Arthropod exoskeletons are made of cuticle and can be both strong and flexible.
The polysaccharide chitin is often found in arthropod cuticle.
An endoskeleton consists of hard supporting elements, such as bones, buried in soft tissue
Endoskeletons are found in sponges, echinoderms, and chordates.
A mammalian skeleton has more than 200 bones.
Some bones are fused; others are connected at joints by ligaments that allow freedom of movement.
Bones and joints of the human skeleton
Examples of joints
Head of humerus
Tarsals Metatarsals Phalanges
Most animals are capable of locomotion, or active travel from place to place.
In locomotion, energy is expended to overcome friction and gravity.
In water, friction is a bigger problem than gravity. Fast swimmers usually have a streamlined shape to minimize friction.
Locomotion on Land
Walking, running, hopping, or crawling on land requires an animal to support itself and move against gravity.
Diverse adaptations for locomotion on land have evolved in vertebrates.
Energy-efficient locomotion on land
Flight requires that wings develop enough lift to overcome the downward force of gravity.
Many flying animals have adaptations that reduce body mass.
For example, birds lack teeth and a urinary bladder
What are the energy costs of locomotion?
Body mass (g)
Energy cost (cal/kg•m)
You should now be able to:
Distinguish between the following pairs of terms: sensation and perception; sensory transduction and receptor potential; tastants and odorants; rod and cone cells; oxidative and glycolytic muscle fibers; slow-twitch and fast-twitch muscle fibers; endoskeleton and exoskeleton.