Lab 12: Vertebrate Homologies

What are the four unique features of Chordata?

- Notochord -> develops into spine

- Dorsal Hollow Nerve Chord -> develops into brain and spinal chord

- Post-anal Tail

- Pharyngeal Slips -> develops into inner jaw/ear in vertebrates

What are the 5 clades of Vertebrates mentioned in the slides?

- Agnatha (jawless fishes)

- Osteichthyes (bony fishes); includes Actinopterygii and

Sarcopterygii

- Chondrichthyes (cartilaginous fishes)

- Amphibia (amphibians)

- Amniotes (snakes, lizards, crocodilians, birds, mammals, turtles)

What are the two clades of fishes mentioned in lab?

Cartilaginous fishes (Condrichthyes) and Bony fishes (Osteichthyes)

- sharks, skates, rays

- skeleton is made of cartilage

Cartilaginous fishes (Condrichthyes)

-Class: Sarcopterygii = lobe-finned fishes (lungfishes &

coelacanths)

•Swim bladder

-Class: Actinopterygii = ray-finned fishes (sturgeon, paddlefish, teleosts)

Bony fishes (Osteichthyes):

What are the two lineages that Actinopterygii splits into?

Chondrostei

- sturgeon & paddlefish

Neopteryii

- early group: bowfins & gars

- most recently derived group: teleosts (largest group in Actinopterygians)

What is a swim bladder used for in the class Sarcopterygii (lobe-finned fishes) ?

used for buoyancy regulation; gas exchange structure that likely evolved in air breathing tetrapods

- modern bony fishes

- within the class Actinopterygii (ray-finned)

- improved gas exchange mechanisms, efficient locomotor

and sensory structures, and buoyancy

- gills utilize counter-current exchange mechanism to extract 80-90% of oxygen in water

- lateral line allows for detection of vibrations

- Swim bladder no longer used for gas exchange; instead regulates gas to allows for buoyancy

- largest and most diverse group of ray-finned fishes

Teleosts

What is the difference between the swim bladder of the lobe-finned fishes (Sarcopterygii) and the ray-finned fish (Actinopterygii) ?

the lobe-finned fish (Sarcopterygii) possess a vascularized, lung-like swim bladder used primarily for breathing air, while ray-finned fish (Actinopterygii) have a modified, non-respiratory swim bladder used almost exclusively for buoyancy control

name the 5 types of fins found on a perch

- dorsal (anterior and posterior)

- pectoral

- pelvic

- anal

- caudel

What is the role of the operculum?

To protect the gills

Where is the lateral line and what does it do?

It is located on the side of the fish, it allows them to sense their surroundings

Another name for the lower jaw of a perch is the ______

mandible

A male perch will have how many gonads?

two

What is homology?

A characteristic shared by two species (or other taxa) that is similar because of common ancestry

- eg. forelimbs of vertebrates

Are all homologous structures used for the same function?

Homologous structures may or may not be used for the same function

What is an analogous structure?

Structures that serve the same function but are not derived from a common ancestral structure (structurally different)

- eg. flying