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Vertebrate Zoology

SCBI 305

Circulatory and Digestive Systems

Circulatory System• หน้าที่

– ลําเลียง อาหาร O2, CO2, ฮอร์โมน เม็ดเลือด ไปสู่เซลล์ต่างๆใน

ร่างกาย

– รักษาสภาพอุณหภูมิร่างกาย pH

• Closed system

ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy, Function, Evolution (5th ed.).

McGraw-Hill, Inc., New York.

Blood passes once through heart Blood passes through heart twice

ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy, Function, Evolution (5th ed.).

McGraw-Hill, Inc., New York.

Oxygenated blood

Why are fish hearts small?

ที่มา: Helfman et al. 1997. The Diversity

of Fishes. Blackwell Science.

2

ที่มา: Kardong, KV. 2009. Vertebrates:

Comparative Anatomy, Function,

Evolution (5th ed.). McGraw-Hill, Inc.,

New York.

Bidirectional circulation

Vessels of the circulatory system• Vein

– Blood into heart

• Major veins

– Common cardinal (sinus)

in primitive vertebrates

– Portal system (hepatic

portal veins, renal portal

veins)

– Post-, pre- cava (vena

cava)

• Aorta

– Blood out of heart

• Dorsal, ventral aortae

• Arteries

• Aortic arches

ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy, Function, Evolution (5th ed.). McGraw-Hill, Inc., New York.

Phylogenetic modification

• Correlated with functional changes

Water

Gill respiration

Land

Lung respiration

Pulmonary circulation

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Aortic arches

• Primitive pattern of aortic arches: debatable

• 6 = # taken as the basic embryonic pattern

ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy, Function, Evolution (5th ed.). McGraw-Hill, Inc., New York.

• Fishes

Gills

Ventral aorta

Aortic arches

Capillaries

Gills

Capillaries Aortic arches Dorsal aorta Body

Afferent artery

Efferent artery

1st arch absent

in adult of

most fishes

• Sharks, chondricthyans + primitive ray finned fishes

Modified into small

spiracle (sensory organ)

Lobe finned fish (Sarcopterygii)

Fishes with supplementary air-breathing organ

Lung highly vascularized

Little mixing between oxygenated & deoxygenated blood

(undivided heart)

4

• Amphibians

Larva: arch I, II absent

III, IV, V external gills

VI lung

adult salamander: lost of

external gills

Adult frog: arch III, IV, VI persist

• Reptiles

• Modification of arch IV—systemic arches (double arches)

unite behind the heart to form common dorsal aorta

• Subdivision of ventral aorta

• Arch IV (pulmonary arch) branching out to lung

• Birds

Pre-dominate systemic

arch (left systemic arch not

fully developed)

Wing vessels (subclavians)

Present in turtles & birds

serving as major anterior

vessels in many birds

• Mammals

Only 3 arches (III, IV, VI) present in adult mammals

Carotid arterySystemic arch (left predominates)

Pulmonary arch

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Double systemic arches in

amphibians & reptiles

Single systemic arch (right)

in birds (left) in mammals

Most similar to basic pattern

Aortic arches

Systemic arches

Pulmonary arch

Arterial circuits

Venous vessels • 2 systems in double circulation (Not in fishes)

– Pulmonary systems lung (found in fishes with

lungs, air-breathing vertebrates)

– Systemic systems hepatic portal veins, renal

portal veins, other veins (few differences among

vertebrates, tending to retain basic characters)

• Abdominal veins present in fishes, merged/

absent in tetrapods

Hearts • Original form contractile vessel

– In amphioxus

• Fishes: 4 chamber heart

– Atrium

– Ventricle

– Conus arteriosus found in many fishes, absent in adult

tetrapod

– Bulbus arteriosus (lacking cardiac muscle & conal valves)

found in most teleosts

• Primitive heart (hagfish)

ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy, Function, Evolution (5th ed.). McGraw-Hill, Inc., New York.

6

• Lamprey—4 chamber heart

ที่มา: Kardong, KV. 2009. Vertebrates:

Comparative Anatomy, Function, Evolution (5th

ed.). McGraw-Hill, Inc., New York.

