Means fish with bony skeletons There are over 20,000 species of bony fish

Means fish with bony skeletons There are over 20,000 species of

bony fish

Most fish live in the epipelagic zone

1. Tail Fin (CAUDAL FIN)2. Paired Fins (PECTORAL and PELVIC

FINS)3. Medial Fins (DORSAL and ANAL

FINS)

Ray-finned fish have fins supported by a fan-shaped array of bones

Makes the fin light, collapsible, and easy to move

Ray-finned fishes are the most diverse group of living vertebrates, making up nearly half of all vertebrate species.

Caudal fins have different shapes1.  Homocercal --> Top and bottom halves the same size

a.      Rounded (Low A.R.)b.      Truncate (Intermediate A.R.)c.      Forked (Intermediate A.R.)d.      Lunate (High A.R.)

2. Heterocercal --> Top half different size than bottom half

Heterocercal – often found on sharks

Most fish have a complex sense of smell Used to detect prey, mates and predators Smell is detected in the nares (nostrils)

Fish also have taste buds Found in the mouth, fins and skin Catfish have taste buds on barbels

(whiskers) Rely on vision

Eyes focus by moving closer or further from the object they wish to view

Covered by a nictitating membrane – clear membrane that allows the fish to see while protecting the eye

Sight – some fish can see color and can see in very dim light

Hearing – fish can hear Smell – fish have nostrils used for

smelling Touch – fish can feel objects against

their skin Lateral line- A system of canals on the

sides of fishes that helps fish detect changes in pressure, vibrations and currents

Fish “hear” via their lateral lines, a line of pressure sensors running along each side of the fish that pick up pressure waves (= sound) in water. When someone pounds on an aquarium, that creates waves of pressure in the water that, to the fish, would be analogous to cupping your hands and pounding on your ears--NEVER POUND ON A FISH TANK!

Detect changes in pressure and vibrations and currents

Detect prey Swim together in a school Detect predators on the side or

behind them Pick up vibrations from the

swimming together of other animals

Most fish swim with an S motion A rhythmic side to side moving from the head to

the tail Controlled by bands of muscle called

myomeres Run parallel along the sides of the fish Visible in fish you eat Makes up 75% of the fishes weight White muscle is used for bursts of speed Red muscle is used for constant locomotion

The fins are used like rudders to change direction in the water Some fish move by moving only their fins and not

their body

To maintain buoyancy the fish will either: Adjust the density of its body by using a

SWIM BLADDER They will adjust the density of the

components of their insides (they will consume lighter weight ions and leave the heavier ones in the surrounding water)

A swim bladder is a balloon-like structure that is: inflated to make the fish rise higher in

the water or deflated to make the fish sink lower

Some fish like Tuna do not have a swim bladder and must swim fast to prevent sinking

Some fish like catfish do not have a swim bladder and spend their life on the bottom

Fish use gills to absorb oxygen from the surrounding water

Gill Arch - stiff structure that supports the gill filaments and the gill rakers

Gill Rakers – prevent food from clogging up the gill filaments

Gill Filaments – fingerlike projections where oxygen is absorbed and carbon dioxide is removed

Freshwater fishes never drinkLots of nephrons

Ions are reabsorbed

Marine fishesDrink constantly

Less blood is filtered

Water is reabsorbed

Most fish have internal sex organs that we cannot see.

fish gonads (sex organs) produce gametes (sex cells) only at certain times.

These times must be the same for both males and females and must be timed to the most favorable conditions.

Fish may only reproduce when there:

1. Is enough of the right kind of food2.There are enough hours of light each day3. The water is the right temperature

Includes: Courtship: a series of behaviors

designed to attract mates Spawning: a release of gametes

into the water Copulation: a direct transfer of

sperm into a females body

Most fish reproduce by spawning. This is when the female swims and

lays eggs on plants or sand in the water

The male fish swims behind her depositing sperm into the water where some of it may land on and fertilize the eggs

Some fishes are hermaphrodites. They have both male and female gonads

Hermaphrodism is more common among the deep-water fishes. (Gourami)

Sex Reversal Males may change to females or

females to males (ex. Clownfish)

Among some species of anemone fishes a single large female who mates only with a single large dominant male inhabits each sea anemone. All others are small non-breeding males. If the female disappears her mate changes into a female and the largest of the non-breeding males becomes the new dominant male. The new female can start spawning as soon as 26 days after her sex change.

Fish can be either carnivorous or herbivorous (mostly carnivorous) The teeth will tell you what they eat Used for grasping and holding the prey Prey is usually swallowed whole

Usually have one preferred food source A type of fish, anemone, urchin, etc.

Fish that feed on algae are called grazers

Territoriality An established area that the fish

protects against invaders Some are only territorial during mating

period others are for life Thought this helps ensure there is

enough food for the fish Defended by aggressive behavior like

making themselves appear larger or by chasing other fish

Fights are rare

Schooling 4000 species of fish school at some point

in their lives Can provide protection against predators

Can cause confusion Less likely to be the one eaten if there are

thousands of other fish around you Can increase swimming efficiency by

reducing the drag of the water Can be advantageous for mating or

feeding

Characterized by having: Bone in their skeleton An operculum covering the gill openings A swimbladder or lungs True scales Paired fins Homocercal tail (Exception lungfish –

diphycercal) Mouth terminal Two chambered heart Sexes separate (Sex reversal in some) Fertilization external for most Excrete ammonia

The bony fishes are the most diverse class of fish. ~24,000 species

Osteichthyes are divided into two subclasses

The lobe-finned fish (Sarcopterygians) The ray-finned fish (Actinopterygians).*Most modern fish are members of the ray-

finned, Teleost subdivision.

Sarcopterygians are the fish most closely related to modern amphibians, reptiles, birds, and mammals = terrestrial vertebrates

This subclass includes the lungfish and coelacanth. Coelacanth were thought to have become extinct at about the same time as the dinosaurs, until a live specimen was found in 1938

Characteristics: Muscular lobe associated with fins Have lungs for gas exchange Live in areas with seasonal droughts Can breathe air if water stagnates Can withstand desiccation Burrow in the mud Have enamel on the teeth

Can survive drought by remaining in aestivation for 6 months or more

Aestivation = dormant state

After rain fills the lake or riverbed Lungfish emerge from their burrows to feed & reproduce

Cosmoid scales

Ray-finned fish (Fins lack muscular lobes)

Have swimbladders to regulate buoyancy

~23,900 species

Include sturgeons and paddlefish Sturgeon eggs make caviar

Superorder Ostariophysi Order Cypriniformes (minnows, carps) Order Siluriformes (catfish) Superorder Protacanthopterygii Order Esociformes (pikes) Order Osmeriformes (smelts) Order Salmoniformes (salmon, trout,

whitefish) Superorder Paracanthopterygii Order Gadiformes (cod, hakes, pollock) Superorder Acanthopterygii Order Percoidei (perches, snook, basses) Order Pleuronectiformes (flounders, soles) Order Perciformes (mackerel, tuna,

swordfish)

Teleosts are modern day ray-finned fish Use their fins and body wall to push

against water for locomotion Some secrete mucus to reduce friction Most teleosts are carnivores

swallowing prey whole Herring & paddlefish are filter feeders Teleosts have pyloric ceca (outpockets

in the small intestine to increase absorption)

Found on non-teleost bony fishes

Usually diamond shaped bony scales

“Heavy armor” Gars – Alligator Gar

Found on teleost fishes

Light, thin, & flexible

Teleost fishes Have comblike

ridges along the exposed edge to reduce friction (drag)