Osteichthyes: Bony Fish - Yolamrsgallegoswebsite.yolasite.com/resources/Osteichthyes.pdfAquaculture...
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Transcript of Osteichthyes: Bony Fish - Yolamrsgallegoswebsite.yolasite.com/resources/Osteichthyes.pdfAquaculture...
Dorsal
Anatomical terminology
Ventral
Posterior or caudal
Anterior Lateral Lateral
Used for relating different parts….Eye is posterior to the mouth
Conversely the mouth is anterior to the eye
External Anatomy
Sail fish (Istiophorus platypterus)
American eel (Anguilla rostrata)
Fins Mouth Scales
White sucker (Catostomus commersonii)
River hatchetfish (Gasteropelecus sternicla )
Longnose gar (Lepisosteus osseus)
Great white shark (Carcharodon carcharias)
Spines • Rigid
• Often for defense
Rays • Flexible
• Often branched
• Mainly for support
Fisheries ecologists use both spines & rays for identification and aging!
Heterocercal • Tip of vertebral column turns upward
• Epicercal: dorsal lobe larger (sturgeon)
• Hypocercal: ventral lobe longer (flying fish)
Protocercal
• Extends around vertebral column
• Embryonic fish; hagfish
Homocercal • Vertebral column stops short of caudal fin,
which is supported by bony rays
• Symmetrical
Diphycercal • 3 lobed; lungfish and coelacanth
• Vertebral column extends to end of caudal fin, dividing into symmetrical parts
Placoid: sharks and
rays
decrease drag.
Ganoid: bowfin, paddlefish, gar, sturgeon
Armor-like plates for protection
Cycloid and Ctenoid: most bony fishes (teleosts) • Overlapping = Flexibility, reduced drag
• Both grow in concentric rings Cycloid: smooth outer edge, soft-rayed
fish (e.g., salmon)
Ctenoid: “toothed” outer edge, spiny fish (e.g., bass)
Body Shape
• Related to lifestyle
• Fusiform (streamlined body)-helps move through water easy, fast swimmer
-Ex: Sharks, Tuna, Marlins
Body Shape Cont’d
• Laterally Compressed- leisurely swimming around coral/kelp
-Ex: Angelfish, damselfish, butterfly fish
• Elongated body- live in narrow spaces -Ex: moray eels, trumpet fish, pipefish • Round- porcupine fish
• Flatfish- actually laterally compressed. Adapted to live on bottom
• Lie on side, both eyes on top
– (born w/ eyes on each side)
FLOUNDER SOLE
HALIBUT
Locomotion • Rhythmic side to side motion
• swim bladder for buoyancy and lift
-pectoral fins used to hover and swim backwards
Fish Circulation
• Fish heart has 2 chambers
• Single loop circulation
• Blood flows into gills, picks up O2, goes
to the body, returns to the heart.
• Gills are the main
site of gas exchange
in almost all fishes.
• The gills consist of bony or
stiffened arches (cartilage) that
anchor pairs of gill filaments.
Numerous lamellae protrude from both sides of each filament and are the primary sites of gas exchange.
Microscopic gill structure: showing gill filament and lamellae (Red blood cells
evident.)
Lots of surface area…Oxygen diffuses right into blood stream!
• Water flows over gills as fish opens mouth.
• Water flows OPPOSITE direction of blood flow
(countercurrent system)
Higher conc. of O2 in water than in blood…O2 diffuses from the
water into the blood.
WHAT WOULD HAPPEN IF THEY FLOWED IN SAME
DIRECTION? (Co-Current)?????
COUNTER-CURRENT
So, they efficiently extract oxygen by….
• Short diffusion distance at gill site
• Large surface area for diffusion at gill site
• Counter current exchange of gases at gill site
• Large volume of water passes over gills
Why school? • Protects against predation
• Causes confusion, encircle a predator
• Hard to pick out one
• Maybe… swimming efficiency (fish in front reduces water resistance)
Hermaphrodites • Some marine hamlet fish are
hermaphrodites
– Although they could fertilize own eggs, they still cross fertilize
• Found in many deep sea fish when mates are hard to find
Sex Reversal • Most prevalent in some sea basses, grouper,
parrotfish, wrasses, clown
• male female (protandry)
female male (protogyny)
• controlled by sex hormones but triggered by social cues – i.e.: absence of dominant female in
hierarchy
REDUCING BYCATCH
• Dolphins and tuna known to swim together and caught in purse seines
– Backdown method for “dolphin safe tuna”
• Turtles often caught in trawlers
– Turtle Excluder Devices (TED)
Overfishing
• Growing world population
• Large scale fishing methods
• Improved technology
• Competition for profit
• No recovery time
• Depletion of natural populations
Aquaculture (fish farms)
• Marine aquaculture refers to the culturing of species that live in the ocean. U.S. marine aquaculture primarily produces oysters, clams, mussels, shrimp, and salmon. Marine aquaculture can take place in the ocean (that is, in cages, on the seafloor, or suspended in the water column) or in on-land, manmade systems such as ponds or tanks. Recirculating aquaculture systems that reduce, reuse, and recycle water and waste can support some marine species.
• Freshwater aquaculture produces species that are native to rivers, lakes, and streams. U.S. freshwater aquaculture is dominated by catfish but also produces trout, tilapia, and bass. Freshwater aquaculture takes place primarily in ponds and in on-land, manmade systems such as recirculating aquaculture systems.
-NOAA