Icthyology Lec 1

What are the 5 broad characteristics of a fish?

-Poikilothermic

-vertebrate

-paired fins

-gills

-scales

What are the three major groups of living fishes?

-Cyclostomes (jawless fishes)

-Chondrichthyes (cartilaginous fishes)

-Osteichthyes (Bony fishes)

What two orders make up the cyclostomes?

-Myxini (Hagfishes)

-Petromyzontida (Lampreys)

What two orders make up chondricthyes?

-Elasmobranchii (sharks, skates, and rays)

-Holocephali (Chimeras)

What two orders make up Osteichthyes?

-Sarcopterygii (lobe finned fishes)

-Actinopterygii (Ray finned fishes)

Characteristics of Myxini (Hagfishes)?

They have no vertebrae, paired fins, jaws, or scales.

Characteristics of Petromyzontida (lampreys)?

-Have vertebrae.

-Do not have jaws, paired fins, or scales.

Chondrichthyes characteristics?

-Cartilaginous fishes

-No bones

-Have jaws and paired fins

-Placoid scales

What is an apomorphic characteristic?

A derived characteristic

What is a plesiomorphic characteristic?

Ancestral

Synapomorphies are?

Shared derived characters

autapomorphies are?

Characters that define single taxa

Characteristics of Osteichthyes?

-Ray finned modern fishes

-jaws and paired fins

-Bony skeleton and flattened scales

A monophyletic group includes?

One group (clade)

A paraphyletic group includes?

Most of one group

A polyphyletic group includes?

Mixed groups