Biology 1012: Lecture Outline for Chapter 42 - Animal Form and Function

Outline

1. Adaptations

• Trade offs in Form and Function
  

2. Body Structures

• Tissues
• Organs
• Organ Systems
  

3. Body Size

• Surface to Volume Ratios
• Metabolic Rates
  

4. Homeostasis

• Homeostatic Mechansisms
• Thermal Regulation
  

Review Questions:

Which of the following groups includes all the others?

1. Protostomes
2. Acoelomates
3. Coelomates
4. Triploblastic animals
5. Arthropods
   

While on vacation in South Dakota, you decide to spend some time fossil hunting, hoping to find something that will completely revolutionize our understanding of animal phylogeny. Which of the following sets of characteristics would be considered most revolutionary?

1. A bilateral deuterostome
2. A radially symmetrical protostome
3. An asymmetrical animal with no tissues
4. A coelomate monkey
5. A pseudocoelomate animal that is a protostome.

I.  Animal Adaptations

     Modifications to better survive and reproduce

     Trade offs

• must balance costs with benefits

• the playing card analogy

   Allocate 21 points with one card of each suit.

• Lizard Experiments

Trade offs between egg quantity and egg quality.

• Hypothesis 1: females can produce either many small eggs or few large one.
  
• Hypothesis 2: Offspring quality (survival) increases with egg size.
  
• So, what’s the best strategy, many small eggs or few large ones?
  

Adaptation vs. Acclimatization

• Adaptation: Long Term

• Acclimatization: Short Term

 

II.  Building Blocks

• Animal Tissue Types
  
  • Epithelial

 

 

• Connective




• Muscle

 

 

 

• Nervous

What types of tissue are present in this arm?

Levels of Biological Organization

Atoms and Molecules
Cells
Tissues
Organs
Organ Systems
Organisms

The Importance of Size

Surface to Volume Ratios

Which has the higher surface to volume ratio?  a 1 sq. cm cube or a 5  sq. cm cube?

S/V ratio imposes limits

1. On cell size

2. On Transport Surfaces

High S/V – Use external surfaces

Low S/V - Use internal Surfaces

World’s Largest Cell

III.  Metabolic rates

Minimal rates - support basic life functions

Maximal rates - peak activity

In between rates influenced by many factors:

Question:

How does an animal’s metabolic rate affect oxygen consumption?

1. Metabolism has no impact on oxygen consumption.
2. Higher metabolic rates result in higher oxygen consumption
3. Higher metabolic rates result in lower oxygen consumption
4. Metabolic rates only affect oxygen consumption when an animal goes into anaerobic respiration.
5. Higher metabolic rates cause higher oxygen use in terrestrial animals, but not in aquatic animals.
   

Burning Calories

Basal Metabolic Rates (BMR)

Endotherms (“warm-blooded”) - generate body heat metabolically.

Human males = 1600-1800 kcal/day

Human females = 1300-1500 kcal/day

What about Ectotherms (“cold-blooded”) animals?

Endotherm vs Ectotherm Metabolic Rates

Body Size and Metabolic Rate

For Endotherms:

Smaller species - higher metabolic rates

Body Size and Metabolic Rate

Growth and Metabolic Rate
As an animal grows, its mass-specific metabolic rate (rate per unit mass) declines.
Otherwise not enough surface area to keep up with metabolic demands

Larval fish can breathe both through their skin and their gills. Which predominates?

Adaptations to Increase Surface Area

Consider the small intestine

IV. Homeostasis

Control Mechanisms

Negative Feedback

Animals have set points for:

Temperature
Blood pH
Blood oxygen
Blood Glucose

 

Temperature Regulation

Methods of Heat Exchange

Thermoregulation in Humans

Hypothalmus

Temps above or below 36.1 - 37.8 oC

Cooling Mechanisms

vasodilation
sweating

Warming Mechanisms

vasoconstriction
shivering

Ectotherms vs Endotherms

Heterotherms vs Homeotherms

Thermoregulation - Physiological and Behavioral Adjustments

Physiological

Control Rate of Heat Exchange

Vasodilation
Vasoconstriction
Countercurrent Heat Exchangers
Arterial Blood warms returning Venous Blood

Insulation

Fat
Fur
Feathers

Evaporative heat loss

sweating
Panting

Metabolic heat production

Shivering
Non-shivering Thermogenesis

Behavioral responses

Into or out of sun

Torpor

Bergmann's Rule (1847)

Body size of the individuals is usually greater in colder climates.

Allen’s Rule (1877)

species adapted to cold climates have smaller and shorter limbs and protruding body parts