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Marine Mammal Biology > Anatomy And Physiology > Flashcards

Anatomy And Physiology Flashcards

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0
Q

Key Features Influenced by an Aquatic Lifestyle:

A
  1. locomotion
  2. thermoregulation

3. diving
4. osmoregulation

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1
Q

The marine environment:

A
  1. density - 800 times greater than air
    - viscosity - 60 times greater than in air
  2. pressure
  3. thermal conductivity - 24 times greater than in air 4. light attenuation
  4. high salinity/absence of freshwater
    - changes in kidney
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2
Q

DRAG REDUCTION

A
  1. frictional/viscous drag

2. pressure drag
3. induced drag
4. wave drag

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3
Q

Frictional/Viscous Drag

A

• frictional drag of skin on water
• related to SA:V ratio (beneficial to have a low ratio)
• smooth skin - smooth boundary with fluid environment (see this in fully aquatic marine mammals)
• high turnover rate of outermost epidermal cells (some - once every 2 hours!)

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4
Q

Pressure Drag

A

• results from distribution of pressure around the body • dominating drag forces when swimming submerged
• fusiform shape - modification to reduce pressure drag

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5
Q

Induced Drag

A

• associated with water flow around flippers, fins, and flukes • act as hydrofoils - but formation of vortices around tips

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6
Q

Wave Drag

A

• occurs at surface ! bodies produce waves
• energy to move forward is minimized by wave
production
• total body drag - 4-5 times higher at surface
• negligible once animal is 3 body diameters below surface

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7
Q

BUOYANCY CONTROL

A
  1. increase quantity of materials that are less dense than water: air filled lung space (e.g. sea otter and manatee), fat/blubber
  2. reduce quantity of heavy materials - bone (density)
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8
Q

MOVEMENTS AND COSTS OF SWIMMING
Examples: otariids, phocids, cetaceans

A

• must produce propulsive forces equal to or greater than drag forces
• adaptations: enlarged propulsive structures + strong musculature, appendages
used as hydrofoils to produce thrust
• lack of recovery period during stroke cycle (unlike

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9
Q

Total Cost of Transport - COTTOT
- semi-aquatic mammals

- fully aquatic mammals

A

amount of energy required to move one unit of body mass a specific distance
- semi-aquatic mammals - 2-5 times higher than fully aquatic
- fully aquatic mammals - have similar values (and similar to terrestrial)

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10
Q

Thrust Production
• California sea lion
• cetaceans

A

• transmitting force from one place in body to
another!lever (i.e. a rigid structure that transmits force by rotating at a pivot point)
• California sea lion – muscles acting on brachium have large force-generating capacity + lever arm out is reduced
• cetaceans – axial muscles have large force- generating capacity + elongated neural spines + elongated transverse processes

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11
Q

Propulsive Efficiency
• ratio of span to chord
• high aspect ratio
• sea lion flipper
• sea otter feet
• cetacean flukes

A

• limb design that promotes efficiency is
one with long wingspan (length of wing from tip to base) and a short

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12
Q

maxilla
• manatee
• cetaceans

A

• floor of nasal canal and roof of
oral cavity
• manatee – most of maxilla lies
behind the orbit
• cetaceans – extensively
remodeled (

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13
Q

nasal cavity

A

• dorsal and central in skull

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14
Q

zygomatic arch
• cetaceans
• sirenians

A

• site of origin for masseter muscles
• cetaceans – reduced, especially in odontocetes
• sirenians – massive but porous, oil-filled (increases SA of attachment for the masseter)

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15
Q

occipital bone
• cetaceans

A

• articulates with the first cervical verterbra
(i.e. the atlas)
• spinal cord exits braincase through the occipital bone
• cetaceans – space in braincase between occipital bones and frontal bones is greatly reduced

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16
Q

III. THERMOREGULATION

A
  1. small SA:V ratio
  2. increased metabolic rate - activity and processing of food
    - most have similar basal metabolic rates to terrestrial mammals
    - however, will eat more and move around more when temps are low; still widely debated (proven in sea otters and neonates)
  3. insulation
  4. counter-current heat exchanger
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17
Q

Insulation

A
  1. Hair

2. Blubber

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18
Q
  1. Hair
A

• traps air ! but gets compressed when wet and diving
• length and density – sea otter = 130,000 hairs/cm2 and fur seals = 60,000 hairs/cm2
• thick, primary hair surrounded by multiple underhairs (~ 1-10; sea otters = 50-100!)
• sebaceous glands – paired and associated with each hair; skin

19
Q

Blubber

A

• thickened, adipose-rich hypodermis; energy store;
acts as a

20
Q

must be able to dump excess heat

A

• thermal windows - areas with less fur and
less blubber
• blubber - highly vascularized!can vasoconstrict or vasodilate (depending on ambient temperature)
• … counter-current heat exchanger

