Fish biology Flashcards
Fancy word for fish biology.
ichthyology
What phylum do fish belong to?
chordata
How many fish species are there?
approx. 30-35 000
Distribution of fish types in various waters.
60% marine
40% freshwater
Most are continental meaning in fresh water “on land” or in the sea close to the coast
COASTS ARE GOOD FOR FISH AS THEY ARE RICH IN NUTRIENTS
SUCH AS NITRATES AND PHOSPHATES FROM RIVERS, UPWELLING,
AERATION FROM THE SURF AND TIDE AND THE SUNLIGHT (UV)
Can fish live in hot springs?
cyprinodon fish can, temps of up to 45’C
OTHERS ARE FOUND IN THE ANTARCTIC SEAS, SUCH AS
CHAENOCEPHALUS, LESS THAN 0°C (ANTIFREEZE LIQUID)
most common fish shape
fusiform aka torpedo-shaped but rounded like flounders are also common
smallest fish species?
and biggest?
pygmy goby adult max 12 mm long, 1.5 g
whale shark is biggest, up to 18m, over 20 tons
3 big classes of fish:
Main diff between the classes are diff types of skeletons.
- Agnatha (jawless fishes) e.g. hagfish - only a notochord
- Chondrichthyes (cartilaginous) e.g. shark, rays - have notochord in vertebrae but otherwise are cartilaginous
- Osteichthyes (bony fish) e.g. every other species - real bones
3a. Actinopterygii (ray finned fish) e.g. sturgeons
Fish fins are either
median or paired
When do fish stop growing?
they grow up until they die
Scale rings form like tree rings.
Otoliths / ear bones may give you a clue as to age.
Where does the coloring of fish come from?
Scales are colorless, the color comes from the structures beneath the scales.
Not all fish species have scales e.g. catfish
Some only have scale patches e.g. carp
Scales are fitted in a certain pattern. Whats it called.
Either imbricate (overlapping like shingles), or
mosaic (very close together or barely separated).
4 basic scale types:
- placoid scales aka dermal denticles
- cosmoid scales
- ganoid scales
- leptoid scales
describe placoid scales aka dermal denticles are found on
sharks, rays
are tooth-like. shark teeth are actually enlarged scales
new scales added with growth
describe cosmoid scales
four-layered bony scales
describe ganoid scales
squarish in shape, single bony layer
found on gars
describe leptoid scales
single layer of bone, found on higher bony fish and occur in 2 forms:
cycloid (circular)
ctenoid (toothed)
Fish muscle types.
red muscle is slow
white muscle is fast
pink muscle is intermediate
Fish heart anatomy.
2-chambered heart, O2 from gills. extract up to 80% of O2 from water.
heart-gills-body
Why is reducing body weight important to fish?
so they can expend less energy to keep at a given depth
fat is less dense than water, some fish are up to 1/3 fat
fish use a gas-filled swim bladder
The size of the swim bladder depends on
the type of water: fresh or marine
swim bladders take up 4-11% of body volume
freshwater is less dense and less buoyant so they need a bigger swim bladder to keep from sinking
auxillary resp. structures in fish (5)
skin - O2 can diffuse into dense skin capillaries in some fish
swim bladder - gars have special vascularized ones
lungs - modifed swim bladders in lungfish
mouth - vascularized roof of mouth in eels etc.
gut - vascularized stomach of intestine wall in catfish etc.
The blood of freshwater fish is saltier than
the water in which they live.
The blood of sharks is saltier than the sea.
osmotic pressure causes water to diffuse into fish. how do they eliminate excess water?
they produce very dilute urine
a gain in water means a loss in salt so they absorb salt from water with their gills
