2Osteichthyes Means fish with bony skeletons There are over 20,000 species of bony fish
3Where Do Most Fish Live?Most fish live in the epipelagic zone
4Types of Fins Tail Fin (CAUDAL FIN) Paired Fins (PECTORAL and PELVIC FINS)Medial Fins (DORSAL and ANAL FINS)
5Rayed FinsRay-finned fish have fins supported by a fan-shaped array of bonesMakes the fin light, collapsible, and easy to moveRay-finned fishes are the most diverse group of living vertebrates, making up nearly half of all vertebrate species.
8Caudal Fins Caudal fins have different shapes 1. Homocercal --> Top and bottom halves the same sizea. 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
10Types of Caudal FinsHeterocercal – often found on sharks
11Nervous System Most fish have a complex sense of smell Used to detect prey, mates and predatorsSmell is detected in the nares (nostrils)Fish also have taste budsFound in the mouth, fins and skinCatfish have taste buds on barbels (whiskers)Rely on visionEyes focus by moving closer or further from the object they wish to viewCovered by a nictitating membrane – clear membrane that allows the fish to see while protecting the eye
12Fish SensesSight – some fish can see color and can see in very dim lightHearing – fish can hearSmell – fish have nostrils used for smellingTouch – fish can feel objects against their skinLateral line- A system of canals on the sides of fishes that helps fish detect changes in pressure, vibrations and currents
13Lateral LineFish “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!
14Functions of the Lateral Line Detect changes in pressure and vibrations and currentsDetect preySwim together in a schoolDetect predators on the side or behind themPick up vibrations from the swimming together of other animals
16Movement Most fish swim with an S motion A rhythmic side to side moving from the head to the tailControlled by bands of muscle called myomeresRun parallel along the sides of the fishVisible in fish you eatMakes up 75% of the fishes weightWhite muscle is used for bursts of speedRed muscle is used for constant locomotionThe fins are used like rudders to change direction in the waterSome fish move by moving only their fins and not their body
19Maintaining Buoyancy To maintain buoyancy the fish will either: Adjust the density of its body by using a SWIM BLADDERThey 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)
20SWIM BLADDERS A swim bladder is a balloon-like structure that is: inflated to make the fish rise higher in the wateror deflated to make the fish sink lower
22No Swim BladderSome fish like Tuna do not have a swim bladder and must swim fast to prevent sinkingSome fish like catfish do not have a swim bladder and spend their life on the bottom
23RespirationFish use gills to absorb oxygen from the surrounding water
24Parts of a GillGill Arch - stiff structure that supports the gill filaments and the gill rakersGill Rakers – prevent food from clogging up the gill filamentsGill Filaments – fingerlike projections where oxygen is absorbed and carbon dioxide is removed
26Excretion and Osmoregulation Marine fishesDrink constantlyLess blood is filteredWater is reabsorbedFreshwater fishesnever drinkLots of nephronsIons are reabsorbed
27Fish ReproductionMost 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.
28Fish Reproduction 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
29Fish Reproduction Includes: Courtship: a series of behaviors designed to attract matesSpawning: a release of gametes into the waterCopulation: a direct transfer of sperm into a females body
30Fish Reproduction Most fish reproduce by spawning. This is when the female swims and lays eggs on plants or sand in the waterThe male fish swims behind her depositing sperm into the water where some of it may land on and fertilize the eggs
31Fish ReproductionSome fishes are hermaphrodites. They have both male and female gonadsHermaphrodism is more common among the deep-water fishes. (Gourami)
32Fish Reproduction Sex Reversal Males may change to females or females to males (ex. Clownfish)
33Sex ReversalAmong 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.
34FeedingFish can be either carnivorous or herbivorous (mostly carnivorous)The teeth will tell you what they eatUsed for grasping and holding the preyPrey is usually swallowed wholeUsually have one preferred food sourceA type of fish, anemone, urchin, etc.Fish that feed on algae are called grazers
35Behavior Territoriality An established area that the fish protects against invadersSome are only territorial during mating period others are for lifeThought this helps ensure there is enough food for the fishDefended by aggressive behavior like making themselves appear larger or by chasing other fishFights are rare
36BehaviorSchooling4000 species of fish school at some point in their livesCan provide protection against predatorsCan cause confusionLess likely to be the one eaten if there are thousands of other fish around youCan increase swimming efficiency by reducing the drag of the waterCan be advantageous for mating or feeding
38Class Osteichthyes Characterized by having: Bone in their skeleton An operculum covering the gill openingsA swimbladder or lungsTrue scalesPaired finsHomocercal tail (Exception lungfish – diphycercal)Mouth terminalTwo chambered heartSexes separate (Sex reversal in some)Fertilization external for mostExcrete ammonia
39Class OsteichthyesThe bony fishes are the most diverse class of fish. ~24,000 speciesOsteichthyes are divided into two subclassesThe lobe-finned fish (Sarcopterygians)The ray-finned fish (Actinopterygians).*Most modern fish are members of the ray-finned, Teleost subdivision.
42SarcopterygiansSarcopterygians are the fish most closely related to modern amphibians, reptiles, birds, and mammals = terrestrial vertebratesThis 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
43Sarcopterygians Characteristics: Muscular lobe associated with fins Have lungs for gas exchangeLive in areas with seasonal droughtsCan breathe air if water stagnatesCan withstand desiccationBurrow in the mudHave enamel on the teeth
44SarcopterygiansCan survive drought by remaining in aestivation for 6 months or moreAestivation = dormant stateAfter rain fills the lake or riverbed Lungfish emerge from their burrows to feed & reproduce
58Actinopterygians The Teleosts Teleosts are modern day ray-finned fishUse their fins and body wall to push against water for locomotionSome secrete mucus to reduce frictionMost teleosts are carnivores swallowing prey wholeHerring & paddlefish are filter feedersTeleosts have pyloric ceca (outpockets in the small intestine to increase absorption)
59Ganoid Fish Scales Found on non-teleost bony fishes Usually diamond shaped bony scales“Heavy armor”Gars – Alligator Gar