and protects from pathogens Signup and view all the answers

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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Description

Test your knowledge with these flashcards about the Ray-Finned Fish, which fall under the class Actinopterygii. Explore key terms and definitions related to the evolution and classification of these fascinating bony fish. Perfect for students and enthusiasts alike!