Fishes

Question 1

Class Myxini

Answer 1

Hagfishes:

• No jaws
• Circular mouth WITHOUT horny teeth
• No paired appendages
• Vestigial eyes
• External gill slits

Question 2

Class Petromysontiformes

Answer 2

Lampreys:

• No jaws
• Sucker mouth with horny teeth
• No paired appendages
• External gill slits

Question 3

Subclass Elasmobranchii

Answer 3

Sharks and Rays:

• External gill slits
• Spiracle
• Heterocercal tail
• Ancestral placement of fins (pectoral low on body, pelvic near cloacal opening)
• One pair of claspers on male
• Placoid scales

Question 4

Subclass Holocephali

Answer 4

Chimaera:

• Fleshy operculum covering gills (one external opening on each side)
• Two pairs of claspers on male

Question 5

Subclass Chondrostei

Answer 5

Sturgeon and relatives:

• Fleshy operculum covering gills (one external opening each side)
• Two pairs of claspers on male

Question 6

Infraclass Holostei

Answer 6

Bowfin (Amia) and gars:

• Actinotrichia
• Bony operculum (One external on each side)
• Abbreviated hetercercal tail
• Intermediate placement of fins (pectorals higher and pelvics shifted anteriorly to about half-way between anus and operculum)
• Bony scales

Question 7

Infraclass Teleostei

Answer 7

Perch and most other fish:

• Actinotrichia
• Bony operculum (one external opening on each side)
• Homocercal tail
• Derived placement of fins (Pectorals high on side of body, pelvics nearly as far forward as pectorals)
• Bony scales