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
• Poikilothermic
• Fins
• Scales

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Drag Reduction Features in Fish

• Fusiform body shape
• Reduction of body wave amplitude
• Reduction of surface area
• Boundary layer modifications

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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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Ostracoderms

• Class Pteraspidomorphi (sp. diplorhina two
  nares)
• they literally had two separate olfactory bulbs
  in the brain.
• those with a different shell, i.e. dermal armor

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Placoderms - earliest gnathostomes(jawed
vertebrates)

• True jaws more food!
• Paired fins more food!

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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 Elasmobranch Traits

• cartilaginous skeleton
• no swim bladder
• heterocercal tail
• placoid denticles - scales and teeth
• spiracles present with 5-7 gill slits (no
  operculum)
• urea retained for osmoregulation
• spiral valve in intestine
• males have claspers, internal fertilization
• oviparous, ovoviviparous, viviparous
• teeth in rows, are constantly replaced

Elasmobranch plate or strap gill
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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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• Spotted ratfish Hydrolagus colliei
• Family chimaeridae
• Identification Broad, flat, duckbill shaped
  snout containing incisor shaped teeth. Prominent,
  venomous spine at leading edge of  dorsal fin.
  Tapering tail constitutes almost half overall
  length. Coloration  brown or grey with white
  spots. Skin smooth and scaleless. Can give off an
  iridescent, silvery sheen.  Fins grey or dark.
• Size up to 97cm in length.

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Boneless vs.Bony
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Placoid scales
Found in sharks and rays, and can vary greatly in
external appearance. They do not increase in size
as the fish grows, instead new scales are added.
Placoid scales are often referred to as
denticles. Placoid scales consist of a flattened
rectangular base plate which is embedded in the
fish, and variously developed structures, such as
spines, which project posteriorly on the surface.
The spines give many species a rough texture.
Placoid scales of the Broadnose Sevengill Shark.
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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, no
ctenii. (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
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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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Skeletal Fish Muscle

• Essentially three types of fish muscle red,
  white, pink.
• Red muscle (oxidative) Highly vascularized,
  myoglobin containing tissue used during sustained
  swimming. Small diameter and high blood volume
  rich O2 supply! Presence leads to strong flavor
  in some fishes (tuna).
• White muscle (glycolytic) Little
  vascularization. Used during sprint swimming.
  Large diameter fibers.
• Pink muscle This one is sort of in between red
  and white. Serves in sustained swimming, but not
  to the extent that red muscle is used.

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Swimming Styles Body waves Anguilliform
(eel-like)
Lateral curvature in spine and musculature that
moves in a posterior direction
Start lateral displacement of head, and then
passage of this displacement along the body axis
to the tail
Result backward-facing wall of body pushing
against the water
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Swimming Styles Partial body waves (Sub)
Carangiform, Thunniform (tuna-like)
Body wave begins posterior to head and increases
with amplitude as it moves posteriorly Redu
ced drag compared to full body wave
swimming Wave STARTS at the caudal peducle
(deeply forked, lunate)
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Swimming Styles Caudal peduncle/fin beats
Ostraciform (boxfish-like and puffer-like)
Sculling action of caudal finlike rowing No
body waves - body remains rigid - useful for
odd-shaped fishes
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Swimming Styles Medial fin wavesAmiiform -
bowfin-like
Body rigid, but medial fins generate posterior
waves (forward) or anterior (reverse) Good for
stalking or moving without disrupting body
musculature that serves as electric organ
(knifefish) Also used for sculling -
triggerfish others
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Swimming StylesPectoral fin beats Labriform
wrasse-likeSimilar to rowing
laterally-positioned pectoral fins- often
includes feathering as wellEspecially useful
for fine maneuveringe.g. by deep-bodied fishes
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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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Similar to Darwins finches, different shaped
mouths permit specialization on many prey items.
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Digestive SystemsCartilagenousvs.Teleost
(bony)
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Fish circulation is a closed system. Heart pumps
blood through a loop of arteries, veins, and
capillaries.
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Gills the best wayto gain oxygen (O2)from an
enviroment where its concentrationis already
very low.Counter-currentcirculation permits O2
to diffuse from high tolow concentration,
evenacross venous tissueafter most O2 has
beenremoved from the waterby gills.
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Salt BalanceRevisitedRemFreshwater
fishsalt inside fish gt salt outside
Saltwater fishsalt inside lt salt outside
fish
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Structure of Lateralis Canals

• Epidermal tunnel
• Pores open from canal to skin surface
• Neuromasts distributed within tunnel
• Fluid in tunnel is more viscous than water
  therefore, more resistant to flow

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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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Fish Migrations food, spawning
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Migration for some salmon is a one-way trip!
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Freshwater eels, Anguilla rostrata are at the
extreme end of migratory patterns, taking an
entire life to make the round trip. Adults spend
15 years in fresh water before making the return
trip to spawning grounds.
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Reproduction in Fishes
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Reproductive traits and life-history patterns

• Mating systems
• Promiscuous - both sexes with multiple partners -
  most (common)
• Polygynous - males with multiple mates (cichlids)
• Polyandry - females with multiple mates few
  (Anglerfish, males parasitize females,
  clownfish)
• Monogamy - mating pair remains together over
  time, long gestation of young (some cichlids,
  seahorses, pipefish)

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Courtship/ritualistic displays are patterns of
behavior observed in many fish.
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Some marine fish have specialized reproductive
organs.
Claspers in elasmobranchs male reproductive organ
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Egg laying (ovipary) in sharks, is a common
menthod of fish reproduction.
swell shark egg, Cephaloscyllium ventriosum
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