Overall Characteristics Ectothermic Body temp. changes with the temp. of the surroundings “Cold-Blooded’ Gills Used to breathe – water into mouth & out gills

Scales Protect the body Slime Layer - Protects against bacteria and viruses

Fins - for swimming

Lateral Line Runs along each side of body. Important sense organ that detects water movement and pressure

External Fish Anatomy

Internal Fish Anatomy

SPAWNING The process of spawning typically involves females releasing eggs into the water, while males release sperm (milt) to fertilize the eggs.

Fish Reproduction There are two main reproduction methods in fish. The first method is by laying eggs and the second by live- bearing (producing their young alive).

Livebearers

Fish Reproduction Most fishes are egg-layers, but many bear living young. Live- bearing fishes may be ovoviviparous, in which the eggs essentially simply hatch within the female Over 97% of all known fish are oviparous, that is, the eggs develop outside the mother's body.

Fish Reproduction Viviparous, in which the unborn young are supplied nourishment through the mother's tissues. Giving birth to living offspring that develop within the mother's body.

Fish Reproduction In the most common form, heterosexual reproduction, there are separate male and female parents.

Fish Reproduction In hermaphroditic reproduction, a single fish is both male and female, produces both eggs and sperm (either at the same time or at different times).

Some hermaphrodites: both male & female gonads Simultaneous herma – male & fem. systems present at same time Sea Bass Sequential herma – 1st one sex, then the other Barramundi

Fish Reproduction In parthenogenetic reproduction, unfertilized eggs develop into embryos.

Fish Reproduction Abandon the eggs. Build nests and care for both the eggs and newly hatched young. Carrying the eggs

Male & Female Mandarin Fish REPRODUCTION REPRODUCTIVE SYSTEM Usually separate sexes Male & Female Mandarin Fish

Wrasse

Grunion (Pacific Coast) Produce gametes at certain time; triggered by day length, temp, availability of food, tides etc. Grunion (Pacific Coast)

Grunion Run

3 CLASSES OF FISH Class Agnatha No jaws, no scales Skeleton of cartilage Primitive fish Ex: lampreys, hagfish

Class Chondrichthyes Skeleton of cartilage Rigid fins Gill slits Ex: sharks, rays

Class Osteichthyes Skeleton of bone Gill covering = operculum Swim bladder (helps float) Ex: bony fish

BEHAVIOR Used to: Adapt to light & currents Find food/shelter; avoid enemies Court & reproduce

TERRITORIALITY Home areas defended against intruders; crowded envs w/limited resources Clown fish guarding her anemone

Aggressive behaviors = bluffing Raised fins, open mouth, rapid darting

Sounds – grinding teeth, drum bladders Croaker Alone, male & female, groups

SCHOOLING Throughout life: herring, mackerel

Part-time: as juvenile; for feeding

Usually same size; perfect unison Protection Increase swimming efficiency Feeding/Mating

MIGRATION Mass movement from one place to another

Why? Feeding- Ex: tuna Atlantic blue finned tuna

Reproduction Anadromous – SW; FW to breed Salmon

Catadromous – FW; SW to breed Eel

FEEDING Most carnivorous

ADAPTATIONS Attackers – streamlined, quick bursts of speed, sharp teeth curved backwards

Sit & Wait – camouflaged, partially bury Lizardfish

STARGAZER

Aggressive mimicry - modified spine on head to lure small fish Splitlure frogfish

Frogfish

DEEP SEA ANGLER FISH

Suctorial feeders – tubelike snouts & small mouths Pipefish

Seahorse

Forceps Butterflyfish

Grubbers - bottom feeders w/downward mouth, Grubbers - bottom feeders w/downward mouth, barbels to detect buried prey (crust/worms)

Grazers – continual browsing like sheep/cows Coral eaters w/beak-like mouth Parrotfish

Plankton eaters swim w/open mouth, trap plankton on gill rakers

Northern Anchovy