1. Sensory Systems, Behavior, Reproduction Biology of Fishes 11.1.12

2. Presentations & Other Assignments Presentations & Other Assignments Presentation Guidelines – online Friday Presentation Guidelines – online Friday Guest Lecture II – Fishes of the Great Lakes 11.8.2012 Guest Lecture II – Fishes of the Great Lakes 11.8.2012 Syllabus Revisions Syllabus Revisions Exam II – November 20 Exam II – November 20 Upcoming Topics Upcoming Topics Sensory Systems Sensory Systems Behavior Behavior Reproduction Reproduction Overview

3. What fishes use to gather information about their environment What fishes use to gather information about their environment Accurate and up-to-date information about surrounding conditions Accurate and up-to-date information about surrounding conditions Critical to decision-making success in feeding, predator-avoidance, mate selection Critical to decision-making success in feeding, predator-avoidance, mate selection Sensory Systems

4. Mechanoreception Mechanoreception Involves detection of movement Involves detection of movement 2 major systems 2 major systems Lateral line Lateral line Inner ear Inner ear Collectively referred to as the “acoustico-lateralis” system Collectively referred to as the “acoustico-lateralis” system Sensory Systems

5. Lateral line Lateral line Unique sense organ found in all fishes (except hagfish) and some amphibians Unique sense organ found in all fishes (except hagfish) and some amphibians Adapted for life in aquatic environments Adapted for life in aquatic environments Sensory system stimulated mechanically by motion Sensory system stimulated mechanically by motion weak water currents hitting the body result in distinct fin movements weak water currents hitting the body result in distinct fin movements Local cauterization of lateral line results in no fin movements Local cauterization of lateral line results in no fin movements Sensory Systems

6. Lateral line – Structure Lateral line – Structure Basic unit that senses motion is the neuromast Basic unit that senses motion is the neuromast Neuromast consists of cupula – jelly-like substance and sensory hair cells Neuromast consists of cupula – jelly-like substance and sensory hair cells Sensory Systems

7. Lateral line – Structure Lateral line – Structure Basic unit that sense motion is the neuromast Basic unit that sense motion is the neuromast Sensory Systems

8. Lateral line – Structure Lateral line – Structure Basic unit that senses motion is the neuromast Basic unit that senses motion is the neuromast Sensory Systems

9. Lateral line – Structure Lateral line – Structure 2 types of neuromast 2 types of neuromast Superficial neuromast Superficial neuromast Located on surface, distributed on head and body Located on surface, distributed on head and body Tend to be smaller and have fewer hair cells Tend to be smaller and have fewer hair cells Canal neuromasts Canal neuromasts Located in canals in head and along body (lateral line) Located in canals in head and along body (lateral line) Tend to be larger and have more hair cells Tend to be larger and have more hair cells Sensory Systems

10. Lateral line – Structure Lateral line – Structure Superficial neuromast Superficial neuromast Canal neuromasts Canal neuromasts Sensory Systems

11. Lateral line – function Lateral line – function Identify and locate stationary object Identify and locate stationary object Prey detection – (e.g. sculpin-zooplankton, pike-fishes, terrestrial insects) Prey detection – (e.g. sculpin-zooplankton, pike-fishes, terrestrial insects) Detect flow differences (maintaining position, prey detection – candiru catfish) Detect flow differences (maintaining position, prey detection – candiru catfish) Communicate for spawning synchronization Communicate for spawning synchronization Synchronized swimming – schools (even blind fishes can school) Synchronized swimming – schools (even blind fishes can school) Sensory Systems blind cave fish

12. Inner Ear Inner Ear Also used for mechanoreception Also used for mechanoreception Provides information on the orientation and movement of a fish Provides information on the orientation and movement of a fish Critical for maintaining balance and position Critical for maintaining balance and position Sensory Systems

13. Inner Ear – structure Inner Ear – structure Semicircular canals Semicircular canals Filled with fluid (endolymph) Filled with fluid (endolymph) Movement of the fish causes movement of fluid in semicircular canals Movement of the fish causes movement of fluid in semicircular canals Enlarged area (ampulla) contains sensory hair cells that are displaced by movement of fluid Enlarged area (ampulla) contains sensory hair cells that are displaced by movement of fluid Movement of hair cells results in changes response of sensory neurons – provides brain with information on changes in acceleration and orientation Movement of hair cells results in changes response of sensory neurons – provides brain with information on changes in acceleration and orientation Sensory Systems

14. Inner Ear – structure Inner Ear – structure Sensory Systems

15. Inner Ear – structure Inner Ear – structure Otoliths Otoliths Ear “bones” or “stones” actually crystalline formation Ear “bones” or “stones” actually crystalline formation Provide information on orientation and movement Provide information on orientation and movement Can be used in aging fishes Can be used in aging fishes Sensory Systems

