Lecture 6: Teleost Fishes pt 1

What is the classification of teleosts?

Osteichthyes → Actinopterygii → Neopterygii → Teleostei

What locomotor adaptation characterizes teleosts?

Multiple evolved traits facilitate maneuverable locomotion

How many bones form the teleost operculum?

Four bones

What characterizes teleost vertebrae?

Ossified but lightweight

What type of tail do teleosts have?

Homocercal tail

What supports the teleost tail?

Uroneurals, hypurals, and epurals

What scale types are mentioned for teleosts?

Cycloid and ctenoid scales

What is the swimbladder's main function?

Hydrostatic organ that provides buoyancy

What characterizes teleost fins?

Highly maneuverable; contain rays and spines

Which teleost jaw bones are movable?

Premaxilla and maxilla

What changed about the premaxilla in teleosts?

Increased prominence and functional role

What did jaw-bone dissociation allow?

More mobile feeding systems and greater dietary specialization

What are the four major teleost groups covered?

Elopomorpha, Osteoglossomorpha, Otocephala, Euteleostei

What larval form characterizes Elopomorpha?

Leptocephalus larvae

What do leptocephalus larvae look like?

Very thin and leaflike

How long can leptocephalus larvae last?

Up to 2–3 years

How many branchiostegal rays do elopomorphs have?

Approximately 10–35; more than higher teleosts

What scales are noted in the Elopomorpha lecture notes?

Heavy bony scales containing ganoine

What body plan occurs in many elopomorphs?

Elongate, snake-like body plan

Elopomorpha: Elopiformes — classification and examples?

2 families, 9 species; ladyfishes and tarpons

What distinctive bone do Elopiformes have?

Gular bone under the throat

How many branchiostegal rays do Elopiformes have?

23–35

What is distinctive about the Elopiformes maxilla?

Maxilla is included in the gape

Elopomorpha: Albuliformes — classification and examples?

1 family, 13 species; bonefishes

What is the habitat and significance of bonefishes?

Mostly marine, tropical; popular gamefish

Elopomorpha: Notacanthiformes — classification and examples?

2 families, 28 species; halosaurs and spiny eels

What characterizes Notacanthiformes habitat and tail?

Marine, deep-sea; elongate, tapered tail

Elopomorpha: Anguilliformes — classification and examples?

16 families, approximately 1,000 species; true eels

What pelvic feature characterizes true eels?

Loss of pelvic girdle and pelvic fins

How are true eel median fins arranged?

Dorsal and anal fins are confluent with caudal fin

What happens to scales in Anguilliformes?

Scales are often absent

What does Osteoglossomorpha mean in these notes?

Bony tongues

What is distinctive about the osteoglossomorph tongue?

Well-developed teeth on the tongue, part of the anterior hyoid complex

What scales and habitat characterize Osteoglossomorpha?

Many have huge scales; freshwater, usually tropical

Osteoglossomorpha: Hiodontiformes — classification?

1 family, 2 species; mooneyes

Where do mooneyes live?

Rivers in North America

What pelvic-fin traits distinguish mooneyes?

Distinct pelvic fins with 7 rays

What additional structure do mooneyes have?

Axillary process

Osteoglossiformes — classification?

5 families, more than 250 species

Which groups belong to Osteoglossiformes?

Freshwater butterflyfish, bonytongues, featherfin knifefishes, African aba, African elephantfishes

Which family contains most Osteoglossiformes species?

Mormyridae, with more than 200 species

What is remarkable about Mormyridae brains?

Largest brain-to-body-weight ratio in fishes

What electrical abilities do elephantfishes have?

Generate and receive electrical signals

How does electrical discharge vary in Mormyridae?

Electric organ discharge varies among species and has been used to describe new species

What is the next major teleost cohort?

Otocephala

Otocephala: Clupeomorpha → Clupeiformes — classification?

7 families, more than 400 species

Which fishes belong to Clupeiformes?

Herring, shad, anchovy, sardines

What characterizes Clupeiformes appearance and habitat?

Silvery bodies; mostly marine, some freshwater

What do most Clupeiformes eat?

Plankton; mostly planktivorous

What is an otophysic swimbladder?

