Ch.4 Comparative Vertebrate Anatomy

Vocabulary practice flashcards covering animal size and shape, scaling principles, surface area-to-volume dynamics, metabolic rate, and biological adaptations.

Scaling

The study of size and its consequences.

Haldane's Principle of Convenient Size

The concept articulated by J. B. S. Haldane in 1926 stating that for every type of animal there is a most convenient size, and a large change in size inevitably carries with it a change of form.

Biological demands

Requirements placed on an animal's body design related to living functions, including feeding, capturing prey, and protection from weather.

Physical demands

Mechanical and physical forces that influence an animal's body design, specifically movement and supporting weight against gravity.

Metabolism

The sum of all chemical reactions that occur in the body.

Chemical reaction

The formation of new chemical bonds or the breaking of old chemical bonds between atoms.

Metabolic rate

The overall rate at which metabolic reactions use energy.

Mass-specific metabolic rate scaling

The physiological relationship in which oxygen consumption per kilogram of body mass per hour ($\text{ml } O_2\text{ kg}^{-1}\text{h}^{-1}$) decreases as body mass increases, meaning smaller mammals consume oxygen at a much higher rate per unit mass than larger mammals.

Gravity

A natural phenomenon that brings all things with mass toward one another.

Surface tension

The tendency of a liquid's surface to resist rupture when placed under tension or stress.

Surface area scaling

A geometric scaling relationship where the surface area of an animal increases in proportion to the square of its linear dimensions ($\text{length}^2$).

Volume and mass scaling

A geometric scaling relationship where the volume and mass of an animal increase in proportion to the cube of its linear dimensions ($\text{length}^3$).

Surface area-to-volume ratio ($SA:\text{Vol}$)

The ratio comparing surface area to volume, which decreases as an organism grows larger because volume increases much faster than surface area.

Absorption

The passage of digested foods from the digestive tract into blood or lymph.

Assimilation

The movement of digested food molecules into the cells of the body where they are used.

Microvilli

Microscopic projections forming a brush border on absorptive epithelial cells that expand surface area to promote efficient exchange of materials and heat.

Gill lamellae

Thin, highly vascularized plate-like structures on fish gill filaments that maximize surface area for gas exchange between water and blood.

Pelycosaur limb scaling

The structural adaptation demonstrated by extinct mammal-like reptiles (e.g., Mycterosaurus, Varanops, and Ophiacodon retroversus), where larger species possess disproportionately massive, robust femurs to carry increased weight against gravity.

Isometry

Geometric similarity in which proportions remain constant with changes in size, as observed across different species within the salamander genus Desmognathus.

Allometry

The study of a change in size or shape of one part correlated with a change in size or shape of another part, as seen in the shifting bodily proportions during human growth from infant to adult.