Lecture Overview

I. Classification of Fishes

II. Fish Diversity

III. Body Shapes

IV. Scale Types

V. Fin Positions

Ostracoderms

Ordovician

Silurian

Devonian

Carboniferous

Permian

Triassic

Jurassic

Cretaceous

Tertiary

Placoderms

Chondrostei

Holosteans

Phylum

Subphylum

Superclass

Infraclass

Subclass

Division

Class

Superorder

Order

Chordata

Myxini Vertebrata

Ostracoderms Gnathostomata

Placodermi Chondrichthyes Acanthodii Osteichthyes

Holocephali Elasmobranchi Sarcopterygii Actinopterygii

Dipnomorpha

Actinistia

Tetropods Chondrostei Neopterygii

Teleostei

Galea Squalea

From:

Moyle and

Cech 2006

Fish Diversity There are ~31,000 fish species world wide, 26,000 are

known

Evolutionary lines with common characters: Jawless

fishes w/o vertebrae (Mixini), Jawless fishes

w/vertebrae(Cephalaspidomorpha) and Jawed fishes

(Gnathostomata) with cartelagenous and bony skeletons

Class Myxini (Jawless)

~ 40 species of hagfishes

Class Cephalaspidomorphi (Jawless)

~40 species of lamprey

Class Chondrichthes (Jawed-cartilagenous)

~800 species of sharks

~30 species of chimaeras

Class Osteicthyes (Jawed-bony)

~25,000 species of bony fishes

Agnathans

Ostracoderms

Ordovician

Silurian

Devonian

Carboniferous

Permian

Triassic

Jurassic

Cretaceous

Tertiary

Placoderms

Chondrostei

Holosteans

Agnathans (Ordivician) -Jawless

-lack of paired fins

-cartilagenous skeletons

-eel like bodies

Ostracoderms

Ordovician

Silurian

Devonian

Carboniferous

Permian

Triassic

Jurassic

Cretaceous

Tertiary

Placoderms

Chondrostei

Holosteans

Chondrichthyes: -Early Devonian Origin

-presently 800 species

-catilagenous skeleten

-no swim bladder

-internal fertilization(present forms)

-osmoregulation via urea

Ostracoderms

Ordovician

Silurian

Devonian

Carboniferous

Permian

Triassic

Jurassic

Cretaceous

Tertiary

Placoderms

Chondrostei

Holosteans

Osteichthyes -Early Devonian Origin ~25,000 species

-lungs

-bone skeleton

-bony scales

-lepidotrichia

Body Shapes

Rover-Predator

Lie-in-wait Predator

Surface-oriented

Bottom rover

Bottom clinger

Flatfish

Rattail

Deep-bodied

Eel-like

Rover-Predators

-streamlined shape -fins are evenly distributed

-pointed head - active and moving

-narrow caudal pedulcle

-forked tail -fusiform

Lie-in-wait Predators

-elongate body

-flattened head

-large mouth

-large caudal fin

-dorsal and anal fin placed far back

-narrow frontal profile

Bottom Roving Fishes

-flattened head

-semi-streamlined body

-enlarged pectoral fins

-sub-terminal mouth

-often have barbels

-may be fusiform, elongate or hemisperical

Bottom Clinging and Bottom Hiding Fishes

-usually small in size

-large flattened head

-large pectoral fins

-often modified pelvic fins (adhere to the bottom)

-may hide between and under rocks

-globiform, subcircular or hemispherical

Surface Oriented Fishes

-usually small in size

-upward pointing mouth (superior)

-dorsal fin located back on the body

-large eyes

-can utilize surface film oxygen in poor

conditions

Deep-bodied Fishes

-depth at least 1/3 length -compressiform

-long dorsal and anal fin

-pectoral fin located high on body

-pelvic fins usually directly below

-small mouth

-adapted for turning in small spaces

-have sacrificed speed for turning ability

Eel Like Fishes

-long elongate bodies

-wedge-shaped heads

-tapering or rounded tails

-long dorsal and anal fins

-pectoral fins relatively small

-body cross section compressed to round

-many live in cracks or burrow

-anguilliform

Flat Fishes

-depressiform

-are flattened either dorso-ventrally or laterally

-flounders and soles are essentially deep bodied fish that live on

their side, mouth often twisted to allow bottom feeding

- skates and rays are dorso-ventrally flattened and have

adaptations for respiration through the top of the head

Rattail Fishes

-large pointy heads

-large pectoral fins

-long, pointed tails

-almost all inhabit the deep sea

-usually scavenge dead fish

Types of Scales

Placoid scales

-small tooth like projections.

Ganoid scales

-contain ganoine, and are plate like.

Cycloid Scales

- composed of enamel (no ganoine) are

light and flexible. Found on many lower

teleosts. May have circuli and annuli

Ctenoid Scales

- composed of enamel -have ridges

called ctenii that my help with

hydrodynamics. May have circuli and

annuli

Placiod Scales

Found on Chondrichthyian fishes:

sharks, skates and rays.

Ganoid Scales

Found on Gars: Infraclass Chondrostei

Cycloid Scales

Found on Ostariophysians

Procanthopterygians among others:

Salmon, Pike,Smelt, Minnows

Ctenoid Scales

Found on higher teleosts: perch, sunfish,

temperate basses, drum etc.

External Structure

Caudal

Peduncle

Operculum

Dorsal Fin

Anal Fin Pelvic Fin

Pectoral Fin

Caudal Fin

Fins, Fin Positions and Shape

Tail Shapes

Lunate

Homocerical

Heterocerical