Habitat Diversity/Extreme Habitats

Describe the migratory ranges of large marine predators

they tend to have ocean-basic sized migratory ranges, and often avoid the areas of other large predators

How does regional endothermy affect migratory trends?

These fish tend to have greater migration ranges.

What cues do fish use to navigate?

• olfactory cues

• sun compas

• geomagnetic landmarks

• geomagnetic compass

Olfactory cues

• juvenile salmon imprint on chemical substances in the streams they are born in

Sun compass

• limited evidence

• maybe marlin, parrotfish, salmon

Geomagnetic landmarks

• geological features with magnetic signatures

• some evidence in elasmobranchs

Geomagnetic compass

• using earths magnetic field to navigate

• some evidence in elasmobranchs, true eels, salmon, tuna

Vertical migration

• involved billions and billions of inverts and fishes

• triggered by light levels

• upward migration at dusk to feed, downward migration at dawn

• occurs in both freshwater and marine habitats

Pelagic

• open ocean (lacks structure)

Benthic

• sea floor (structures habitats)

Littoral zone

• nearshore habitats, light reaches bottom

Neritic zone

• on the continental shelf, offshore of the littoral

Oceanic zone

• offshore habitats beyond continental shelf

Photic zone

• depths with light from the surface

Aphotic zone

• depths with no surface light

Epipelagic (Euphotic zone)

• 0-200m

• high solar insolation (sun exposure)

• primary production > respiration

Epipelagic fish features

• fusiform with forked tails

• small fishes tend to school

• large fishes tend to be migratory

• silvery color and countershading

Epipelagic representative fishes

• halfbeaks

• needlefishes

• some tunas

Mesopelagic (twilight zone)

• 200-1000m

• some downwelling light

• respiration > photosynthesis

• production comes from the surface

Mesopelagic fish features

• bioluminescence

• small size

• large eyes

• vertical migration

Mesopelagic representative features

• bristlemouths

• lanternfishes

Bathyal and Abyssal plains

benthic

• vast expanses of deep sea

• little structure, mud/ooze

• no in situ production

Bathyal and Abyssal fish features

• tapered tails

• bioluminescence less common

• many transient scavenders

• many demersal species (occasional benthic association)

Bathyal and Abyssal representative fishes

• grenadier, deep sea skates, tripodfishes, snailfishes

Hydrothermal vents

Benthic

• associated with hotspots/volcanic activity

• often with tube worms providing structure

• not very diverse

Hydrothermal vent representative fish

• eelpouts, cusk-eels, one flatfish

Intertidal zone

bethic

• area between high and low tides

• highly variable

• high wave action and turbulence

Intertidal fish features

• small

• cyptic

• adaptations for station holding

Intertidal representative fish

• sculpins, clingfishes, pricklebacks

Coral Reefs

benthic

• highly structured environments composed of coral skeletons

• harbor tons of biodiversity

• common in shallow tropical regions

coral reef fish features

• high morphological diverisity

• many laterally compressed forms

• many benthic biting species

coral reef representative fishes

• butterfly fishes, surgeonfishes, angelfishes, wrasses

Kelp forests

demersal

• kelp (algae) provides vertical structure above benthic substrates

• support diverse fish communities

• vulnerable to environmental change and predation

• often found in areas of coastal upwelling

Estuaries

• partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it

• important nursery grounds for fishes

• species with wide tolerance to variation in environmental conditions

Mangroves

• coastal habitats formed by trees/shrubs that are tolerant to salt

• can be brackish to hypersaline

• important nursery grounds for fishes

Freshwater habitats

• 0.01% of available water on earth

• home to nearly 50 percent of all fish species

• generally shallow (compared to the ocean)

Why are freshwater fishes so diverse?