Collect deoxygenated blood containing

pacemaker

Thick wall

Chondrichthyes:

4 chambers

Sinus venosus

Atrium

Ventricle

Conus arteriosus

Gills

Body

Ventral aorta

ที่มา: Helfman et al. 1997. The Diversity

of Fishes. Blackwell Science.

Sinus venosus

Atrium

Ventricle

Bulbus arteriosus

Gills

Body

Ventral aorta

Conus arteriosus—muscular

extension of ventricle

Teleosts:

2 chambers

ที่มา: Helfman et al. 1997. The Diversity

of Fishes. Blackwell Science.

Small—not chamber-like

Small—not chamber-like

Formation of spiral valve in

the conus arteriosus for

regulating blood flow into

left/ right pulmonary arches

ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy, Function, Evolution (5th ed.). McGraw-Hill, Inc., New York.

7

• Frog heart: 3 chambers

– 2 atria, 1 ventricle

Body

Right atrium

Lungs/ skin

Ventricle

Left atrium

Ventricle

Body

ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy, Function, Evolution (5th ed.). McGraw-Hill, Inc., New York.

Close similarity

between lungfish &

amphibians

• Mixed blood in amphibian heart

• Why do their hearts evolve in this direction?

• Amniote heart: 4 major chambers

– 2 atria

– 2 ventricles

• Reptiles (lizards)

– 5 chambered heart (2 atria, 3 compartments of ventricle)

ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy, Function, Evolution (5th ed.). McGraw-Hill, Inc., New York.

Reduced sinus venosus but same functions Completely divided atrium

Ventricle with 3 compartments

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• Reptile (alligator)

ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy,

Function, Evolution (5th ed.). McGraw-Hill, Inc., New York.

Completely divided ventricle • Cardiac shunt permitting heart to produce

different pressures within systemic & pulmonary

circuits

• Useful

• Bird

ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy,

Function, Evolution (5th ed.). McGraw-Hill, Inc., New York.

4 chambered heart

Reduced sinus venosus

Conus arteriosus

pulmonary & aortic trunks

• Mammal

ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy,

Function, Evolution (5th ed.). McGraw-Hill, Inc., New York.

4 chambered heart

Reduced sinus venosus

( Purkinje fiber =

pacemaker) in wall of

right atrium

Conus arteriosus

pulmonary & aortic

trunks

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• Birds & mammals 4 chambered heart BUT

independent evolution

– Seen in embryonic development

Pulmonary circuit Systemic circuit

• Adaptation to environment ≠ improvement of

design

• Incompletely divided heart ≠ imperfect

– Perfectly matching with environment

• Evolution ≠ progressive improvement

– Alternative way of adaptation to demands of

different lifestyles

Heat transfer• Another function of the circulatory system

• Reptiles basking in the sun absorb heat in their

peripheral blood vessels to warm tissues

• Body heat dissipates to surface of body via capillaries

• Endothermic vs. ectothermic

• Homeothermic vs. poikilothermic Animals that show a change in

body temperatureAnimals that maintain constant

body temperature

• Birds & mammals body temperature

regulations using own metabolism

• Other vertebrates body temperature

depending on environments

– Adaptation behaviors (movements)

• Effects of climate change

• Tolerant ranges, limitations geographic

distribution

• Adaptations to climate change?

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ที่มา: Araujo et al. 2013. Ecology Letters 16: 1206-1219.

Lower end Upper end

Limiting factor for

distribution in cold

environments

Temperature

Cold temperature Hot temperature135 species26 species

Limiting factor for

distribution in warm

environments

Natural selection physiological responses to

lower temperature

• Phylogenetic similarity

– Similar responses to temperatures in closely related

species

• Higher temperature narrower cold temperature

tolerance, NOT increasing hot temperature

tolerance

Species cannot survive

กิน

• Eat = put food in mouth, swallow & chew it

• Consume =

• Ingest = take food into body usually by swallowing

• Digest = be changed after eating into a form that the body can use

• Absorb = take in a substance from the surface

• Egest = discharge undigested food as forces

– ≠excretion

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โครงสร้างระบบทางเดินอาหาร

• Buccal cavity: palate, teeth, tongue, oral glands

• Pharynx

• Esophagus

• Stomach

• Intestines: small, large

• Others

Buccal cavity

• Palate = roof of the buccal cavity

– Fusion of ventral skull bones

• Teeth = derivations of dermal armor

– Toothless vertebrates agnathans, sturgeons, some

toads, turtles, birds, baleen whales

– Toothed vertebrates fishes (highly variables), most

amphibians, some reptiles, some birds, mammals

• Teeth in fishes

– Buccal cavity, pharynx

• Tetrapods

– Palate, vomer, palatine, pterygoid bones

• Crocodiles, birds, mammals

– Jaws

• Reduction in numbers and distribution (evolution)

