Bony Fishes

1
Bony Fishes Diversity and Taxonomy

• Clade Osteichthyes fishes exhibiting ossified
  skeletons (bone replaces cartilage during
  development), swim bladders (or lungs), and
  shared cranial and dental features most with
  homocercal tails
• Class Actinopterygii the ray-finned fishes (most
  diverse of vertebrates, 27,000 species)
  earliest forms include paleoniscids (Paleozoic)
• Bichirs possess lungs, heavy ganoid scales
  found in Africa (freshwater)
• Sturgeons and Paddlefishes freshwater and
  anadromous species large bodied source of
  caviar (many species endangered as a result of
  overfishing)
• Gars and Bowfin (early neopterygians) found in
  the Great Lakes and the Mississippi River basin
  gars piscivorous
• Teleosts modern bony fishes (96 of fishes)
  light, flexible scales (cycloid or ctenoid)
  adaptations of fins (rays and spines) and swim
  bladder increased maneuverability adaptations
  of lower jaw suspension allowed rapid jaw
  protrusion (allows suction feeding) extra set
  of jaws (pharyngeal jaws) in some taxa used for
  crushing shells
• Class Sarcopterygii the lobe-finned fishes
• Early Forms all had lungs and gills including
  rhipidistians (freshwater and coastal taxa with
  fleshy fins most diverse in late Paleozoic gave
  rise to early tetrapods)
• Lungfishes six extant species (African and South
  American species able to survive through dry
  seasons in mud beds) functional lungs
• Coelacanths peak diversity in Mesozoic one
  extant genus (Latimeria) discovered off South
  Africa (1938) and Comoro Islands, and then
  Sulawesi, Indonesia (1998) diphycercal tail
  deep sea habitat largest eggs of a fish (9 cm
  diameter)

2
Fig. 24.1
3
Fig. 24.2
4
Fig. 24.18 and 24.19
5
Fig. 24.20
6
Fig. 24.22 and Fig. 24.23
7
Bony Fishes Form and Function

• Calcified bones including operculum (covers
  gills), otoliths (ear bones that control
  balance fish can get sea sick!), and fin rays
  (allow maneuverability)
• Teleosts with fin spines (anti-predation) many
  with modifications of fins (esca of anglerfishes,
  suckers, venomous spines, membranous fins of
  flying fish)
• Swim bladder gas-filled sac for buoyancy
  control some fill via bloodstream (but only
  slowly limited depth ranges), others adjust via
  mouth and must live near surface (ex.
  anchovies) some lack or is vestigial (tunas,
  flatfishes) good target for echolocation
  stores gases and can function as a lung sound
  production (ex. croakers) Weberian ossciles
  increase hearing ability
• Multiple gills gill rakers trap prey gas
  exchange at gill filaments (thin and full of
  blood capillaries) gills accomplish excretion
  along with kidneys
• Flattened, flexible scales (cycloid or ctenoid)
• Locomotion anguilliform (body undulation, ex.
  eels) carangiform and thunniform (trunk
  musculature, ex. jacks, tunas) fin-movements
  (ex. boxfish)
• Body forms Fusiform (torpedo shaped tunas,
  etc.) Laterally compressed (flat- fishes,
  butterflyfishes, etc.) Snake-like (eels)
  Globular (benthic groups) Tubular (ex.
  trunkfish)
• Reproduction sexual dimorphism, sex reversal,
  and hermaphrodites common (ex wrasses,
  groupers) some monogamous (butterflyfishes)
  most with pelagic, planktonic larval stages
  some brood benthic eggs and larvae (ex.
  damselfishes) some with live birth (ex.
  surfperches, seahorses males with pouch)

8
Fig. 29.8
9
Fig. 24.15
10
Fig. 24.27 and Fig. 24.28
11
Fig. 24.29
12
Fig. 31.20
13
Fig. 24.30
14
Fig. 24.16
15
Fig. 24.17
16
Fig. 24.24
17
Fig. 24.25
18
Fig. 24.35
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Bony Fishes Feeding and Evolutionary Ecology

• Feeding modes filter feeders (ex. anchovies),
  grazers (ex. surgeon- fishes), suction-feeding
  planktivores (ex. many damselfishes), piscivores
  (ex. groupers, tunas), crushers (ex. most
  wrasses) most parrotfishes ingest coral and
  digest zooxanthellae goat- fishes detect prey in
  sediment with barbels most butterflyfishes
  ingest coral polyps winnowing (ex. surfperches)
  
• Evolutionary Ecology
• Tunas and billfishes very fast, powerful (cross
  entire oceans) red muscle for endurance (high
  in oxygen and myoglobin) counter-current heat
  exchange, rete-mirabile allow endothermy
  (warm-blooded 2-10 C above ambient) high
  predation rates and high metabolism bills for
  predation (marlin dangerous!)
• Deep-sea fishes adapted for life with little
  food lack muscle counter- illumination
  photophores on ventral surface to match
  downwelling light
• Coloration and Mimicry color patterns involve
  countershading, cryptic coloration, warning
  coloration, species recognition (poster
  coloration), disruptive coloration, mimicry
  (incl. aggressive mimicry)

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Fig. 24.26
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Bony Fishes Schooling, Migrations, and Fisheries

• Schooling behavior grouping with biosocial
  attraction (vs. simple aggregation)
• Coordination with nearest neighbors largely
  mediated via lateral-line sense (experiments
  with blinds, glues, nerve oblation, etc.)
• Reduces predation via confusion effect and
  reduction of predator/prey encounters
• Other functions? Note salmon homing theory (incr.
  success?)
• Migrations
• American and European eels spawn in Sargasso Sea
  (catadromous)
• Salmon (anadromous) adults in ocean migrate
  from river mouth to natal streams via olfaction
  (imprinting) from ocean to river mouth via
  sun- compass, magnetic cues?
• Diurnal migrations ex. blacksmith (note
  ecological importance)
• Fisheries and Aquaculture
• Fish an important source of protein human
  population now 7 billion over- fishing a result
  of increased fishing technology size-limits and
  quotas less effective than reserves (allow fish
  a chance for reproduction) people eating fish
  from lower trophic levels under-utilized
  species (ex. deep-sea forms)
• Aquaculture successful farms include tilapia,
  salmon, shrimp, and lobster later eat fish meal
  (contribute to overfishing) coastal wetlands
  used/spoiled

22
Fig. 33.22
23
Fig. 24.33
24
? Fig. 24.37
Fig. 24.34
25
Fig. 24.38