16. Inner Ear – structure Inner Ear – structure Otoliths Otoliths Sensory Systems

17. Hearing Hearing Inner ear also responsible for hearing Inner ear also responsible for hearing Most fish tissue transparent to sound – density of tissue is similar to water Most fish tissue transparent to sound – density of tissue is similar to water Sound vibrations travel right through the fish Sound vibrations travel right through the fish Otoliths denser – vibrate for sound detection Otoliths denser – vibrate for sound detection Otolith vibration sets hair cells in motion – changes response of neurons Otolith vibration sets hair cells in motion – changes response of neurons Sensory Systems

18. Hearing – Gas Bladder Hearing – Gas Bladder Also increases sensitivity to sound Also increases sensitivity to sound Sound waves cause vibrations in gas bladder – transmitted to inner ear Sound waves cause vibrations in gas bladder – transmitted to inner ear Weberian apparatus (Otophysi) Weberian apparatus (Otophysi) Clupeomorpha have extensions of gas bladder that lie next to inner ear Clupeomorpha have extensions of gas bladder that lie next to inner ear Other fishes – gas bladder lies close enough to increase sensitivity Other fishes – gas bladder lies close enough to increase sensitivity Sensory Systems

19. Sum of all motor responses to all internal and external stimuli Sum of all motor responses to all internal and external stimuli Fishes exhibit a host of behaviors associated with feeding, predator-avoidance, reproduction, locomotion, interactions Fishes exhibit a host of behaviors associated with feeding, predator-avoidance, reproduction, locomotion, interactions Behaviors are plastic – vary with life stage, season, time of day, environment, perceived risks; also individuals, populations Behaviors are plastic – vary with life stage, season, time of day, environment, perceived risks; also individuals, populations Behavior

20. Dynamic displays – involve posturing Dynamic displays – involve posturing Ways of communicating to one another – courtship, territory defense, dominance, signaling to young Ways of communicating to one another – courtship, territory defense, dominance, signaling to young Include visual displays – rapid change in color, exposure of colored structures, mouth/gill flaring, fin flicking, raising fins Include visual displays – rapid change in color, exposure of colored structures, mouth/gill flaring, fin flicking, raising fins Behavior

21. Dynamic displays – involve posturing Dynamic displays – involve posturing Lateral displays (cichlids, anemone fishes) Lateral displays (cichlids, anemone fishes) Frontal displays (kissing gouramis, some cichlids) Frontal displays (kissing gouramis, some cichlids) Communication via sound, chemicals (alarm substance), touch, electricity Communication via sound, chemicals (alarm substance), touch, electricity Behavior

22. Parental Care – association between parent and offspring after fertilization that enhances survivorship Parental Care – association between parent and offspring after fertilization that enhances survivorship Increases survival by reducing predation risk, increasing food access Increases survival by reducing predation risk, increasing food access Many fishes provide no parental care – egg dispersers, pelagic eggs Many fishes provide no parental care – egg dispersers, pelagic eggs Some parental care is common among fishes Some parental care is common among fishes Behavior TaxonMale careFemale careBoth parentsNo care Mammals090100 Birds28900 Non teleosts666028 Teleosts117478 % of families showing parental care

23. Unlike other vertebrates, males are most common care-giver in fishes Unlike other vertebrates, males are most common care-giver in fishes Females invest +energy in egg production; guarding would reduce amount of future reproduction Females invest +energy in egg production; guarding would reduce amount of future reproduction Paternity assurance – makes sure only one is fertilizing eggs Paternity assurance – makes sure only one is fertilizing eggs Tradeoff – costs energy and reduces fecundity Tradeoff – costs energy and reduces fecundity Behavior TaxonMale careFemale careBoth parentsNo care Mammals090100 Birds28900 Non teleosts666028 Teleosts117478 % of families showing parental care

24. Two types – behavioral or physiological Two types – behavioral or physiological Substrate guarding Substrate guarding Most common Most common Male constructs nest; guards, fans, cleans eggs – may also guard young (catfishes, minnows, sculpin, stickleback, bowfin, SA lungfish) Male constructs nest; guards, fans, cleans eggs – may also guard young (catfishes, minnows, sculpin, stickleback, bowfin, SA lungfish) Mouth brooding Mouth brooding Eggs and sometimes young carried in mouth (lumpfishes, gouramis, arowanas, cichlids Eggs and sometimes young carried in mouth (lumpfishes, gouramis, arowanas, cichlids External egg-carrying External egg-carrying Eggs carried on lower lip, on head, or own belly (several catfishes) Eggs carried on lower lip, on head, or own belly (several catfishes) Brood pouch Brood pouch Carried inside pouch of male – seahorses and pipefishes Carried inside pouch of male – seahorses and pipefishes Behavior - Parental Care

