Zoology lecture 14

What is the common name of Myxini?

Hagfish

How do Myxini get nutrition?

They are scavengers that feed on dead or dying fish by burrowing into carcasses and absorbing nutrients through their skin and mouth.

Do Myxini have jaws

No

What kind of fins do Myxini have?

Only median fins; no paired fins.

Do Myxini have skulls

Yes, they have a cranium made of cartilage.

Do Myxini have vertebral columns?

No, they have some rudimentary vertebrae but no true vertebral column

What is the notochord of Myxini made of?

Flexible cartilage-like tissue.

Do Myxini have scales?

No

Do Myxini have gill opercula

No, each gill opens separately to the outside.

What is the common name of Cephalaspidomorphi?

Lamprey

How do Cephalaspidomorphi get nutrition?

Many are ectoparasites that attach to fish with a suction mouth and rasping tongue to suck blood and body fluids; some are non-parasitic filter feeders

Do Cephalaspidomorphi have jaws?

No

What kind of fins do Cephalaspidomorphi have?

Only median fins (dorsal and caudal); no paired fins.

Do Cephalaspidomorphi have skulls?

Yes, they have a cartilaginous cranium.

Do Cephalaspidomorphi have vertebral columns?

yes made of cartilage

Do Cephalaspidomorphi have scales?

No

Do Cephalaspidomorphi have gill opercula?

No

Operculum

Bony flap that protects the gills

Myxini and cephalaspidomorphi are

Agnathans

Myxini have ___ chordate characteristics

5

Agnatha respire via

gill sacs

Anadromous

one that spends most of its adult life in saltwater but migrates to freshwater to spawn

barbels

Poorly-developed sense organs;

around mouth in myxini