Swimbladder that contacts the inner ear

What does the otophysic swimbladder improve?

Sensitivity to low-frequency sounds

Otocephala: Alepocephali → Alepocephaliformes — classification?

2 families, approximately 140 species

Which fishes belong to Alepocephaliformes?

Tubeshoulders and slickheads

What habitat and swimbladder trait characterize Alepocephaliformes?

Marine, deep sea; lack swimbladder

What unusual feature does Platytroctidae have?

Tubes behind head that secrete luminous fluid

How many species does Ostariophysi contain?

More than 7,000 species

What is Schreckstoff?

Fright substance; chemical alarm

What is the Weberian apparatus?

Series of bones connecting swimbladder to inner ear

What does the Weberian apparatus improve?

Low-frequency hearing

What proportion of freshwater fishes are Ostariophysans?

Approximately 64%

Ostariophysi: Anotophysi → Gonorynchiformes — classification?

3 families, approximately 35 species

Which fishes belong to Gonorynchiformes?

Milkfish and relatives

What Weberian trait distinguishes Gonorynchiformes?

Lack a true Weberian apparatus

Ostariophysi: Otophysi → Cypriniformes — classification?

23 families, approximately 4,500 species

Which familiar fishes belong to Cypriniformes?

Minnows, shiners, carp, barbs, dace, goldfish, koi, zebrafish, and many others

What is the largest fish family noted in the lecture?

Cyprinidae: carps and minnows

How many species are in Cyprinidae?

Approximately 1,700 species

What body size characterizes many Cyprinidae?

Mostly small-bodied species

What evolutionary novelty first appears in Cypriniformes?

Pharyngeal jaws

Ostariophysi: Otophysi → Characiformes — classification?

24 families, approximately 2,500 species

Which fishes belong to Characiformes?

Tetras, piranhas, pacus, characins, and many others

What traits are associated with Characiformes?

Adipose fin; many have sharp teeth; ctenoid scales

Ostariophysi: Otophysi → Siluriformes — classification?

39 families, more than 4,000 species

Which fishes belong to Siluriformes?

Catfishes

What fin traits characterize catfishes?

Spine-like dorsal and pectoral rays; adipose fin

What body-covering traits characterize catfishes?

No scales, but may have bony plates

What sensory structures are common in catfishes?

Barbels

Ostariophysi: Otophysi → Gymnotiformes — classification?

5 families, more than 250 species

Which fishes belong to Gymnotiformes?

South American knifefishes, including the electric eel

How are Gymnotiformes described evolutionarily?

Most derived Ostariophysans

What electrical abilities do Gymnotiformes have?

Produce and receive electrical signals

What body and fin plan characterizes Gymnotiformes?

Elongate body; long anal fin; many lack caudal and dorsal fins

What are Euteleostei?

True teleosts; fishes more modern than ostariophysans

What unifies Euteleostei?

Few obvious shared traits, but genetic evidence supports the clade

What is Lepidogalaxiformes' classification?

1 family, 1 species; salamanderfish

What is unusual about Lepidogalaxiformes?

Monotypic order; sister to all other euteleosts

How does the salamanderfish survive drying water?

Buries itself as the water dries

What unusual movement can the salamanderfish perform?

It can turn its head

What is Protacanthopterygii?

Paraphyletic collection of early-diverging true teleosts

Protacanthopterygii: Salmoniformes — classification?

1 family, more than 200 species

Which fishes belong to Salmoniformes?

Salmon, trout, grayling

What habitats do Salmoniformes occupy?

Freshwater, marine, and estuarine

What migratory behavior occurs in many salmonids?

Many are anadromous; some make extensive oceanic migrations

Why are Salmoniformes important?

Ecologically and commercially important

What fin traits characterize Salmoniformes?

Adipose fin; no spines

Protacanthopterygii: Esociformes — classification?

2 families, 14 species

Which fishes belong to Esociformes?

Pikes and pickerels

What habitat and hunting strategy characterize Esociformes?

Freshwater, temperate; ambush predators

Where are Esociformes median fins positioned?

Far back on the body

Protacanthopterygii: Argentiniformes — classification?

4 families, approximately 90 species