Vertebrates - Bony Fishes Flashcards

Questions and Answers

Why is the Devonian important in the case of fishes?

All major lineages of fishes, including extant and extinct species, coexisted during the Devonian.

What are Osteichthyes? What are its two groups?

Bony fish; its two groups are Sarcopterygii and Actinopterygii.

When do teleosts appear?

During the Mesozoic era.

When were Sarcopterygii and Actinopterygii diverse?

Sarcopterygii were most diverse during the Devonian, while Actinopterygii diversified during the Triassic period. Signup and view all the answers

What are some basic differences between bony fish and cartilaginous fishes?

<ol> <li>Cartilaginous fishes are all marine; bony fish are in marine and freshwater. 2. Cartilaginous fishes often have fusiform shapes; bony fish are usually bilaterally flattened. 3. Bony fish have endochondral bone. 4. Bony fish have smooth scales. 5. Bony fish do not have a spiracle. 6. Bony fish have external fertilization and lay a large number of eggs.</li> </ol> Signup and view all the answers

What are the 5 unique characteristics of bony fish?

<ol> <li>Fully ossified skeleton. 2. Dermal bone surrounds the braincase. 3. Dermal jaw bones bear teeth. 4. Operculum flap over gills. 5. Gas bladder for respiration and buoyancy.</li> </ol> Signup and view all the answers

How does the operculum increase respiratory efficiency in bony fish?

It creates suction to draw water across the gills and out the gill slits. Signup and view all the answers

How does the gas bladder help with buoyancy? What is it called when it serves this function?

It is called the swim bladder; it helps with buoyancy by allowing fish to adjust gas volume. Signup and view all the answers

What is a synapomorphy of Sarcopterygii?

They have robust, lobed fins supported by endochondral bones. Signup and view all the answers

In lobed-finned fishes, what is the function of the gas bladder? What other structures assist in this function?

The gas bladder functions for respiration; both lungs and gills assist in this function. Signup and view all the answers

What is the difference between the tails of ancestral and modern lobe-finned fishes?

Ancestral forms had heterocercal tails, while modern forms have a diphycercal type. Signup and view all the answers

Give an example of fishes with a heterocercal, homocercal, and diphycercal tail type.

Heterocercal: extant sharks and extinct lobe-finned fish; Homocercal: ray-finned fishes; Diphycercal: extant lobe-finned fishes. Signup and view all the answers

Why is the Australian lungfish important? How is it different than other living lungfish?

It is important due to its unique respiratory adaptations; it differs from other lungfish by having distinct anatomical features. Signup and view all the answers

Study Notes

Importance of the Devonian Period

The Devonian is known as the "age of fishes."
Major fish lineages coexisted, including hagfish, lampreys, conodonts, ostracoderms, placoderms, Chondrichthyes, and Osteichthyes.

Osteichthyes Overview

Osteichthyes refers to bony fish.
Divided into two groups: Sarcopterygii (lobe-finned, includes tetrapods) and Actinopterygii (ray-finned, dominant with over 33,000 species).

Emergence of Teleosts

Teleosts appeared during the Mesozoic era, not present in the Devonian.
Today, teleosts constitute approximately 98% of living fish species.

Diversity of Bony Fish Groups

Sarcopterygii thrived during the Devonian.
Actinopterygii diversified in the Triassic period of the Mesozoic era, coinciding with the emergence of teleosts.

Differences Between Bony Fish and Cartilaginous Fishes

Bony fish inhabit both marine and freshwater environments; cartilaginous fishes are strictly marine.
Shape variations: sharks are fusiform; bony fish are often bilaterally flattened.
Bony fishes have endochondral bone in their vertebrae and skeleton; cartilaginous fishes do not.
Smooth scales characterize bony fish, contrasting with rough placoid scales of cartilaginous species.
Bony fish lack spiracles and reproduce via external fertilization, laying large numbers of eggs.

Unique Characteristics of Bony Fish

Fully ossified skeleton made of endochondral bone, including vertebrae and appendages.
Dermal bone encases the braincase.
Dermal jaw bones contain teeth.
Bony operculum covers gills, enhancing respiratory efficiency and protecting gill tissue.
Gas bladder present for respiration, buoyancy, or both.

Operculum Functionality

Operculum generates suction to draw water across the gills, improving oxygen extraction efficiency.
Reduces reliance on ram ventilation, which is common in sharks.

Swim Bladder and Buoyancy

The gas bladder, or swim bladder, aids in buoyancy; fish adjust gas volume for neutral buoyancy.
Fish fill the swim bladder via capillary networks drawing oxygen from the bloodstream, adjusting as they change depth.

Synapomorphy of Sarcopterygii

Lobed fins are supported by endochondral bones, a distinct trait of Sarcopterygii.

Gas Bladder Function in Lobed-Finned Fishes

In lobed-finned fishes, the gas bladder primarily supports respiration; early forms had both lungs and gills.
Modern lungfish retain both structures, with the exception of the coelacanth, which lacks lungs.

Tail Structure Variations

Ancestral lobe-finned fishes had heterocercal tails; modern forms feature diphycercal tails.
Heterocercal tail example: extant sharks and extinct lobe-finned fishes.
Homocercal tail: ray-finned fishes.
Diphycercal tail: extant lobe-finned fishes.

Australian Lungfish Significance

The Australian lungfish is crucial for understanding evolutionary biology due to its unique adaptations compared to other lungfish species.

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Description

Explore the essential concepts of bony fishes, including their evolution during the Devonian period, and the classification of Osteichthyes. This quiz focuses on key definitions and significant groups within the bony fish lineage. Perfect for anyone studying vertebrate biology or ichthyology.