Animal MovementChapter 30

Locomotion•Active travel from place to place•Requires energy expenditures to over

come 2 forces▫Friction▫Gravity

•Importance depends on the environment

Types of Locomotion• Swimming

▫Gravity not a problem, but friction is Water supports weight, but is dense and presents

resistance▫Legs as oars, jet-propelled, and undulating side to

side or up and down▫Streamlined body shapes aids increased speed

• Locomotion on land▫Need to be able to support self and overcome gravity

Air presents little resistance, but also little support▫Energy expenditure to propel forward and keep from

falling down Muscles and skeleton more important that streamline

shape

Types of Locomotion (cont.)• Hopping

▫Tendons in legs store energy when landing, like a spring for the next jump Cost free energy boost

▫Rest with tail and hind feet on ground Costs little energy to maintain

• Walking and running▫Overcome friction between foot and ground▫Walking: 4 legged – 3 on ground all times; 2

legged – part of 1 at all times▫Running: 4 legged – 2 -3 feet move at once if not

all▫Momentum stabilizes body position

Types of Locomotion (cont.)•Crawling

▫Friction adds considerable resistance because of increased contact Undulate body side to side, inch forward, or

peristalsis•Flying

▫Wings developed to completely overcome gravity▫Shape must alter air current to create lift

Air pressure underneath is greater•All based on mircotubule or microfilament

systems. Animals in motion

Skeletons•3 main types

▫Hydrostatic skeletons▫Exoskeletons▫Endoskeletons

•Necessary for support, protection, and maintaining form

Hydrostatic Skeleton•Fluid held under pressure in a closed body

compartment•Cushions body parts from shock, gives

shape, and support for muscle action•Earthworms have coelum•Cnidarians exert pressure on

gastrovascular cavity•Can’t support terrestrial locomotion which

requires the body to be held off ground

Exoskeletons• Rigid external skeleton• Arthropods are protein and

chitin▫ Thinner at joints to allow

movement▫ Nonliving, so can’t grow

must be shed▫ Animal is susceptible to

predation and weak until new exoskeleton hardens

• Molluscs shells of calcium carbonate▫ Mantle secretes shell▫ Grows by enlarging

diameter

Endoskeleton• Hard or leathery

supporting elements among the soft tissues

• Sponges with tough protein fibers

• Echinoderms have under their skin

• Vertebrates of cartilage or cartilage and bone

The Evolved Skeleton•All vertebrates have an axial skeleton

▫Supports axis or trunk of the body▫Skull, vertebrae, and rib cage

Vertebrae all similar in structure Cervical, thoracic, lumbar, and sacral, and coccygeal

•Most have appendicular skeleton▫Bones of appendages and anchoring appendages▫Pelvic and pectoral girdle with supporting limbs

Modified versions of same bones in all vertebrates, but specialized for locomotion

Bones• Organs composed of moist,

living tissues• Pink=fibrous connetctive,

forms new bone after fractures

• Blue=cartilage, forms cushion-like surface for joints

• Inside are osteocytes that secrete bone matrix

• Yellow bone marrow is stored fat from blood to bone

• Red bone marrow produces RBC’s

Creating Movement• Tendons connect muscles to bones• Muscle action shortens or contracts muscles• The agonist moves the muscle while the antagonist reverses

the movement▫ Antagonistic pairs of muscles are found in all animals

Dissecting Muscles• Muscles consist of bundles of

muscle fibers (cells), oriented parallel to each other

• Cells are bundles of myofibrils, which are composed of the contractile proteins actin (thin) and myosin (thick)

• Proteins form a striped banding pattern that characterizes skeletal muscles

• Contractile unit of skeletal muscle is the sarcomere

Contracting Filament Model • Sarcomere contracts when

thin filaments slide over thick

• Sarcomere shortens, but length of filaments don’t change

• Heads of myosin (thick) filaments bind ATP so they can bind to actin (thin) filaments

• Head produces power stroke which moves the actin toward the center of the sarcomere when ADP is released

Muscle Fiber Types

Each muscle has a mix of the above types

Slow fibers better designed for enduranceactivitiesWeight lifting stimulates muscle fibers toproduce additional myofibrils