WFC 120 after midterm

Teleosts

• Jaws + bones + fin rays

• Typically less bone mass

• Thinner, more flexible scales

• More lightweight

• More advanced jaw mobility

• Moveable premaxilla

• Homocercal tail

Teleost most ancient superorder

Osteoglossomorpha
Elopomorpha

Teleost Jaw

Flexible premaxilla & maxilla

Osteoglossomorpha: Main characteristics

Relatively ‘primitive’ features

Freshwater fishes

Bony tongues with teeth

bonytongues

Matching set of teeth on roof of mouth

• Shear and shred prey
  
  

Arapaima tongues

• used to grind cassava into flour

• Medicinal properties

Osteoglossomorpha - Elephantfish

• Electrolocation

• Generate weak electric field

• Electroreception

• Large brain to body ratio

• Native to Africa (West/Central)

• Benthic (bottom-dwelling)

Osteoglossomorpha - Arapaima

• Very big!

• Up to 10 feet long

• One of largest freshwater fish

• Air-breathing (obligate)

• Highly vascularized swim bladder

• Surface predators

• Fish, birds, mammals

• Mouthbrooders

• Males incubate eggs in mouth

• Native to South America

• Have been introduced

• Thailand + Malaysia

• Considered invasive in some cases

• Bolivia; India

Osteoglossomorpha - Arowanas

• Surface predators

• Fish, insects, shrimp

• Birds (jump up to 6 ft in air)

• Air-breathing (facultative)

• Highly vascularized swim bladder

• Mouthbrooders

• Males incubate eggs in mouth

Elopomorpha

• Mostly marine

• Flat, transparent larvae

• Called Leptocephalus larvae

• Unique to Elopomorphs

Elopomorpha - Eels

• Leptocephalus larvae

• Anguilliform body shape

• Swim bladder

• Usually predatory

• Mostly nocturnal

• Popular food item for humans

American & European Eel catadromous life cycle

• Silver eels mature

• Physiology shifts to saltwater

• Digestive tract degenerates

• Return to ocean 5-25 years

• Semelparous

• spawn once in their lifetime

Elopomorpha - Tarpons

Mostly found in Atlantic Ocean

• Air-breathing

• Vascular swim bladder

Tarpons are a major sport fish

• known for leaping out of water

when hooked on a line

• Up to 8 feet

• Move between salt/freshwater

How do non-native fishes get introduced

Often on purpose

• Fish stocking by govt. agencies

• Illegal introductions

Sometimes on accident

Fish stocking by govt. agencies

• improve fishing/recreation

• Biological control (i.e. mosquitofish)

Mule packing/plane dropping

Sometimes on accident - fishes get introduced

• Boats/vessels carry organisms

• Changing waterway connections

• Pet/aquarium trade

• Live bait release

Potential negative impacts of non-native species introductions

Degradation of habitat required by native species

Increased competition with native species

Increased predation of native species

Hybridization between non-native + native species

Introduction of novel disease/parasites

Degradation of habitat required by native species

ex) Carp uproot plants, increase turbidity, contribute to HABs

Hybridization between non-native + native species

Issues with ‘purity’ for legal purposes

Can lead to maladaptive genotypes

Hybrid individuals can be sterile

are non-native species introductions always bad

Not necessarily!

• Many introduced species:

• Don’t survive in novel environment

• Most introduced species don’t become ‘invasive’

• Especially in our ultra-modified ecosystems, introduced species can become “naturalized” (i.e. integrated into biotic community)

• can fill an empty ecological niche, provide food for native fishes, or provide biological control

Salmoniformes

• Very popular game fish

• Adipose fin present

• All spawn in freshwater

• Many anadromous

• Single row of sharp teeth

Salmoniformes - Native in California

• Salmon

  • Chinook

  • Coho

• Trout

  • Rainbow

  • Costal Cutthroat

Salmoniformes - Native trout

Steelhead - anadromous

Coastal cutthroat trout - anadromous

Rainbow trout

McCloud River Redband Trout

Lahontan cutthroat trout

Paiute cutthroat trout

CA golden trout

Salmoniformes - Non-native trout

Brook trout

Brown trout

Native salmonids in California

Chinook salmon

Coho salmon

Rainbow trout

Coastal cutthroat trout

Salmon are anadromous

• Anadromous = born in freshwater, migrate to ocean, migrate upstream to spawn in freshwater

• Timing + duration of each stage varies across species

• Usually spend more time in ocean than freshwater

  • Critical life stages (spawning + rearing) occur in freshwater

• Turn red during spawning

  • Many species

  • males usually brighter red

Why might it be advantageous for salmon to keep their silvery color until they begin their spawning migration?
A) Silvery color attracts a mate
B) Silvery color provides camouflage during pelagic marine phase
C) Silvery color catches the light and draws attention from other species
D) Silvery color mimics other fish that are poisonous

B) Silvery color provides camouflage during pelagic marine phase

Chinook salmon

Largest salmon in Pacific

• Juveniles eat insects, plankton, small crustaceans

• Adults are piscivorous (mostly eat forage fish)