Fish Biology

Subphylum Vertebrata

vertical column or spine

nerve cord into brain within cranium

endoskeleton of bone or cartilage

muscle system

closed circulatory system

complex organ systems

Family Petromyzontidae

Jawless Fishes

Hagfish and lamprey

Class Chondrichthyes

Cartliaginous fishes, elasmobranchs

5-6 gill openings

sharks, skates, rays, chimeras

Family Lamnidae

Mackerel sharks

heavy bodied, shark shaped

underslung jaw, large teeth

streamlined

crescent-shaped, nearly symmetrical caudal fin

large 1st dorsal and pectoral fins, anal fin present

fast swimming, partly “warm blooded”

Family Carcharhindiae

Requiem sharks

long, slender body

narrow, pointed snout

long, narrow pectoral fins

small 1st dorsal fin, small 2nd dorsal fin

heterocercal tail

counter shading

Family Squalidae

dogfish sharks

small bodied, shark shaped

no anal fin

1st dorsal entirely in front of pelvic fins

spine at front of each dorsal fin

Family Rajidae

skates

dorso-ventrally flattened

rhomboid to circular disk-shaped body

spines on body and tail

Family Chimaeridae

ratfishes

short, blunt nose

rabbit-shaped head

flat crushing teeth

prominent lateral line on slippery skin

large triangular pectoral fin

large green eyes

white spots

long tapering tail

Superclass Osteichthyes

bony fish

Family Acipenseridae

sturgeons

cartilaginous skeleton

heterocercal tail

sub-terminal mouth

5 rows of dermal scutes

Division Teleostei (Teleosts)

all remaining fish

“perfect bone”

most fish we encounter

moveable jaw

spine ends in caudal peduncle

homocercal caudal fin (equal)

Family Clupeidae

herring and shads

laterally compressed

silvery, countershaded

1 short dorsal fin

deeply forked caudal fin

no adipose fin

no spines

scutes on belly

Family Engraulidae

achovies

small, silvery

long snout overhangs, large mouth (inferior jaw)

upper jaw extends past eye

filter feeders

similar to herrings

Family Salmondiae

salmon, trout, charr

adipose fin behind 1st dorsal

low pectoral fins

pelvic fins abdominal

no spines in fins

square caudal fin

Family Osmeridae

smelts

small, frail

adipose fin

short dorsal fin at mid-body

pelvic fins andominal

coutershaded

Family Gadidae

cods

elongate

3 dorsal fins, 2 anal fins

pelvic fins thoracic

no fin spines

barbels on chin

sub-terminal mouth

Family Merlucciidae

hakes

2 dorsal fins, 2nd long and notched

v-shaped ridge on top of head

no chin barbel

lower jaw projects slightly

Family Atherinopsidae

silversides

topsmelt, jacksmelt, don’t confuse w/ true smelts

2 dorsal fins, no adipose fin

bright silver stripe along side

small mouth

no lateral line

Family Syngnathidae

pipefishes and seahorses

encased in bony rings

body rigid, very long and slender

no pelvic fin

small, toothless mouth at end of tube snout

Family Gasterosteidae

sticklebacks

small mouth

armored w/ bony plates instead of scales

Family Scorpaenidae

rockfishes and their relatives

very spiny, some venomous

stout body

live-bearers, ovoviviparous

Family Cyclopteridae

limpfishes

related to snailfishes

modified pelvic fins form sucker disk

globular shape

covered w/ conical plates

Family Liparidae

snailfishes

pelvic fins modified into sucking disk

soft bodied

dorsal and anal fin joined to caudal fin

similar to clingfishes

Family Hexagrammidae

greenlings

no spiny head

elongate body w/ single dorsal fin

pelvic fins thoracic

Family Cottidae

sculpins

stout, round body

large head w/ spines, knobs or cirri

large, fan-like pectoral fins

dorsal, anal fins usually long

brown coloration, some green

Family Emriotocidae

surfperches

laterally compressed, eliptical

un-notched dorsal fin

live-bearers, viviparous

Family Stichaeidae

pricklebacks

eel-like

dorsal fin has all spines (prickly)

anal fin longer than 50% of body

Family Pholidae

gunnels

eel-like, long compressed body

dorsal fin long and flexible

anal fin < 50% body length

Family Goniesocidae

clingfishes

sucking disk on ventral surface

no scales

no fin spines

dorsal fin opposite anal fin, far back

tadpole appearance

Family Clinidae

kelp bunnies

long single dorsal fin w/ raised sections at each end

forward pelvic fin w/ 1 spine and 3-4 rays

Family Goniidae

gobies

small fish

pelvic fins fused to form cone

1st dorsal fin w/ 7 spines

rounded caudal fin

smallish gill openings

Family Scombridae

mackerels and tunas

two dorsal fins w/ 5-12 finlets behind 2nd dorsal and anal fins

pectoral fins high on body

slender caudal peduncle w/ 2 keels

specialized subcutaneous vascular system in some

Family Paralichthyidae

sand flounders

flat

both eyes on left side

lateral line arches over pectoral fin

Family Pleuronectidae

right eye flounders

flat

eyes on right side

FIns

Median fins: dorsal, anal, adipose, caudal

Paired fins: pectoral and pelvic

Lateral Line

used in detection of predators/prey

water enters pores,, signals to fish

Estuary Types Based on Formation

coastal plain/drowned river mouth estuary

tectonic estuary

bar-built estuary

fjords

Estuary Types Based on Circulation and Salinity

salt wedge (deep w/ shallow mouth, large flow of FW)

partially-mixed; two-layer (shallow, moderate FW volume)

well-mixed (shallow, low FW)

highly stratified fjord (deep, stagnant SW collected deep)

Adaptance to Estuaries

broad tolerance

regulating physiology

behaviorally choosing suitable environment

r-strategists

generalists

Saltmarsh Community

mainly Marsh grasses

traps nutrient-rich sediments, less eutrophication

tidally-ephemeral habitat

vertical zonation

Seagrass Beds

shallow, marine grasses

reduce velocity of currents, increase sedimentation

increase habitat complexity

Oyster Reefs

subtidal reefs in estuaries

filter-feeders remove plankton from water

influence water clarity

Soft Sediment Habitats (Mudflats)

habitat for many invertebrates

food base for fishes and birds

Open Water Community Within Estuaries

high production and biomass at intermediate salinities

benthic filter-feeders profit from plankton production

high settling of plankton in plumes: death zones

Types of Estuary Fishes

freshwater

diadromous (anadromous, catadromous)

true estuarine

marine migrants

marine