Part 3“Fishes” – an introduction

“Fishes”

Vertebrata

Figure 24.2Vertebrata

“Fishes”

Fish Diversityca. 25,000 described

species

482 families with living representatives

Largest > 12m

Smallest < 1cm

Largest > 12m

Smallest < 1cm

8,370m (27,455 feet) Deepest

Abyssobrotula galatheae 

Highest5,200m (17,000 feet)

Hottest

Coldest

up to 43.8° C (110.8°F)

-1.86° C (28.6°F)

Cyprinodon pachycephalus

Hypersaline

Cyprinodon variegatus

Up to 3x sea water

Torrential water

Colorado River Fishes

Trogloglanis pattersoni

Satan eurystomus

Caves

Anoxic water

Airbreathing

Diet

Reproduction

Life Spansseveral weeks

150+ years

Primitive and early fishes

Living jawless fishes = “agnatha”

Jawless Fishes (living)

Jawless Fishes (living)

Class Myxini

Hagfishes

We’re craniates, but not vertebrates

*distinct head, *tripartite brain *paired specialized sense organs *1 pair semicircular canals *glomerular kidney

*2 pairs semicircular canals*vertebrae

Craniate

Vertebrate

Habitat – Life History

Hagfishes at home

Slime glands and slime

Hagfish Eggs

Mxyine glutinosa L.

1 Family

6 generaca. 40 species

Class Myxinihagfishes

Physiology very ‘invertebrate-like’

Human interactions

Hagfish fishery

Eel Skin

Vertebrata

Vertebrates

Vertebrata

at least 2 semicircular canals

vertebrae

fancy, vertebrate physiology

Lampreys are vertebrates

Class CephalaspidomorphiLampreys

LampreysWe have vertebrae

2 families

6 genera

41 species

Lampreys

Class Cephalaspidomorphi

Lampetra tridentata

Local Diversity

Lampetra similis

Lampetra ayresi

Lampetra richardsoni

California Diversity (freshwater)

Predaceous lampreys

Brook lampreys

Predaceous or parasitic life mode

Predaceous lampreys

Brook lampreys

Lampreys nesting

Ammocoete

Lamprey ammocoete larva

Cephalochordate (amphioxus)

Craniate Origin?

Ammocoete

AmphioxusNiche + anatomy

Biodiversity and ConservationLampreys have an image problem

Great Lakes

and sea lampreys

Most Jawless fishes are fossil only

All sorts of fossil jawless fishes

Mineralized bone

Hagfishes and lampreys (living)

Fossil things – “Ostracoderms” and conodonts

†Condodonta

Earliest vertebrate ? (with bone)

†Condodonta

†Condodonta

earliest bone

†”Ostracoderms”

Fossil jawless fishes were more sophisticated that the surviving ones

Hagfishes and lampreys (living)

Fossil things

*Smallish

*Bony armor

*Internal cartilaginous skeleton

† “Ostracoderms”

*Mostly benthic

† “Ostracoderms” - niche

†”Ostracoderms” – 2 major radiations

More primitive

More advanced

Primitive ostracoderms

Advanced ostracoderms

Jawed vertebrates derive from “ostracoderms”

More advanced

on to creatures with jaws….

Jawed vertebrates

Early gnathostomes