FISHESBio II

Rupp

TYPES OF FISHES

Jawless Cartilaginous Bony

FISH CHARACTERISTICS

4 hallmarks of chordates

Sharks Lateral line Ampullae of

Lorenzini Operculum

Gills Tail types Scale types Fish musculature Swimming and the

swim bladder

TAXONOMY

Kingdom Animalia Phylum Chordata Subphylum Vertebrata

CLA

SS

MY

XIN

I

Hagfish

CLA

SS

CEP

HA

LO

SP

IDO

MO

RP

HI

Lampreys

CLA

SS

CH

ON

DR

ICH

TH

YES

Sharks, skates, and rays

CLA

SS

AC

TIN

OP

TER

YG

II

Ray-finned fishes

CLA

SS

SA

RC

OP

TER

YG

II

Lobe-finned fishes

CHORDATE HALLMARKS

Notochord Hagfishes and

lampreys keep this their entire lives

Made of thick-walled and fluid-filled cells pressed closely together

CHORDATE HALLMARKS

Dorsal hollow nerve cord Neural tube

formation Anterior becomes

the brain

CHORDATE HALLMARKS

Pharyngeal gill slits/pouches

CHORDATE HALLMARKS

FISH DEFINITION

For our purposes: A gill-breathing, poikilothermic (cold-blooded),

aquatic vertebrate that possesses fins and a skin that is usually covered in scales

Approximately 25,000 species Two basic body forms

Agnathans—jawless Gnathostomes—jawed

AGNATHANS

Cephalospidomorphi—lampreys—ectoparasites

Myxini—hagfishes—scavengers

SUPERCLASS GNATHOSTOMES

Cartilaginous fishes Class Chondrichthyes—approx. 850 species Subclass Elasmobranchii—sharks, skates,

and rays Dogfish anatomy

DOGFISH ANATOMY

DOGFISH ANATOMY

DOGFISH ANATOMY

GNATHOSTOME ADAPTATIONS

GNATHOSTOME ADAPTATIONS

GNATHOSTOME REPRODUCTIVE STRATEGIES

Internal fertilization Oviparous—some

species lay eggs immediately after fertilization

Ovoviviparous—retain the developing young in the uterus and they are nourished by yolk sacs

Viviparous—young are nourished by a placenta

SUPERCLASS GNATHOSTOMES

Bony fishes, aka osteichthyes Class Actinopterygii—ray-finned fishes Class Sarcopterygii—lobe-finned fishes

OSTEICHTHYES ADAPTATIONS

Operculum Tail types Skin and scales Musculature

Swimming Swim bladder Gills

OPERCULUM

A bony plate attached to a series of muscles running over the gills

Aid in more efficient respiration

Bernoulli’s Principle of Fluid Dynamics

TAIL TYPES

SCALE TYPES

Scales are embedded in the dermis and covered by the epidermis

Types Ganoid Cycloid Ctenoid Placoid

GA

NO

ID S

CA

LES

CTEN

IOD

SC

ALES

CYC

LO

ID S

CA

LES

PLA

CO

ID S

CA

LES

Typical in sharks

FISH MUSCULATURE

Myomeres-segments of the muscle

Myospeta—division point of the myomeres

Vertical septum and horizontal septum of body cavity

FISH MUSCULATURE

Red muscle or dark muscle is used in regular swimming

Red muscle is dark due to extra myoglobin and extreme vascularization

Red muscle is often referred to as the bloodline

White muscle for escape response

SWIMMING

Short muscular bodies and lunate tails for most efficient swimming

SWIM BLADDERS Maintain neutral

buoyancy and depth control

Balloon-like structure

Pulls gas out of the water to inflate

Two types Attached to gut—

ancient fishes Detached from gut—

more modern fishes Fish without swim

bladders: tuna, flounder, sharks, deep ocean fish

Sharks have a huge fatty liver to maintain neutral buoyancy

GILLS

Made of filaments called lamellae

Rich with blood vessels

Covered by operculum or gill slits

Counter current blood flow of blood and water increases efficiency—demonstration

Gill arches are the point of attachment for lamellae

Gill rakers remove debris from gills

Larger gill surface is often correlated with higher fish activity levels