Lectures 23, 20 Nov 2003 Chapter 15, Feeding and Digestion Vertebrate Physiology ECOL 437

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

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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

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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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