21
Q

Counter-Current Heat Exchanger

A

• arteries - move blood from heart (oxygen rich) to extremities; veins - move blood from extremities (oxygen poor) to heart
• lie on top of each other in extremities ! heat transferred from warm arterial blood to cool venous blood (cooled by external environment)
• so, when it

22
Q

DIVING

A

A. Lung adaptations
B. Oxygen Stores/Consumption
C. Diving Physiology

23
Q

Lung adaptations

A

• size - lung size (relative to body size) – not
significantly increased
• pressure – V of a given mass is inversely proportional to the pressure it is experiencing ! collapse (lungs and trachea) at depth (flexible rib cage and cartilage-enforced airways)
• nitrogen narcosis and the bends – avoidance (by forcing air into non-gas exchanging regions of lungs)
• female elephant seals – potential use as narcotic

24
Q

Oxygen Stores/Consumption

A

• hypoxia!hypercapnia!accumulate by-products of anaerobic metabolism =

25
Q

Diving Physiology

A
  1. breath holding - apnea
  2. bradycardia - reduction in heart rate
  3. peripheral vasoconstriction/selective ischemia - selective redistribution of blood
  4. diving hypometabolism
26
Q
  1. Breath holding
A
  • increased by ability to store oxygen in lungs, blood, and muscles
  • not correlated to size overall but is correlated to size within groups (phocids, otariids, odontocetes, mysticetes)
27
Q
  1. Bradycardia
A
  • rapid, profound decrease in heart rate with submergence - maintained throughout dive, followed by tachycardia
  • e.g. killer whale - 60 beats/min ! 30 beats/min (15+ sec); California sea lion - 150-250 beats/min!20-50 beats/min (1-3 mins)
  • inverse relationship between heart rate and length of dive - e.g. grey seals - 119 beats/min ! 4 beats/min for dives
    exceeding 15 mins
  • does not require diving – e.g. ringed seals resting underwater at breathing hole
28
Q

Vasoconstriction/Selective Ischemia

A

• selective redistribution of blood to brain and heart
• marine mammal hearts – specialized to maintain blood pressure despite decline in heart rate (aortic bulb)
• explains, in part, how O2 is conserved during diving asphyxia
• sampling O2 in muscle myoglobin and blood hemoglobin!indicates circulatory isolation
• side-effect of moving blood away from locomotor muscles!build up of lactate (post-dive recovery period)
• adaptations: myoglobin, elevated mitrochondrial volume and density in these muscles, and altered aerobic enzyme capacities
• seal kidneys and liver experience ischemia ! incredible tolerance

29
Q

Hypometabolism

A

• O2 available ≠ O2 required to sustain metabolic rates
• partially due to selective ischemia and reduced metabolism in non-
perfused organs
• episodic decline in metabolic rate !

30
Q

Exercising Underwater:

A

• typically heart rate increases as function of exercise intensity
• doesn

31
Q

VI. CARDIOVASCULAR SYSTEM

A

marine mammal CVS – 1. must deliver O2 selectively during breath holding and 2. must regulate the T of reproductive system
! relates to: a. arterial supply to brain b. AVAs
c. thermoregulation of reproductive structures

32
Q

Arterial Supply to the Brain

A

• typical brain receives blood via internal carotid and vertebral arteries!enter cranial cavity and anastomose (

33
Q

Arteriovenous Anastomoses (AVAs)

A

• vascular channels that connect an artery to a vein, near a capillary bed
• arterial blood that flows through an AVA bypasses capillaries and is rerouted
back toward heart before getting to terminal site
• associated with proximal vessels ! shunt arterial blood away from extremities
• e.g. flukes of a bndf – have AVA that are 2 mm in diameter!
• e.g. Weddell seals – said to play important role in selective ischemia
• also play a role in thermoregulation ! lie near surface of skin and if dilated can effectively transfer heat to environment

34
Q

Thermoregulation - Reproductive System

A

• special thermoregulatory requirements of the reproductive system
• viable sperm production and storage – separation from body core (e.g. scrotum – otariids and polar bears)
• walrus and phocids – testes between blubber and abdominal muscles; cetaceans – deep in abdominal cavity
• phocids = testes enveloped in venous network that receives blood from surface (i.e. flipper)
• odontocetes – countercurrent heat exchanger!arterial and venous plexus (veins drain from dorsal fin and flukes)
• may relate to fetal temperatures as well

35
Q

NERVOUS SYSTEM

A

• functions to detect changes in both internal and external environments of the animal
• CNS = central nervous system + PNS = peripheral nervous system CNS – brain and spinal cord
PNS – all other nervous tissues in body
• PNS - specialized neurons (receptors) transduce mechanical, thermal, chemical and electromagnetic signals into nervous signals!transmitted to CNS through sensory (afferent) nerves
• interneurons in CNS use incoming sensory info ! coordinate rapid and appropriate responses via signals sent through motor nerves (efferent) to effector organ
• LOOP