• Succession of teeth

• Tooth replacement in waves (back to front, every other

tooth)

• Mammals 2 sets of teeth

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• Shape of teeth similar in vertebrates except

mammals

• Mammalian teeth incisors, canines, premolars,

molars (heterodont dentition)

• Tongue

• Primary tongue (crescent-shaped elevation in the floor of the buccal cavity caused by the underlying hyoid skeleton)

– Found in most fishes, primitive amphibians

• Primary tongue + glandular field

– Found in most amphibians

• Primary tongue + glandular field + lateral lingual swelling

– Found in reptiles & mammals

• Tongue mobility

– Immobilized turtles, crocs, some birds, whales

– Highly mobile snakes, insectivorous lizards & amphibians

& birds

– Attached to floor of buccal cavity but some mobility

mammals

• Functions: Capturing, gathering food (woodpeckers), Taste,

Swallowing, Grooming, Thermoregulation (dogs), Human

speech

• Oral gland

• Saliva

– Not found in fishes

• Venom (lizards, snakes, mammals)

• Anticoagulant (vampire bats)

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Pharynx • Fish respiratory organ

• Tetrapods foregut

Esophagus

• Muscular tube connecting pharynx and stomach

• Crop (birds)

Stomach • Muscular chamber

• Storage & macerating & secreting digestive enzymes

• Weakly developed in cyclostomes

Diversity of digestive tracts in fishes

Straight tube

ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy, Function, Evolution (5th ed.). McGraw-Hill, Inc., New York.

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• Differentiated from the esophagus in amphibians,

reptiles

• Glandular stomach + muscular stomach (gizzard) in

birds

• Well-developed in mammals

– Multi-chambered stomach

Intestine

• Variation in fishes

Spiral value—modification

of intestine in

chondrichthyans,

sturgeons, lungfishes,

bichirs, coelacanths,

bowfin, gars—increases

absorptive surface areas ที่มา: Helfman et al. 1997. The Diversity of

Fishes. Blackwell Science.

• Amphibians coiled small intestine, short & straight

large intestine

• Reptiles & birds coiled small intestine, short large

intestine emptying to the cloaca

• Mammals coiled, differentiated, long small intestine,

long large intestine

Others • Liver

• Gall bladder

– Cyclostomes, most birds, some mammals have no gall

bladder

• Pancreas

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• Ceca

– Pyloric & duodenal ceca common in teleosts (for digestion

& absorption)

– Herbivorous Tetrapods (cellulose digestion)

ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy, Function, Evolution (5th ed.). McGraw-Hill, Inc., New York.

• Cloaca

– End of digestive tract (collection of intestine, urinary,

genital ducts) open to outside

– Opening to outside through a cloacal opening/ vent

– Latin: cloaca = sewer

– Found in all vertebrates during embryonic development

– Shallow or none in lampreys, ray-finned fishes, mammals

(except monotremes)

– Anus (end of digestive tract if no cloaca present)

• Well-developed in sharks & lungfishes

• Remain in amphibians, reptiles, birds, monotremes

• Lost in chimaera, ray-finned fishes, coelacanth,

eutherian mammals

– Anus

Cloaca

Remain

well-developed, subdivided,

incorporated into other structures

Lost

Diet change

• Seasonal variation

– Opportunistic feeders

– Generalists

– Specialists

• Ontogenetic niche shift

– Evolutionary adapatation

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Ontogenetic niche shift• Irreversible, genetically determined

• Morphological changes, age

– Habitat change?

• Driving forces (Claessen & Dieckmann 2002—Evolutionary

Ecology Research vol. 4: 189-217)

– Predator avoidance

– Niche variation