26. The most obvious form of social behavior in fishes is the formation of groups The most obvious form of social behavior in fishes is the formation of groups Shoals – unorganized grouping of fishes Shoals – unorganized grouping of fishes Similar to a flock of birds Similar to a flock of birds May gather together to feed, breed, or seek refuge (salmon, gars, minnows) May gather together to feed, breed, or seek refuge (salmon, gars, minnows) Basically “milling around”, no organized or coordinated swimming Basically “milling around”, no organized or coordinated swimming Schools – synchronized swimming groups – exhibit coordinated behaviors Schools – synchronized swimming groups – exhibit coordinated behaviors One of the behaviors exhibited by fish in shoals One of the behaviors exhibited by fish in shoals In N. American literature “school is used to cover both shoaling (unorganized) and schooling (organized) In N. American literature “school is used to cover both shoaling (unorganized) and schooling (organized) Behavior

27. Schools – Why do they form? Schools – Why do they form? Fish act as individuals – don’t school for the benefit of the group Fish act as individuals – don’t school for the benefit of the group “selfish” – ensure access to food, minimize predation “selfish” – ensure access to food, minimize predation Hydrodynamic advantage – save energy by drafting – many studies, but little solid evidence that fish save energy by schooling Hydrodynamic advantage – save energy by drafting – many studies, but little solid evidence that fish save energy by schooling Most likely relate to foraging and predator avoidance Most likely relate to foraging and predator avoidance Foraging Foraging Find food faster Find food faster Prey capture may be easier Prey capture may be easier Hunting in packs (tuna, sailfish) Hunting in packs (tuna, sailfish) Tradeoff – must compete with individuals of group Tradeoff – must compete with individuals of group Behavior

28. Schools – Why do they form? Schools – Why do they form? Anti-predator strategy – the need to avoid predation is a major selective force that shapes schooling behavior (takes precedence over finding a meal) Anti-predator strategy – the need to avoid predation is a major selective force that shapes schooling behavior (takes precedence over finding a meal) Evasion – attack success of predators declines with group size; most likely due to confusion of predator Evasion – attack success of predators declines with group size; most likely due to confusion of predator Compaction – in presence of predator, group becomes more compact and cohesive Compaction – in presence of predator, group becomes more compact and cohesive Detection – many eyes aid in predator detection Detection – many eyes aid in predator detection Skittering – minnows detect predator and leap out of water then return to school – may alert others in school, triggering anti-predator behavior Skittering – minnows detect predator and leap out of water then return to school – may alert others in school, triggering anti-predator behavior Predator inspection – fishes (usually small groups) approach predator Predator inspection – fishes (usually small groups) approach predator Behavior

29. Schools – Why do they form? Schools – Why do they form? Reproduction Reproduction Increases likelihood of finding a mate Increases likelihood of finding a mate Coordinates readiness (maturity) through hormonal & behavioral cues Coordinates readiness (maturity) through hormonal & behavioral cues Facilitates arrival at spawning site at correct time (fish migrations – salmon, whitefish, mullet) Facilitates arrival at spawning site at correct time (fish migrations – salmon, whitefish, mullet) Behavior

30. Fishes – most diverse group of vertebrates – incredibly diverse reproductive strategies/mechanisms Fishes – most diverse group of vertebrates – incredibly diverse reproductive strategies/mechanisms Reproductive strategies are adaptations to maximize the fitness of individuals – ensure genes are passed on Reproductive strategies are adaptations to maximize the fitness of individuals – ensure genes are passed on Overview of fish mating systems Overview of fish mating systems Reproduction

31. Frequency of spawning Frequency of spawning Iteroparity (iteroparous) Iteroparity (iteroparous) More than one spawning during a lifetime More than one spawning during a lifetime Most fishes use this strategy Most fishes use this strategy K-selected species – grow slowly, reproduce late, produce fewer young, longer life expectancy, lower reproductive effort (spread across time), may provide parental care K-selected species – grow slowly, reproduce late, produce fewer young, longer life expectancy, lower reproductive effort (spread across time), may provide parental care Stable, predictable habitats – survival to following year is high Stable, predictable habitats – survival to following year is high Lower fecundity, but spread out to ensure some reproduction Lower fecundity, but spread out to ensure some reproduction ~25-60% of somatic energy used for reproduction ~25-60% of somatic energy used for reproduction Reproduction

