esophagus
contains mucous cells to lubricate passage
stomach
-many fish have a true stomach
(secretes pepsin and HCL)
-herbivores and omnivorous fish often lack a stomach
(lack pepsin and produce much amylase)
-some fish have a muscular gizzard for grinding food
pyloric caeca
found in some fish
blind pouches off of the juncture of the stomach and small intestine
secrete trypsin in some lipase in others
pancreas
may be a compact organ or diffusely located in mesenteries around intestines
primary site of lipase production
also trypsin (works in alkaline environment of intestines)
also primary site of carybohydrases (amylase)
intestines
produce some enzymes
absorbtion occurs in intestine and similar to what happens in mammals
gill raker adaptations for different food habitats
-each gill arch is specialized for different modes of feeding
-sunfish have great variation in gill rakers
variation in gill rakers
-shortest and stubbiest rakers are in redear sunfish
-short, stout, widely spaces (large mouth bass)
-prevent prey from escaping through the gills, and partially descale prey
-intermediate lenght in gill rakers (bluegill)
-longest finest gill rakers (ex.
spiral valve
surface area of the intestines is increased in sharks and some primitive bony fishes
fish that have a spiral valve
sharks
primitive species
sturgeons
paddlefish
what is the function of the spiral valve
surface area of the intestine is increased
gut length in herbivores, carnivores and omnivores
carnivores- .7-.9
omnivores- 1.1-2.2
herbivores- 5.4-28.7
piscivore
carnivorous animal which eats primarily fish
excretion of nitrogenous wastes
teleosts-excrete most nitrogenous wastes as ammonia.
sharks and coelacanth excrete mainly ureas
where are the excreted
almost all ammonia is excreted from gills
forms of nitrogenous wastes
ammonia and urea
omnivore
eats food of both plant and animal origin
herbivore
feed on plants
carnivore
feeds on flesh
pepsin
chief digestive enzyme in the stomach, breaks down proteins into polypeptides
monophagous
eats only one type of food
ammoniotelic
excrete nitrogenous waste in the form of ammonia
factors affecting fish growth
principal factors controlling anabolic processes are hormones from the pituitary and gonads
abiotic factors
temperature
dissolved oxygen
ammonia
slainity
competition
food availability and quality
photoperiod
age and maturity
effects of exercise conditioning
better food conversion efficiency
increased GH levels
increased protein synthesis rates
decreased antgonistic behavior
decreased stress levels
condition factor (K)
conditions of "plumpness"
often used by fisheries biologists to assess the health of a population
high K values mean food is probably readily available
factors controlling anabolic processes
hormones from pituitary gland
thyroid and gonadal steroid hromones increase growth in most
endocrine disrupting chemicals (EDC)
are hormone-mimicking compounds that are often persisitent in the environment, especially in food chains
abiotic factors
can determine which species of organisms will survive in a given environment
nonliving condition or thing, as climate or habitat that influence or affects an ecosystem and the organism in it
K
often used by fisheries biologists to assess the health of a population. Higher K values mean food is probably readily available
anabolic processes
chmical reactions that synthesize molecules in metabolish
circuli
cell additions occur over time at a fixed rate forming growth rings
cells additions occur over time at a fixed rate forming growth rings call circuli. closely spaced circuli form in the winter producing an annual variation in the circuli pattern called an
types of reproductive categories
sneaker males are common in salmon and trout. sneak into spawning area and release sperm simultaneously with a mated pair
satellite males are a small male hovers above a nest and slowly descends into it to release sperm while a pair is spawning
intormittent organs in live bearers
found in fishes with internal fertilization
poecilids anal fin rays
sharks pelvic fins have claspers
surfperches have thickened anal spines
pelagic spawners
mainly found in marine species
eggs, embryos and larvae are buoyant
main advantage of pelagic spawning is widespread dispersal by currents
mortality is high, females produce large numbers of eggs
some benthic fish associated with coral reefs rise to the s
nest spawners
construct some sort of structure, cavity or pit in which the eggs are laid and defended
brood hiders
most are benthic spawners that bury their eggs
nest guarders
guard developing embryos and sometimes larvae
have territoriality and sometimes courtship
in the most, the males guard
in cichlids,, females or both male and female guard
ovoviviparous forms
obligate internal bearers
monogamy
one male and one female mate exclusively
polygyny
one male mating with several females
promiscuity
many males and females mate simultaneously
polyandry
one female seeks to mate with several males
sexual dichromatism
color difference between sexes
usually a seasonal phenomenon in most species
many tropical fish show permanent dichromatism
path taken by sperm cells in teleosts and sharks
teleosts- have seperate sperm ducts
sharks- sperm pass through duct share with the kidnesy and then are stored in seminal vesical before release
embyonic period
lasts from fertilization to larval stage
embryonic period doesnt end with hatching
larval period
begins when the fish can take in food and ends when the axial skeleton is formed and the embryonic mediam fin fold is gone
many marine fishes have long larval stages
freshwater- many have pelagic larvae
stem fishes typically have benthic larvae
juvenile period
begins when organ systems are fully formed and fins are fully formed
miniature adults in appearance
adult period
begins when gonads are mature
senescent period
growth is stopped and gonads are degenerate