Feeding, social, and symbiotic behaviors

Diet The bigger the fish, the more food resources it can consume the better chance of avoiding predators ‘bigger is better’ ( Houde 1987 ) or ‘you are what you eat’ ( Brillat-Savarin 1826 *) or ‘you are what you CAN eat’ ( Marsden, 2012 ) – mouth configuration – teeth – gape – speed *“ Dis-moi ce que tu manges, je te dirai ce que tu es. ”

piscivores (fish-eating) planktivores (mostly zooplankton) pickers, scrapers, molluscivores - insect larvae, snails, etc. detritivores herbivores (rare) – periphyton, phytoplankton, filamentous algae, macrophytes, fruit Fish food resources

Fish feeding modes Planktivores ( Clupeiformes ) –algae –zooplankton

Fish feeding modes Planktivores ( Clupeiformes ) –algae –zooplankton ‘predators’ - visual prey location ‘strainers’ - use gill rakers to sieve food Basking shark (Cetorhinus maximus)

Fish feeding modes Detritivores ( Cypriniformes, Siluriformes, Acipenseriformes ) benthic feeders sub-terminal mouths

Fish feeding modes Insectivores benthic insect larvae ( Cypriniformes, Scorpaeniformes ) surface feeders on terrestrial insects ( Salmoniformes )

Fish feeding modes Herbivores ( Cypriniformes ) algavores - sieve through gill rakers grazers - eat macrophytes with crushing teeth scrapers - scrape periphyton and filamentous algae

Fish feeding modes Frugivores ( Carachiformes ) Pacu – crushing teeth, eats fruit, seeds, nuts –Important role in seed dispersal

Fish feeding modes Piscivores visual predators sharp teeth on multiple bones types: –sit-and-wait, ‘ambush’ predators (Amiiformes, Esociformes) –pelagic chasers (Salmoniformes)

Fish feeding modes Molluscivores ( Cypriniformes, Acipenseriformes, Perciformes ) grinding pharyngeal teeth

Fish feeding modes “Hematophagy” ( Petromyzontiformes ) - parasites rasp hole in prey, suck out fluids S. Beavais USFWS

Fish feeding modes ram suction biting picking scraping

Gape limitations Angler (Lophius piscatorirus)

Feeding behaviors prey recognition pursuit capture processing

Feeding behaviors Optimal foraging (maximize gain, minimize energetic losses)

Feeding behaviors Optimal foraging (maximize gain, minimize energetic losses)

Feeding behaviors Optimal foraging (maximize gain, minimize energetic losses)

Low prey density prey

Feeding behaviors Optimal foraging (maximize gain, minimize energetic losses) bluegill choose zooplankton sizes based on abundance stream foragers pick optimum location where current is low, visibility of prey high -sub-dominant individuals tend to have less optimal habitats

Feeding behaviors Optimal foraging (maximize gain, minimize energetic losses) bluegill choose zooplankton sizes based on abundance stream foragers pick optimum location where current is low, visibility of prey high -sub-dominant individuals tend to have less optimal habitats prey switching – use of search image?

Social behaviors Dominance hierarchies use displays and nips rather than full-blown aggression - round gobies will flare fins and operculae, and spit sand leaves dominant fish with optimal access to refuge, food, mates usually size-related

Social behaviors Cooperative behaviors schooling to feed, round up prey shoaling to optimize finding food fish follow those that are most successful group feeding dictated by productivity of environment: if low, feeding likely solitary

Predator avoidance behaviors schooling (discussed) leaping from surface - flying fish, mullet, minnows roll-and-flash of minnows - makes fish highly visible, then it disappears Robert Harrington

Interspecific interactions Types of symbiosis species 1species 2 mutualism + + parasitism + - commensalism + 0

Symbioses: mutualism reproduction: species that guard juveniles of other species (mutualism) - keep them outside own flock as protection from predators - if they are predators of the parent species’ competitor larval stream cyprinids most abundant in pools with smallmouth bass, which eat larval predators

Symbioses: mutualism feeding: - cooperative feeding between groupers and morays

Symbioses: commensalism feeding: - remoras and sharks or turtles - cichlid species that ‘guard’ feeding partner

Symbioses Shelter: commensal or mutual

Symbioses Damselfish ‘cultivate’ algal gardens (mutualistic?) conspecifics regarded as competitors and chased away

Symbioses: parasitism Feeding - lamprey….. - cichlids that specialize on scales - juvenile piranhas school w. other species then eat their tail fins - cutlips minnow eats eyes of other fish - pearlfish hide in sea cucumbers - then also eat viscerasea cucumbers

Symbioses: parasitism Feeding - lamprey….. - cichlids that specialize on scales - juvenile piranhas school w. other species then eat their tail fins - cutlips minnow eats eyes of other fish - pearlfish hide in sea cucumbers - then also eat viscera - candiru catfish, sub-nose eel are internal, burrowing parasites

Symbioses: mutualism Cleaning behavior: How: may be substrate pickers - other fishes' bodies as substrate development of cleaner's attractiveness advertising coloration of cleaner ‘tickle’ behavior movement of cleanee to station and stance

Symbioses: mutualism Cleaning behavior What: removal of ectoparasites, scales, mucus, etc. from body surface, oral cavity and/or gill cavity Who: juveniles of many species wrasses (Labridae) (Batesian mimics) Why: benefits of being cleaned predaceous mimics…. (Mullerian mimics)