Lectures 23, 20 Nov 2003Chapter 15, Feeding and DigestionVertebrate PhysiologyECOL 437University of ArizonaFall 2003instr: Kevin Boninet.a.: Bret Pasch1Vertebrate Physiology 4371. Feeding and Digestion (CH15)2. Announcements… -Exams returned next week -Powerpoint preview -Eldon Braun Thanks2FEEDING3FeedingFilter Feeding -baleen whales -flamingoes -planktivorous fish with modified gill rakers -amphibian larvaeFluid Feeding -lampreys -vampire bats (analgesic and anticoagulants)(15-3)4-Jaws, teeth, beaks-Form and function matchedSeizing with mouth etc.Modification fordiet(15-7)Eryx tataricus5(15-8)Modification fordietSeizing with mouth etc.-Form and function matched-Darwin’s Finches in Galapagos6Seizing with mouth etc.Most toothed non-mammalianvertebrates have homodontdentition -Exception: Some snakesViperidae,includingrattlesnakes(15-6)Some snakes also withvenom- hemolytic, neurotoxicEunectes murinus7HelodermaFront FangedHypodermicDuvernoy’s/Venom GlandSolenoglyphProteroglyph ElapidaeViperidaePough et al. 20018Joe SlowinskiMyanmar, BurmaBungarus multicinctusMultibanded Kraitalpha bungarotoxinnicotinic ACh receptor antagonist9… Alethinophidia, Macrostomata, Caenophidia, ColubroideaElapidae(62 genera, 300 species)- Cobras, coral, and sea snakes- venomous- proteroglyph dentitionmaxilla longer than that of vipersmay have teeth posterior to fangrelatively fixed- some with biparental care- most terrestrial are oviparous- most marine are viviparous- corals often mimicked by non-venomous sympatricsMicruroides euryxanthusNaja spp.10Pit Organsmultiple origins - vipers, boas, pythonsinfrared imagePough et al. 2001(pit sensitivity to 0.003 C)11Gastric Brooding Frog Etc.Python regiusRheobatrachus vitellinus12Pough et al. 2001UnidirectionalSuction Feeding13Suction FeedingSalamanders1. Jaws open2. Hyoid apparatus (floor of mouth) drops3. Muscles keep gills closedA few genera asymmetrical- flexible mandible (cartilage)Figure 9-5Pough et al. 2001Cryptobranchus alleganiensis14Suction FeedingAnuransTadpolesunidirectionalspiracle(s)filter feeders - strain - mucusFigure 9-6fPough et al. 2001buccal pharyngealatrialbranchialfiltersStebbins and Cohen, 199515Turtle Suction FeedingBidirectional, no teeth (keratinous beak)1. Compensatory suction - displaced water2. Inertial suction - modified hyobranchial - greater expansionEsophogeal modifications - prevent prey escape - Dermochelys, 5 cm spinesFigure 9-13Pough et al. 200116FeedingChamaeleo jacksonii17Projectile FeedingSalamandersHydromantesDeban et al. 1997abcdretractorprotractor18ScolecophidiansSnake FeedingAncestral Group- small gape- short jaws- many small preyLeptotyphlops (teeth lower only)Mandibular rakingFig. 4-25Pough et al. 200119Cranial KinesisSnake FeedingUnilateral Feeding- two sides of lower jaw (dentary) unfused- intramandibular hingeFig. 9-33Pough et al. 2001- looser streptostylic quadrate20Fig. 9-25Pough et al. 200121~Terrestrial FeedingTurtles -beak shape thickness (durophagic) motion (Gopherus)GeocheloneelephantopusAlligator Snapping TurtleMacroclemys temminckii22Pough et al. 2001Egg Eating (e.g., Dasypeltis)elastic neck skin, few teeth, vent. vertebral processes23Digestive SystemsThree main types:1. Batch reactors (in and out, not in vertebrates)Alimentary Canal2. Continuous-flow/Stirred-tank reactor(in, out when broken down)3. Plug-flow reactorOften 2,3 combined (e.g., stomach and small intestine)24-Food quality-Body Size-Temperature (ectotherms)Digestive SystemsTransit time (time to digest),cost, and anatomy variable:(15-11)(15-12)25Generalized DigestiveSystem(15-13)12341234Salivary glands(mucin) tolubricateTongue forchemoreception26(15-16)27Generalized DigestiveSystem(15-13)12341234Salivary glands(mucin) tolubricateTongue forchemoreception28Foregut-Conducting, Storage, Digestion-Esophagus and StomachCrop in some for storage/regurgitationStomach- begins digestion (e.g., pepsin)- food storage- mechanical mixing (muscular walls)- Monogastric (1 chamber, carnivores and omnivores)- Digastric (> 1 chamber)e.g., Some birds use to grind with pebbles and sand29ForegutMonogastric Stomach- strong muscular sac/tube- sphincters at both ends- mucus from goblet cells of gastric pit- HCl from parietal cells of gastric gland- pepsinogen from chief cells of gastric gland(15-17)30ForegutDigastric Stomach- herbivores- anaerobic fermentation by symbiotic bacteria and protozoans(15-18)- regurgitation1234- digestive enzymes( Carbohydrates -> sugars and gases ) sugars, amino acids, short FAs into bloodDomestic cattle,1L/min gas!(methane and