Marine Fishes

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Marine Fishes
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What is a fish??

• Classic definition
• -Any of numerous cold-blooded aquatic
  vertebrates of the
• superclass Pisces, characteristically having
  fins, gills, and a
• streamlined body and including specifically,
  and...
• -Any of the class Osteichthyes, having a bony
  skeleton, and...
• -Any of the class Chondrichthyes, having a
  cartilaginous
• skeleton and including the sharks, rays, and
  skates.
• Although this is all accurate...we will find
  that fish are
• considerably MORE!!

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Fish similarities...

• Vertebrate ( chordate)
• Gills
• Fins
• Scales

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What is a fusiform body shape?

• pointed leading edge
• maximum depth 1/3 body length back from head
• posterior taper
• caudal fin interrupts ideal fusiform shape

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Hagfish (Agnatha) jawless fish
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Lamprey

• Predatory/parasitic
• Rasping teeth

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Parasitism of Great Lakes fishes
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Cartilagenous Fishes(Sharks, Skates and Rays)
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Distinguishing Traits

• cartilaginous skeleton
• no swim bladder
• heterocercal tail
• scales and teeth
• spiracles present with 5-7 gill slits
• males have claspers, internal fertilization
• teeth in rows, are constantly replaced

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Sharks exhibit extreme variability in size, shape
and abilities.
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Nearly 850 spp. of sharks, 350 exhibit typical
body morphology.
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Variations on this theme are common.
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• Carchariniformes basking sharks, filter feeder

Cetorhinus maximus
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Mako
Great White
Isurus oxyrinchus
Lamniformes - mackerel, mako, white
sharks -carnivores
Great White, Carcharodon carcharias
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Skates and rays spend most of their lives near
(on) the ocean floor eating molluscs, squid, and
small fish.
Yellow stingray, Urolophus jamaicensis
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• Like sharks, skates and rays come in
• many shapes and sizes.

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• Blue spotted ray, Taeniura lymma

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Skates (order Rajiformes) pelvic fin divided into two lobes  tail relatively stocky, no spine 
Rays (order Myliobatiformes) each pelvic fin with one lobe  tail relatively slender to whip-like spine
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Boneless vs.Bony
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Cycloid and Ctenoid Scales
Found in bony fishes (the Teleostei). Overlapping
flexibility, over cosmoid or ganoid scales.

Cycloid scalessmooth posterior margin. (Greek
"cyclo or circle.)
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Fish form and functionshow a high degreeof
variation.
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Coloration is also veryimportant in fish.Here
a stonefish disappearsamid the coral
background.Chromatophores, specializedpigment
cells within itsskin provide protective
coloration.
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Disruptive Coloration (Camo!)

• Disrupt the outline of the fish

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Countershading

• Being dark on top, light on bottom Look like
  substrate from above Look like water surface
  from below

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Warning coloration! May indicate poisonous amimal.
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Fish Locomotion

• Primary forces involved in fish swimming
• Thrust - force that propels forward
• Drag - friction produced from passing an object
  through a medium
• Gravity force from earths magnetic pull
  (partially counterbalanced by density of
  water)
• Lift - upward force that counteracts gravity

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Fish Feeding - function

• Herbivores
• lt 5 of all bony fishes, no cartilaginous fishes
• browsers - selective - eat only the plant
• grazers - less selective - include sediments
• Detritivores
• 5 - 10 of all species
• feed on decomposing organic matter

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Fish Feeding - function, cont.

• Carnivores
• zooplanktivores
• suction feeding
• ram feeding
• benthic invertebrate feeders
• graspers
• pickers
• sorters
• crushers

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Fish Feeding - function, cont.

• Carnivores, cont.
• fish feeders
• active pursuit
• stalking
• ambushing
• luring

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Fish feeding behavior

• Fish feeding behavior integrates morphology with
  perception to obtain food
• Search
• --gt Detection
• --gt Pursuit
• --gt Capture
• --gt Ingestion

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Feeding behavior

• Fish show versatility in prey choice and
  ingestion
• Behavior tightly linked to morphology
• (co-evolution)

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Lateral line also aids in navigation in close
quarters.
Damselfish, Chromis spp.
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Predator avoidance
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Migration for some salmon is a one-way trip!