Term
| What are gastric vs non-gastric fish? |
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Definition
gastric have a stomach, secreting HCl
non-gastric don't have a stomach or any other HCl-secreting organ |
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Term
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Definition
| whiskers on catfish, act as sensors in their environment |
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Term
| Describe how dental strutures vary between fish? |
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Definition
some are very small, face backwards to keep prey from escaping
some are very primitive but sharp, can grab prey, punch holes in crustaeans
some are highly organized like mammals' |
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Term
| What are pharyngeal teeth? |
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Definition
calcified structures in the pharynx of the animal, extremely sharp and abrasive
tillapia have these, which allow them to rip open cell walls of the algae they consume |
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Term
| How do filter-feeders take in food? |
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Definition
| have gill rakers, which act like a sieve to remove water and retain prey |
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Term
| Describe the structure of the oesophagus in fish |
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Definition
-many goblet cells to lubricate and moisten food
-some fish have muscles to allow them to spit out undesired food
-some fish have taste buds in oesophagus
-columnar cells to help with salt excretion (esp in sea water fish) |
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Term
| Why is GIT development especially important in fish? |
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Definition
| fish in larval stages do not have the same digestive enzymes, absorptive capacities as juveline and adult fish so need very different diets |
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Term
| When is the GIT operating at 'full capability'? When do digestive capabilities decrease again? |
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Definition
once juvenile period is reached
senile period, enzyme activity decreases |
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Term
| What portion of the stomach acts similar to a gizzard? |
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Definition
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Term
| What are oxynticopeptic cells? |
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Definition
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Term
| Why is it thought that in many cases,the stomach is not truly essential for fish? |
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Definition
| it develops very late, not all fish have a stomach |
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Term
| Which develops earlier, stomach or intestine? |
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Definition
intestine
most of digestion takes place here |
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Term
| What is the limiting factor for protein digestibility in larvae? |
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Definition
digestion NOT absorption
-have limited enzyme activity |
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Term
| Why would we feed hydrolyzed protein? Is there such thing as too much? |
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Definition
providing some hydrolyzed protein can improve digestibility, but there is no advantage to feeding 100% hydrolyzed protein
benefits exist in feeding some intact protein that can't be digested, helps their system to develop as they grow (larvae) |
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Term
True or False
The pancreas is active almost immediately |
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Definition
| true, at hatching time the main endocrine functions are in working order |
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Term
| What stimulates amylase activity? What causes it to drop off as fish age, post-hatching? |
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Definition
not sure. know it's not food ingestion because amylase is present before fish are able to open their mouths
as protein mass of fish increases, specific activity of amylase decreases |
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Term
| What is the goal in feeding larvae? |
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Definition
| switch them from live prey to more cost effective diets (e.g. pellets/granules) as soon as possible without compromising growth |
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Term
Why do larvae do better with some amount of live
(natural) prey than on solely dry diet early stages? |
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Definition
-GIT enzyme production & function not fully developed
-live prey contributes some digestive enzymes/hormones
-live prey more palatable, perceived as food
-live prey contains nutrients dry feeds are limited in
-live prey contain readily absorbable nutrients
-complex nutrients in live prey stimulate development/maturation |
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