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Fisiologi Biota Akuatik FeedingDigestion.ppt
- 1. Feeding & Food Processing 1. Structure(review) 2. Function (behavior, physiology) 3. Nutritional needs 4. Digestive efficiency
- 2. Food capture Food capture Mouth and pharyngeal cavity Jaws Jaws Teeth - jaw, mouth, pharyngeal Teeth - jaw, mouth, pharyngeal Gill rakers Gill rakers
- 3. Fish Feeding -function Herbivores < 5% of all bony fishes, < 5% of all bony fishes, no cartilaginous fishes no cartilaginous fishes browsers - selective - browsers - selective - eat only the plant eat only the plant grazers - less grazers - less selective - include selective - include sediments sediments Detritivores 5 - 10% of all species 5 - 10% of all species feed on decomposing feed on decomposing organic matter organic matter
- 4. Fish Feeding –function Carnivores zooplanktivores zooplanktivores suction feeding suction feeding ram feeding ram feeding benthic benthic invertebrate invertebrate feeders feeders graspers graspers pickers pickers sorters sorters crushers crushers
- 5. Fish Feeding –function More Carnivores fish feeders fish feeders active pursuit active pursuit stalking stalking ambushing ambushing luring luring
- 6. Fish feeding behavior Fish feeding behavior integrates morphology with perception to obtain food: Search --> Detection --> Pursuit --> Search --> Detection --> Pursuit --> Capture --> Ingestion Capture --> Ingestion
- 7. Feeding behavior Fish showversatility in prey choice and ingestion Behavior tightly linked to morphology (co-evolution) (co-evolution)
- 8. Fish feeding behavior Behavior tends to be optimizing when choices are available Optimal Optimal = maximize = maximize benefit:cost ratio benefit:cost ratio More for less! More for less! Select the prey that yields the Select the prey that yields the greatest energetic or nutrient greatest energetic or nutrient “return” on the energy invested in “return” on the energy invested in search, pursuit, capture, and search, pursuit, capture, and ingestion ingestion
- 9. Fish digestive physiology After ingestion of food, gut is responsible for: Digestion Digestion - breaking down food into small, - breaking down food into small, simple molecules simple molecules involves use of acids, enzymes involves use of acids, enzymes Absorption Absorption - taking molecules into blood - taking molecules into blood diffusion into mucosal cells diffusion into mucosal cells phagocytosis/pinocytosis by mucosal cells phagocytosis/pinocytosis by mucosal cells active transport via carrier molecules active transport via carrier molecules
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- 11. Fish Digestion Twomajor groups: w/stomach, w/out w/out stomach: cyprinids (carps) w/stomach: cold-water salmonids, warm- water catfish, tilapia, eels, grouper note: all “pure” predators have a stomach and teeth relative gut length (RGL): gut:body length high RGL = species consuming detritus, algae (high proportion of indigestible matter)
- 12. Relative Gut Length SpeciesFeeding RGL Labeo horie Algae, detritus 15.5 Garra dembensis Algae, inverts 4.5 Barbus sharpei Plants 2.8-3.1 Chelethiops elongatus Zooplankton 0.7 Chela bacaila Carnivorous 0.9
- 13. Fish Digestive Morphology: MajorDivisions Mouth Esophagus Pharynx Stomach Intestine Rectum Secretory glands (liver and pancreas) often difficult to distinguish
- 14. Gastrointestinal Tract Gastrointestinal Tract Esophagus Stomach large in carnivores, large in carnivores, small in small in herbivores/omnivo herbivores/omnivo res res Pyloric caeca Intestine short in carnivores, short in carnivores, long in herbivores- long in herbivores- omnivores omnivores Anus - separate from urogenital pore
- 15. GI Tract- SecretoryGlands GI Tract- Secretory Glands Liver produces bile (lipolysis) produces bile (lipolysis) stores glycogen stores glycogen stores lipids stores lipids Pancreas digestive enzymes digestive enzymes proteases - protein proteases - protein breakdown breakdown amylases - starch amylases - starch breakdown breakdown chitinases - chitin chitinases - chitin breakdown breakdown lipases - lipid breakdown lipases - lipid breakdown
- 16. Digestive Anatomy: Mouth/Esophagus Channelcatfish: large mouth/esophagus, capture prey, slightly predaceous, mouth has no teeth, no gizzard/cardiac sphincter Common carp: small mouth for bottom feeding, pharyngeal teeth, grinds food Tilapia: combination of bottom feeder, predator, efficient plankton feeder, uses gill rakers, pharyngeal mucous
- 17. Digestive Anatomy: Stomach Channelcatfish: have true stomach that secretes HCl and pepsinogen (enzyme) Common carp: no stomach; however, “bulb” at anterior end of digestive tract, bile and pancreatic secretions empty into intestine posterior to cardiac sphincter, no secretion of gastrin (low pH) Tilapia: modified stomach, secretes HCl, well-defined pocket, pH varies w/digestal flow, has pyloric sphincter
- 18. Digestive Anatomy: Intestine Channelcatfish: length less than whole body, no large/small version, slightly basic pH, digestive secretions, nutrient absorption, many folds for absorption Common carp: digestive tract is 3x whole body length, similar in activity to that of channel catfish Tilapia: tract is 6-8x that of body length, activities similar to that of other species
- 19. Digestive Anatomy: Liver andPancreas Both organs produce digestive secretions Liver produces bile but is also the primary organ for synthesis, detoxification and storage of many nutrients Pancreas is primary source of digestive enzymes in most animals It also produces zymogens (precursors to enzymes)
