Fig. 8.17

I.Fishes - Biology F.Regulation of Internal Environment 1.Chondrichthyes Concentration of solutes in blood similar to seawaterConcentration of solutes in blood similar to seawater Retain urea in blood (toxic to most other vertebrates)Retain urea in blood (toxic to most other vertebrates) Absorb water through gills and skinAbsorb water through gills and skin Salts excreted by kidneys and rectal glandSalts excreted by kidneys and rectal gland 2.Osteichthyes Concentration of solutes much lower than seawaterConcentration of solutes much lower than seawater ~14 ‰ vs. ~35 ‰~14 ‰ vs. ~35 ‰ Drink seawaterDrink seawater Salts excreted by kidneys and chloride cells in gillsSalts excreted by kidneys and chloride cells in gills Kidneys produce small amounts of urineKidneys produce small amounts of urine

Fig. 8.18

I.Fishes - Biology G.Sensory Systems 1.Smell/Taste Most fishes have a highly developed sense of smellMost fishes have a highly developed sense of smell Detect food, mates, predators, navigational informationDetect food, mates, predators, navigational information Sensory cells in olfactory sacs on both sides of headSensory cells in olfactory sacs on both sides of head Sacs connected to outside through nares (nostrils)Sacs connected to outside through nares (nostrils) Sharks especially sensitive to scent of blood (1 ppm)Sharks especially sensitive to scent of blood (1 ppm) Salmon locate home stream by scent (imprinting)Salmon locate home stream by scent (imprinting) Taste with taste buds in mouth and on lips, fins, skin, barbelsTaste with taste buds in mouth and on lips, fins, skin, barbels 2.Lateral line Clusters of sensory cells (neuromasts) in small canals lining head and along sides of bodyClusters of sensory cells (neuromasts) in small canals lining head and along sides of body Sensitive to vibrations in waterSensitive to vibrations in water Used for orientation, detection of prey and currents, avoidance of predators and obstaclesUsed for orientation, detection of prey and currents, avoidance of predators and obstacles

Fig. 8.19

I.Fishes - Biology G.Sensory Systems 3.Electroreception Found in ChondrichthyesFound in Chondrichthyes Ampullae of LorenziniAmpullae of Lorenzini Detection of prey, navigationDetection of prey, navigation Extremely sensitive (may be less than 1 nV/cm)Extremely sensitive (may be less than 1 nV/cm) Can detect a marine mammal’s electric field 3 m awayCan detect a marine mammal’s electric field 3 m away Used in combination with other sensesUsed in combination with other senses 4.Inner ears Calcareous otoliths rest on sensory hairsCalcareous otoliths rest on sensory hairs Detect sound waves + changes in fish attitudeDetect sound waves + changes in fish attitude Help to maintain equilibrium and balanceHelp to maintain equilibrium and balance Can be used to determine age of fishCan be used to determine age of fish

II.Fishes - Behavior A.Schooling Displayed by ~4000 speciesDisplayed by ~4000 species Some fishes school throughout life, others only when juveniles, feedingSome fishes school throughout life, others only when juveniles, feeding School sizes varySchool sizes vary Atlantic herring – 4580 m 3Atlantic herring – 4580 m 3 Pacific herring – 15 miles long!Pacific herring – 15 miles long! Positioning in school may involvePositioning in school may involve VisionVision Other senses (mechanical vibrations, olfaction, hearing)Other senses (mechanical vibrations, olfaction, hearing) 1.Types a.Mobile schools Usually consist of single species, size rangeUsually consist of single species, size range b.Stationary schools May contain multiple species, sizesMay contain multiple species, sizes 2.Functions a.Protection against predators b.Increased swimming efficiency c.Beneficial when feeding d.Beneficial when mating

Fig SwimmingFeedingPredator Avoidance

II.Fishes - Behavior B.Migration Generally related to feeding and/or reproductionGenerally related to feeding and/or reproduction DielDiel HorizontalHorizontal VerticalVertical Large ScaleLarge Scale Ex – Skipjack tuna feed in Eastern Pacific, spawn in Western and Central PacificEx – Skipjack tuna feed in Eastern Pacific, spawn in Western and Central Pacific

Fig. 8.22