Animal Form and Functions

• Animal body plans

  • Asymmetrical
  • Radial symmetry
  • Bilateral symmetry
• Asymmetrical


  No pattern or symmetry
• Radial symmetry

  Animal has an up-and-down orientation, any plane cut along its longitudinal axis produces equal halves
• Bilateral symmetry


  Animal has definite right and left sides
• Anterior


  Front
• Posterior


  Rear
• Dorsal


  Toward the back
• Ventral

  Toward the stomach
• Aquatic animals with bilateral symmetry


  • Tend to have a fusiform shape (tubular body tapered at both ends) to decrease drag
• Aquatic organisms are constrained in shape by the forces of drag in the water, while land-dwelling organisms are constrained mainly by gravity</b>
• Most adaptations in birds are for gravity, not for drag
• Maximum speed of assorted land and marine animals

  • Cheetah (113 km/h)
  • Quarter horse (77 km/h)
  • Fox (68 km/h)
  • Shortfin mako shark (50 km/h)
  • Domestic house cat (48 km/h)
  • Human (45 km/h)
  • Dolphin (32-40 km/h)
  • Mouse (13 km/h)
  • Snail (0.05 km/h)
• Exoskeleton


  Hard outer covering or shell that provides protection and attachment points for muscles
• Exoskeletons are often made of tough polymers like chitin and biomineralized with materials like calcium carbonate
• Ingrowths of the exoskeleton called apodemes function as attachment sites for muscles
• Animals with exoskeletons must shed or molt their original covering in order to grow
• Doubling of body size increases weight by a factor of eight, requiring significant increase in exoskeleton thickness
• This limits most animals with exoskeletons to a relatively small size
• Exoskeleton


  Tough and resistant outer cover of an arthropod, often constructed of chitin and biomineralized with materials like calcium carbonate, fused to the animal's epidermis
• Apodemes


  Ingrowths of the exoskeleton that function as attachment sites for muscles, similar to tendons in more advanced animals
• Molting


  Animal synthesizes a new exoskeleton underneath the old one, then sheds or molts the original covering
• Increasing thickness of the chitin necessary to support increased weight limits most animals with an exoskeleton to a relatively small size</b>
• Endoskeletons are more efficient than exoskeletons because muscles are attached on the outside, making it easier to compensate for increased mass
• Diffusion


  Process by which nutrients and wastes are exchanged between a cell and its watery environment
• Surface-to-volume ratio

  Ratio of the surface area to the volume of an object, which decreases as the size of the object increases, making diffusion less efficient
• Multicellular organisms solve the problem of diffusion limitations by having specialized cells and organ systems that efficiently transport nutrients and remove waste
• Endotherm


  Warm-blooded animal that can maintain a relatively constant body temperature
• Ectotherm


  Animal that relies on the environment to regulate its body temperature
• Basal metabolic rate (BMR)


  Metabolic rate at rest in endothermic animals
• Standard metabolic rate (SMR)


  Metabolic rate at rest in ectothermic animals
• Smaller endothermic animals

  Have a higher BMR per body weight than larger endothermic animals
• More active animals

  Have a higher BMR or SMR
• Torpor


  Decreased activity and metabolism that allows animals to survive adverse conditions, including hibernation and estivation
• Sagittal plane


  Divides the body into right and left portions
• Midsagittal plane


  Divides the body exactly in the middle, making two equal right and left halves
• Frontal (coronal) plane


  Separates the front from the back
• Transverse (horizontal) plane


  Divides the animal into upper and lower portions
• Dorsal cavity


  Contains the cranial and vertebral (spinal) cavities
• Ventral cavity

  Contains the thoracic cavity (with pleural and pericardial cavities) and the abdominopelvic cavity
• Physical anthropologists study the adaptation, variability, and evolution of human beings and their living and fossil relatives