- 20. Fish Digestive Physiology Digestion is accomplished in Stomach Stomach low pH - HCl, other acids (2.0 for some low pH - HCl, other acids (2.0 for some tilapia!) tilapia!) proteolytic enzymes (mostly pepsin) proteolytic enzymes (mostly pepsin)
- 21. Digestive Processes: Stomach Catfishas an example - its digestive processes are similar to that of most monogastric animals Food enters stomach, neural and hormonal processes stimulate digestive secretions As stomach distends, parietal cells in lining secrete gastrin, assisting in digestion Gastrin converts the zymogen pepsinogen to pepsin (a major proteolytic enzyme) Some fish have cirulein instead of gastrin
- 22. Digestive Processes: Stomach Flowof digesta out of stomach is controlled by the pyloric sphincter Pepsin has pH optimum and lyses protein into small peptides for easier absorption Minerals are solubilized; however, no lipid or COH is modified Mixture of gastric juices, digesta, mucous is known as chyme
- 23. Fish Digestive Physiology Digestion is accomplished in Stomach Stomach Intestine Intestine alkaline pH (7.0 - 9.0) alkaline pH (7.0 - 9.0) proteolytic enzymes - from pancreas & proteolytic enzymes - from pancreas & intestine intestine amylases (carbohydrate digestion) - from amylases (carbohydrate digestion) - from pancreas & intestine pancreas & intestine lipases (lipid digestion) - from pancreas & lipases (lipid digestion) - from pancreas & liver (gall bladder, bile duct) liver (gall bladder, bile duct)
- 24. Digestive Processes: Intestine Chymeentering the small intestine stimulates secretions from the pancreas and gall bladder (bile) Bile contains salts, cholesterol, phospholipids, pigments, etc. Pancreatic secretions include bicarbonates which buffer acidity of the chyme Zymogens for proteins, COH, lipids, chitin and nucleotides are secreted e.g., enterokinase (trypsinogen --> trypsin) Others: chymotrypsin, carboxypeptidase, aminopeptidase, chitinase
- 25. Digestive Processes: Intestine Digestionof carbohydrates is via amylase, which hydrolyzes starch Others: nuclease, lipase Cellulase: interesting in that it is not secreted by pancreas, but rather produced by gut bacteria Note: intestinal mucosa also secretes digestive enzymes
- 26. Fish digestive physiology Absorption is accomplished in Intestine Intestine diffusion into mucosal cells diffusion into mucosal cells phagocytosis/pinocytosis by mucosal cells phagocytosis/pinocytosis by mucosal cells active transport via carrier molecules active transport via carrier molecules
- 27. Digestive processes: Absorption Mostnutrient absorption occurs in the intestine Cross-section of the intestinal luma shows that it is highly convoluted, increasing surface area Absorption through membrane is either by passive diffusion (concentration gradient) Or by active transport (requires ATP) Or via pinocytosis (particle engulfed) Nutrients absorbed by passive diffusion include: electrolytes, monosaccharides, some vitamins, smaller amino acids
- 28. Digestive processes: absorption Proteinsare absorbed primarily as amino acids, dipeptides or tripeptides triglycerides are absorbed as micelles COH’s absorbed as monosaccharides (e.g., glucose, except for crustaceans) calcium and phosphorus are usually complexed together for absorption all nutrients, excluding some lipids, are absorbed from the intestine via the hepatic portal vein to the liver
- 29. Summary of Digestive Enzymes Site/TypeFluid/enzyme Function/notes Stomach HCl Reduces gut pH, pepsiongen Gastric secretions Zymogen, pepsinogen, HCl Amylase Lipase Esterase Chitinase Proteolysis COH’s Lipids Esters Chitin Pancreas HCO3 Proteases Amylase Lipase Chitinase Neutralizes HCl Cleave peptide linkages COH’s Lipids Chitin Liver/bile Bile salts, cholestrol Increase pH, emulsify lipids Intestine Aminopeptidases Lecithinase Split nucleosides Phospholipids to glycerol + fatty acids
- 30. Fish Nutritional Needs High protein diet: Carnivores - 40 - 55% protein needed Carnivores - 40 - 55% protein needed Omnivores - 28 - 35% protein needed Omnivores - 28 - 35% protein needed Birds & mammals - 12 - 25% protein needed Birds & mammals - 12 - 25% protein needed 10 essential amino acids (PVT. TIM HALL) 10 essential amino acids (PVT. TIM HALL)
- 31. Fish Nutritional Needs High protein diet Why so high? Proteins needed for growth of new tissue Proteins needed for growth of new tissue Proteins moderately energy-dense (don’t Proteins moderately energy-dense (don’t need dense source - ectotherms, low gravity) need dense source - ectotherms, low gravity) Few side-effects - ease of NH Few side-effects - ease of NH4 4 + + excretion excretion
- 32. Nutritional efficiency in fishes Fish more efficient than other vertebrates: Conversion factor = kg feed required Conversion factor = kg feed required to produce 1 kg growth in fish flesh to produce 1 kg growth in fish flesh Fishes: 1.7 - 5.0 Fishes: 1.7 - 5.0 Birds & mammals: 5.0 - 15.0 Birds & mammals: 5.0 - 15.0
- 33. Nutritional efficiency in fishes Fish more efficient than other vertebrates Why? Ectothermy vs. endothermy Ectothermy vs. endothermy Energy/matter required to Energy/matter required to counterbalance gravity counterbalance gravity Bias of a high-protein diet Bias of a high-protein diet
- 34. Nutritional efficiency Maintenanceration (MR) = the amount of food needed to remain alive, with no growth or reproduction (% body wt./day) MR is temperature-dependent MR increases as temperature increases MR increases as temperature increases MR is size-dependent MR decreases as size increases MR decreases as size increases