36
Q

a. Cranial Nerves

A

• 12 pairs of cranial nerves connect the PNS with the brain – 3 sensory (I, II, and
VIII), 4 motor (III, IV, VI, XII) and 5 mixed (V, VII, IX, X, XI), and 13th (0 = closely
associated with olfactory nerve, I)
• size of nerve depicts higher conduction capacity and info transmission
I – olfactory and II – optic
! reduced in most
! increased in polar bears
VIII - vestibulocochlear nerve
! high-speed communication with brain
! odontocetes – 3-4 times more and largest axon diameters (conduction velocity)
V – trigeminal nerve
! mysticetes - largest cranial nerve ! pinnipeds – very large (vibrissae) ! manatees – massive (tactile mouths and vibrissae)
VII – facial nerve
!odontocetes – large (echolocation)

37
Q

Neural Regulation of Diving Responses

A
38
Q

RESPIRATORY SYSTEM

A

• air enters through nostrils and mouth ! pharynx
• from pharynx ! esophagus (food) or larynx (air)
• from larynx!trachea!bronchi (primary and secondary)!lobes of lungs

39
Q

Isolation of Respiratory System from Aquatic Environment

• sea lions
• cetaceans

A

• larynx - protects respiratory system from food and fluids
• marine mammals must protect their respiratory system from water in their
environment
• sea lions - resting position of nares = closed
• cetaceans - nasal plugs seal entrance to nasal cavity when resting
• cetaceans - trachea and esophagus are morphologically separated by goosebeak!can eat and swim/breathe at the same time; no gag reflex
•

40
Q

DIGESTIVE SYSTEM

A
  1. capture and manipulation of food – wide variety of feeding mechanisms and prey
  2. mechanical and chemical digestion
  3. nutrition
    • mouth (ingestion)!processed (mastication)!swallowed!into pharynx! esophagus!stomach!small intestine!large intestine!gut & eliminated as feces
41
Q

Stomach/Mechanical & Chemical Digestion:
pinnipeds

odontocetes
mysticetes
cetaceans
Intestines

A

DIGESTIVE SYSTEM
1. capture and manipulation of food – wide variety of feeding mechanisms and prey 2. mechanical and chemical digestion
3. nutrition
• mouth (ingestion)!processed (pinnipeds – single, highly distensible odontocetes – compartmentalized; forestomach
is highly distensible pouch of the esophagus
mysticetes – non-glandular forestomach with multiple compartments
!all cetaceans lack gall bladder sirenians – single, glandular stomach
Intestines – pinnipeds (long for carnivores), cetaceans (vary), and sirenians (very long!)

42
Q

REPRODUCTIVE SYSTEM
Male Reproductive Structures

A

• form and function similar to terrestrial mammals
• testis-to-body-size ratio – varies but related to mating strategy (e.g. dusky dolphins = 8%, right whales = 2000 lbs)
• penis retracted into body wall (pinnipeds – vascular with baculum, sirenians – vascular w/o baculum, cetaceans – fibroelastic)

43
Q

REPRODUCTIVE SYSTEM
Female Reproductive Structures:

A

• bicornuate uterus common to terrestrial mammals • ovaries paired and similar in structure, location and
shape
• placental type (varies – ancestral) – cetaceans = diffuse, sirenians – zonal, pinnipeds, polar bears and sea otters = zonal

44
Q

OSMOREGULATION

A

Balance between water intake and excretion - maintenance of amount and electrolyte concentration of fluids in body
- eating and drinking balanced by removal of excess fluids and electrolytes (urine, feces, and evaporation)
- kidney - of marine mammals adapted to high salinity of seawater (and absence of freshwater)

45
Q

Marine mammal kidney:

A

• larger
• 2 kidneys with multiple reniculi
• # of reniculi relates to level of marine exposure and diet
• cetaceans (450 reniculi), mysticetes (3000), otters and manatees (6-8)
• production of highly concentrated urine
• approx. 1/5 of cardiac output flows through kidney

46
Q

Acquiring Water

A
  1. drinking freshwater
  2. via preformed and metabolic water in food
    - fish and invertebrates ~ 60-80% water
    - metabolic water derived from metabolism of food (fat, protein, and carbohydrates)
    - fasting conditions (catabolize fat reserves, decrease urinary output, general minimization or lack of sweat glands)
  3. mariposia - drinking saltwater - sea otters - highest
    - documented in other species: northern fur seal = 300 ml/day, in cetaceans occurs during fasting but still low (800 ml/day in common dolphin), other values - incidental??

Marine Mammal Biology (4 decks)

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