Marine Vertebrates:

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Marine Vertebrates Fishes (part 2)
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Fishes

• Phylum Chordata
• Subphylum Vertebrata
• 3 Classes
• Class Agnatha (jawless fishes)
• Class Chondrichthyes (cartilaginous fishes)
• Class Osteichthyes (bony fishes)

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Fishes - Anatomy

• Cartilaginous fishes
• Ventral mouth
• Heterocercal tail (caudal fin)
• Placoid scales

dermal denticles
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Fishes - Anatomy

• Bony fishes
• Terminal mouth
• Homocercal tail
• Cycloid or ctenoid scales

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Fishes - Anatomy

• Cartilaginous fish skeleton

http//www.marinebiodiversity.ca/shark/english/ima
ges/porbeagle20skeleton20for20web.jpg
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Fishes - Anatomy

• Bony fish skeleton

http//www.infovisual.info/02/img_en/03420skeleto
n20of20a20fish.jpg
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Fishes - Buoyancy

• Bony fish swim bladder (gas)
• Cartilaginous fish
• Swim, get lift from stiff fins
• Large, oil-filled liver
• Cartilage half as dense as bone

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Fishes - Locomotion

• Muscle up to 75 of body weight
• Muscle bands myomeres (flake when cooked)
• Red muscle sustained swimming
• White muscle burst swimming

http//www.buschgardens.org/infobooks/BonyFish/ima
ges/muscle.gif
http//www.earthlife.net/fish/muscles.html
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Fishes - Locomotion
Homocercal caudal fins by shape
Slowest ?
? Slow
Fast ?
? Fastest
Heterocercal caudal fins
http//www.buschgardens.org/infobooks/BonyFish/ima
ges/caudalfi.GIF
http//www.dfw.state.or.us/mrp/salmon/FishID/Heter
ocercal.jpg
http//static.howstuffworks.com/gif/willow/flying-
fish-info0.gif
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Fishes - Locomotion
Swimming modes
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Fishes - Locomotion
Built for speed Pacific sailfish has high speed
bursts 70 mph
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Fishes - Respiration
Bony fish (more efficient)
Cartilaginous fish

• 5-7 pairs of gills
• Gill slit openings

• 4 pairs of gills
• Operculum gill cover

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Fishes - Respiration

• Spiracles important for rays when buried

http//elasmodiver.com/images/Cortez-round-stingra
y-04.jpg
http//blogs.southflorida.com/citylink_dansweeney/
Southern_sting_ray.jpg
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Fishes - Respiration

• Gills maximize oxygen diffusion
• High surface area
• Counter-current flow (oxygen concentration of
  water always higher than blood)

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Fishes - Respiration

• Warm-blooded fish
• Epipelagic sharks, tunas, billfishes
• Counter-current flow retains muscle heat
• Body surface stays water temperature
• Body core has elevated temperature

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Fishes - Feeding
Large mouth, tear chunks or swallow fish whole
Small mouth, small prey
Large mouth, filter feeder (plankton)
Small mouth, small prey
Hard beak, graze algae and coral
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Fishes - Feeding

• Largest species
• Whale sharks (up to 60 ft)
• Basking sharks (up to 50 ft)
• Filter feeders (eat plankton)

Whale (Rhincodon typus)
Basking (Cetorhinus maximus)
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Fishes - Digestion
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Fishes - Osmoregulation
Equal solutes by adding urea
Lower solutes, water loss
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Fishes Sensory Organs

• Vision
• Taste buds
• Smell olfactory sacs, nostrils
• Sound inner ear, otoliths (bones)

http//www.marinebiodiversity.ca/otolith/english/i
mages/cod6oto.jpg
http//www.ncdc.noaa.gov/paleo/pubs/andrus2002/oto
lith-md.gif
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Fishes Sensory Organs

• Vibrations lateral line
• (for hearing, too)

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Fishes Sensory Organs

• Electroreception ampullae of Lorenzini
  (cartilaginous fishes only)

small holes
http//www.seaworld.org/infobooks/SharksRays/imag
es/ampullae.gif
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Fishes Schooling

• Use senses to coordinate (vision, sound, lateral
  line)
• Protection from predation
• Safety in numbers
• Visual confusion
• Feeding
• Mating
• Swimming efficiency

http//image03.webshots.com/3/4/24/9/6942409XjGFEF
guyY_ph.jpg
http//image14.webshots.com/14/5/22/94/170152294Gj
ijRv_fs.jpg
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Fishes Reproduction

• Fertilization
• External bony fishes
• Internal cartilaginous

http//www.gloversreef.org/grc/spawning.jpg
http//www.flmnh.ufl.edu/fish/education/questions/
claspers.jpg
http//www.pbs.org/wnet/nature/files/2008/10/286_l
ifeed_behind1.jpg
http//www.charkbait.com/article/Scan5sm.jpg
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Fishes Reproduction

• Development
• Oviparous (most bony fishes, some
  cartilaginous)
• External eggs, yolk

http//www.ufz.de/data/bioindicator-fish-eggs2455.
jpg
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Fishes Reproduction

• Development
• Ovoviviparous
• Internal eggs, yolk, live-birth
• Viviparous
• Internal eggs, nutrition from mother, live-birth

http//www.west.asu.edu/achristie/hsw4kids/animals
/sharks/birtha.jpg
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Fishes Reproduction

• Asexual parthenogenesis (virgin births)
• Very rare
• Female sharks in captivity
• Female offspring (genetic clones)

Bonnethead 2001
Black-tip 2008
http//www.sciencedaily.com/images/2008/10/0810101
73054-large.jpg
http//marinebio.org/upload/_05/Sphyrna_tiburo1.jp
g
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Fishes Reproduction

• Strategies
• Many small eggs (tarpon 100 million eggs each
  spawn)
• Fewer large eggs (more work)

http//www.soc.soton.ac.uk/GDD/hydro/atmu/ecology/
chapter5/sgtmjr.jpg
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Fishes Development

• Planktonic fish larvae

http//www.coralreeffish.com/larvae.htm
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Fishes Development

• Coastal fish use estuaries as nurseries

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Cartilaginous vs. Bony Fishes
Cartilaginous Bony
Scales placoid cycloid, ctenoid
Mouth ventral terminal
Tail lobes unequal (heterocercal) equal (homocercal)
Gills 5-7 pairs, slits 4 pairs, covers
Position in water fins, lower density (cartilage and oily liver) swim bladder
Osmoregulation urea (equal solutes), rectal gland less solutes, gill excretion
Sensory ampullae of Lorenzini, lateral line lateral line
Reproduction (fertilization, development, strategy) internal, variety, fewer offspring external, mostly ovipary more offspring