lectures 23, 20 nov 2003 chapter 15, feeding and digestion vertebrate physiology ecol 437 university...
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Lectures 23, 20 Nov 2003Chapter 15, Feeding and Digestion
Vertebrate PhysiologyECOL 437
University of ArizonaFall 2003
instr: Kevin Boninet.a.: Bret Pasch
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Vertebrate Physiology 437
1. Feeding and Digestion (CH15)
2. Announcements… -Exams returned next week -Powerpoint preview -Eldon Braun Thanks
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FEEDING
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Feeding
Filter Feeding -baleen whales -flamingoes -planktivorous fish with modified gill rakers -amphibian larvae
Fluid Feeding -lampreys -vampire bats (analgesic and anticoagulants)
(15-3)
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-Jaws, teeth, beaks-Form and function matched
Seizing with mouth etc.
Modification for diet(15-7)
Eryx tataricus
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(15-8)
Modification for diet
Seizing with mouth etc.
-Form and function matched
-Darwin’s Finches in Galapagos
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Seizing with mouth etc.
Most toothed non-mammalian vertebrates have homodont dentition
-Exception: Some snakes
Viperidae, including
rattlesnakes
(15-6)
Some snakes also with venom
- hemolytic, neurotoxic
Eunectes murinus7
Heloderma Front FangedHypodermicDuvernoy’s/Venom Gland
Solenoglyph
Proteroglyph Elapidae
ViperidaePough et al. 2001
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Joe SlowinskiMyanmar, BurmaBungarus multicinctusMultibanded Kraitalpha bungarotoxin
nicotinic ACh receptor antagonist
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… Alethinophidia, Macrostomata, Caenophidia, Colubroidea
Elapidae(62 genera, 300 species)
- Cobras, coral, and sea snakes
- venomous- proteroglyph dentition
maxilla 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 sympatrics
Micruroides euryxanthus
Naja spp.
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Pit Organsmultiple origins - vipers, boas,
pythons
infrared image
Pough et al. 2001(pit sensitivity to 0.003 C)
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Gastric Brooding Frog Etc.
Python regius
Rheobatrachus vitellinus
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Pough et al. 2001
UnidirectionalSuction Feeding
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Suction Feeding
Salamanders
1. Jaws open2. Hyoid apparatus (floor of mouth) drops3. Muscles keep gills closed
A few genera asymmetrical- flexible mandible (cartilage)
Figure 9-5Pough et al. 2001
Cryptobranchus alleganiensis
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Suction Feeding
Anurans
Tadpolesunidirectionalspiracle(s)
filter feeders - strain
- mucus
Figure 9-6fPough et al. 2001
buccal pharyngeal
atrial
branchialfilters
Stebbins and Cohen, 1995
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Turtle Suction Feeding
Bidirectional, no teeth (keratinous beak)
1. Compensatory suction - displaced water
2. Inertial suction - modified hyobranchial - greater expansion
Esophogeal modifications - prevent prey escape - Dermochelys, 5 cm spines
Figure 9-13Pough et al. 2001
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Feeding
Chamaeleo jacksonii
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Projectile Feeding
Salamanders
Hydromantes
Deban et al. 1997
a
b
cd
retractor
protractor
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Scolecophidians
Snake Feeding
Ancestral Group
- small gape
- short jaws
- many small prey
Leptotyphlops (teeth lower only)
Mandibular raking
Fig. 4-25Pough et al. 2001
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Cranial Kinesis
Snake Feeding
Unilateral Feeding
- two sides of lower jaw (dentary) unfused
- intramandibular hinge
Fig. 9-33Pough et al. 2001
- looser streptostylic quadrate
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Fig. 9-25Pough et al. 2001
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~Terrestrial Feeding
Turtles -beak shape thickness (durophagic) motion (Gopherus)
Geocheloneelephantopus
Alligator Snapping TurtleMacroclemys temminckii
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Pough et al. 2001
Egg Eating (e.g., Dasypeltis)elastic neck skin, few teeth, vent. vertebral processes
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Digestive Systems
Three 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 reactor
Often 2,3 combined (e.g., stomach and small intestine)
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-Food quality-Body Size-Temperature (ectotherms)
Digestive Systems
Transit time (time to digest), cost, and anatomy variable:
(15-11)
(15-12)
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Generalized Digestive System
(15-13)
1
2
3
4
1
2
3
4
Salivary glands (mucin) to lubricate
Tongue for chemoreception
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(15-16)
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Generalized Digestive System
(15-13)
1
2
3
4
1
2
3
4
Salivary glands (mucin) to lubricate
Tongue for chemoreception
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Foregut
-Conducting, Storage, Digestion-Esophagus and Stomach
Crop in some for storage/regurgitation
Stomach
- 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 sand
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ForegutMonogastric 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)
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Foregut Digastric Stomach
- herbivores
- anaerobic fermentation by symbiotic bacteria and protozoans
(15-18)
- regurgitation
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3
4- digestive enzymes
( Carbohydrates -> sugars and gases ) sugars, amino acids, short FAs into blood
Domestic cattle, 1L/min gas! (methane and CO2)
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END
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