1. osmoregulation (brief wrap up) 2. feeding and digestion...
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Lecture 27, 22 November 2005Finish Osmoregulation (Chapters 25-28)
Feeding and Digestion (Chapter 4)
Vertebrate PhysiologyECOL 437 (aka MCB 437, VetSci 437)
University of ArizonaFall 2005
instr: Kevin Boninet.a.: Kristen Potter
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1. Osmoregulation (brief wrap up)2. Feeding and Digestion
Text:Chapter 4(skim 5-7, read 8+9)
-Exams Graded (retrieve in my office Wed 11am, or after Thanksgiving)-Seminar Write-Ups (29 Nov)-Term Paper (01 Dec)-Oral Presentations last week of class
(PPT files to KEB one day before)(most on 07 Dec, four on 06 Dec in lecture)
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Salt Secretion:
(Eckert 14-14)
active
Down electrochemical gradient(Paracellular)
recycle
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Salt Glands
Shark rectal glands to dispose of excess NaCl-blood hyperosmotic to seawater, but less salt-more urea and TMAO (trimethylamine oxide) -NaCl actively secreted
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Shark Rectal Salt Glands
Salt-secreting cells:-Na/K-ATPase pump in basolateral
membrane-generates gradient for Na+ by which
Na+/2Cl-/K+ cotransporter drivesup [Cl-] in cell
-Cl- across apical membrane-Na+ follows paracellularly down
electrochemical gradient (and H2O)
-apical membrane impermeable to ureaand TMAO
-therefore iso-osmotic secretion withlots of NaCl
(Eckert 14-36)
… slightly different in birds and lizards
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Salt Glands
Nasal/orbital salt glands of birds and reptiles-especially species in desert or marine environments.
Hypertonic NaCl secretions (2-3x plasma osmolarity)
Allows some birds to drink salt water and end up with osmotically free water
Amblyrhynchus cristatus
(Eckert 14-36)
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Fish Gills Chloride cells involved in osmoregulation-(recall Pelis et al. paper on smolting)-lots of mitochondria to power ATPases-mechanism similar in nasal glands (birdsand reptiles), and shark rectal gland
(Eckert 14-14)
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8Hill et al. 2004, Fig 26.7
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Freshwater fish:The mechanism basically reversed to allow uptake of salt from water against concentration gradient
proton pump to create electrical gradient
Na/K-ATPaseto generate Na gradient
(Eckert 14-31)
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Sea Freshwater
Switch between getting rid of excess salt in seawater and taking up salt in freshwater
Growth hormone and cortisol for sea(more active chloride cells with more
Na/K-ATPase activity)
(recall Pelis et al. paper on smolting)
Prolactin for freshwater
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FEEDING(Hill et al. Ch 4)
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Feeding
Chamaeleo jacksonii
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Feeding
Filter Feeding(Suspension Feeding)
-baleen whales-flamingoes-planktivorous fish with modified gill rakers-amphibian larvae
Fluid Feeding-lampreys-vampire bats(analgesic and anticoagulants) (Eckert 15-3)
14Hill et al. 2004, Fig 4.9
10% Rule
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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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17http://www.mun.ca/biology/scarr/Adaptation_in_Darwins_Finches.html
Darwin’s FinchesGalapagos Islands, Ecuador
18http://www.mun.ca/biology/scarr/Adaptation_in_Darwins_Finches.html
Darwin’s FinchesGalapagos Islands, Ecuador
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Seizing with mouth etc.
Most toothed non-mammalian vertebrates have homodontdentition
-Exception: Some snakes
Viperidae, including
rattlesnakes
(15-6)
Some snakes also with venom
- hemolytic, neurotoxic
Eunectes murinus7
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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 receptorantagonist
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11 Sept 2001
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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 9-5
Pough et al. 2001
Cryptobranchusalleganiensis
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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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Projectile Feeding
Salamanders
Hydromantes
Deban et al. 1997
a
b
cd
retractor
protractor
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Fig. 9-25Pough et al. 2001
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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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Herbivory- omnivores eat fruits and flowers- true herbivores with specializations:
symbionts and gut morphology- smaller indivs eat more nutritious parts
- Iguanas (need to acquire symbionts)no parental carecommunal nestinghatchlings
eat soiljuveniles
eat parental feces
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Ontogenetic Changes
Mammals?Lactase?
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- Amphibian Larvaemetamorphosingare most vulnerable
Pough et al. 2001Fig 15-16 2004
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Cannibalism
- rare in reptiles- widespread in amphibs - esp. larval stages- some with distinct cannibalistic morphs- often facultative
Ambystoma, Spea, Scaphiopus
- Benefitsenergyreduced competition
Scaphiopus couchii
- Costs eating a relative (kin recognition)acquire pathogens
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Pough et al. 2004