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