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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FEEDING3

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, ColubroideaElapidae

(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

c d

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

12

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

12

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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