1. freshwater habitats are generally more productive than marine environments

2. Freshwater habitats are isolated more frequently

Primary freshwater fishes

• strictly confined to freshwater

• no saltwater tolerance

• long evolution history in freshwater

• ex. tetras

Secondary freshwater fishes

• mostly restricted to freshwater

• occasionally tolerate saltwater

• groups is occasionally marine in origin

• ex. gobies

Freshwater representatives of marine groups

• freshwater pufferfish

• herring

Occasional visitors to freshwater

• diadromous fishes (ex. salmon)

• euryhaline species (ex. bull shark)

Rivers and streams

• huge variety in size and flos

  • highly variable over time

  • can be highly fragmented habitats

river and stream fish features

• streamlined and elongate

• tiny species are benthic, resist currents

• larger species swim in currents

Lakes

• still water (lentic)

• huge variety in size and depth

• like aquatic islands

• new lakes habitats have potential to stimulate rapid diversification

lake fish features

• deep-bodied

• morphological differences between benthic mid-water species

African Great lakes

• lakes tanganyika, malawi, and victoria

• 10 million years to 100,000 years old

• cichlid adaptive radiations

  • hundreds of species

  • high morphological and ecological diversity

Adaptive radiation

• diversification from a single species

• response to ecological opportunity

Lake Baikal, Russia

• oldest lake (over 25 million years old)

• deepest lake (1,642 m deep)

• deepest living freshwater fish (>1000 m)

• home to an adaptive radiation of sculpins

Swamps and Wetlands

• flooded ecosystems

• can be short lived or permanent

• variable O2 and pH

• lots of organic input

• fish communities similar to lakes

Caves

• dark habitats

• few predators

• often stagnant or slow moving water

• low productivity

Caves fish features

• blind (eye loss)

• depigmented

Sediments

• some fishes are fossorial and can burrow deep under sediments

• for refuge or to escape desiccation

• most tolerate O2 conditions

• tends to be elongate

• Ex. salamenderfish, tarumania walkerae

High flow habitats - fish traits

• streamlined body shapes

  • benthic fishes are often flat

• adaptations for station holding

  • large grippy pectoral fins

  • modified pectoral-fin spines

  • suction organs

Dorsal Adhesive Discs

• only found in remoras (shark suckers)

• made from a modified dorsal fin

• used to hitchhike around the ocean on marine megafauna

Oral Adhesive Discs

• mainly found in catfishes, gobies, and lampreys

• made from modified mouthparts and a fleshy lip

• used to attach to sharks (lampreys) and climb waterfalls (gobies)

Ventral Adhesive Discs

• found in clingfish, gobies, snailfish, and lumpfish

• made from modified pelvic fins or pectoral and pelvic fins

• primarily used for stations holding but some gobies climb waterfalls

Clingfish adhesion

• adheres well on smooth and rough surfaces

• dead fish can generate attachment forces 300x its body weight

How does clingfish adhesion work?

• internal bones make the disc stiff

• a soft rim deforems to create the seal for suction

• small surface pads increase friction and resist slip

Terrestrial habitats

used by fish for

• loss of habitat

• escape from predators

• new food sources

• find mates

Representative amphibious fishes

• muskippers, blennies, bichir

Undulatory Tripod Gait

Terrestrial locomotion

• generate propulsion by bending the body and pushing

• minimal use of the paired fins

• requires little to no morphological adaptation

• used by most amphibious fishes

Jumping

Terrestrial locomotion

• push off the ground with the tail

• no use of the paired fins

• no conformed morphological changes needed to jump

• commonly used by blennies, mudskippers, and mangrove rivulus

Walking gait

Terrestrial locomotion

• use pectoral and pelvic fins like limbs

• coordinate fins to walk like salamanders

• required podifications of the pectoral and pelvic girdles

• behavior used by Cryptotora and epaulette sharks

Crutching gait

Terrestrial locomotion

• use pectoral fins like crutched to propel body forward

• requires substantial modifications of the pectoral girdles

• behavior used only by mudskippers

Deep Sea Feeding tools

• bioluminescence

• large jaws and extendable stomachs

• large fangs

Bioluminescence

• Lures are used to attract prey

  • anglerfish emit light with symbiotic bacteria while some dragonfish produce their own light with photophores

• ‘night vision goggles’ to find prey

Large jaws and extendable stomachs

• help capture any potential prey

• dragonfishes have lost vertebrae behind the skull to rotate head more and open jaws wider

Large Fangs

• also used to capture potential prey

• fangs this large are rare in shallower waters

• present in many lineages of mesopelagic fishes