32. Frequency of spawning Frequency of spawning Semelparity (semelparous) Semelparity (semelparous) Spawn once and die Spawn once and die Diadromous or highly migratory fishes tend to be semelparous (salmon, lamprey, anguillid eels) Diadromous or highly migratory fishes tend to be semelparous (salmon, lamprey, anguillid eels) R-selected species – grow fast, reproduce early, produce many young, shorter life expectancy, high reproductive effort (“big bang”), no parental care R-selected species – grow fast, reproduce early, produce many young, shorter life expectancy, high reproductive effort (“big bang”), no parental care Unstable/unpredictable environments – high mortality Unstable/unpredictable environments – high mortality Place eggs and young in ideal growing conditions Place eggs and young in ideal growing conditions Overwhelm predators Overwhelm predators ~60-85% somatic energy used for reproduction ~60-85% somatic energy used for reproduction Reproduction

33. Modes of spawning Modes of spawning Oviparous – fish lay eggs that are fertilized externally, mother provides no nutrition other than yolk (most fishes) Oviparous – fish lay eggs that are fertilized externally, mother provides no nutrition other than yolk (most fishes) Ovoviviparous – eggs are retained in female and fertilized internally, mother provides no nutrition (most sharks, coelacanth, some poeciliids) Ovoviviparous – eggs are retained in female and fertilized internally, mother provides no nutrition (most sharks, coelacanth, some poeciliids) Viviparous – eggs retained in female, fertilized internally, mother provides nutrition (some sharks, goodeids, poeciliids) Viviparous – eggs retained in female, fertilized internally, mother provides nutrition (some sharks, goodeids, poeciliids) Reproduction

34. Types of fertilization Types of fertilization External External Most fishes Most fishes Less time and energy spent in courtship Less time and energy spent in courtship Increase number of potential mates Increase number of potential mates higher fecundity – more offspring produced higher fecundity – more offspring produced Internal Internal Few groups of fishes Few groups of fishes Chondrichthyes, guppies, mollies Chondrichthyes, guppies, mollies Requires lengthy courtship Requires lengthy courtship Intromittent organ – transfer sperm to females (claspers, modified anal fin) Intromittent organ – transfer sperm to females (claspers, modified anal fin) Reproduction

35. Mating Systems Mating Systems Promiscuous – no obvious mate choice – both spawn with multiple partners Promiscuous – no obvious mate choice – both spawn with multiple partners Polygamy – only one sex has multiple partners Polygamy – only one sex has multiple partners Polyandry – one female, several males Polyandry – one female, several males Relatively uncommon Relatively uncommon Anemonefish, anglerfishes, gars Anemonefish, anglerfishes, gars Polygyny – one male, multiple females Polygyny – one male, multiple females Most common Most common Territorial males care for eggs/young – visited by multiple females (sculpins, sunfishes, darters, damselfishes some cichlids); harems may also form Territorial males care for eggs/young – visited by multiple females (sculpins, sunfishes, darters, damselfishes some cichlids); harems may also form Reproduction

36. Mating Systems Mating Systems Monogamy – fish mate exclusively with same individual Monogamy – fish mate exclusively with same individual N.American freshwater catfishes, butterflyfishes, some cichlids, seahorses N.American freshwater catfishes, butterflyfishes, some cichlids, seahorses Reproduction

37. Gender Systems – in most fishes the sex of an individual is determined at early stage and fixed; some fishes are hermaphrodites and can function as males and/or females Gender Systems – in most fishes the sex of an individual is determined at early stage and fixed; some fishes are hermaphrodites and can function as males and/or females Simultaneous – capable of releasing viable eggs and sperm during same spawning Simultaneous – capable of releasing viable eggs and sperm during same spawning Some can self-fertilize (Cyprinodontiform Rivulus); likely adaptation to lower population size, isolated habitats Some can self-fertilize (Cyprinodontiform Rivulus); likely adaptation to lower population size, isolated habitats Alternate sex roles during spawning (Serranus); male with harem of hermaphrodite females – male removed, largest hermaphrodite female changes into male Alternate sex roles during spawning (Serranus); male with harem of hermaphrodite females – male removed, largest hermaphrodite female changes into male Reproduction

38. Gender Systems – some fishes are hermaphrodites and can function as males and/or females Gender Systems – some fishes are hermaphrodites and can function as males and/or females Sequential – function as one sex for part of their life, then switch Sequential – function as one sex for part of their life, then switch Protogynous (protogyny) – start female, change to male; more common Protogynous (protogyny) – start female, change to male; more common Protandrous (protandry) – start male, change to female; less common Protandrous (protandry) – start male, change to female; less common Parthenogenetic – alternative to traditional gender roles Parthenogenetic – alternative to traditional gender roles All female but require sperm from other species to activate cell division in eggs (genetic info from males is not conserved) All female but require sperm from other species to activate cell division in eggs (genetic info from males is not conserved) Produce daughters genetically identical to mother (Poeciliidae in TX and Mexico) Produce daughters genetically identical to mother (Poeciliidae in TX and Mexico) Reproduction