27-1 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Chapter 27: Animal movement 27-2 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Locomotion All animals can move at some stage in their life cycle example: sponges are sessile as adult but have motile larvae Locomotion requires the exertion of force on the surrounding environment land, air, water Two categories muscular non-muscular (cilia, flagella) 27-3 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Aquatic locomotion Buoyancy tendency for an object to float interaction between upthrust ( ) and gravity ( ) Positive buoyancy object rises ( > ) Negative buoyancy object sinks ( < ) Neutral buoyancy object remains in position ( = ) 27-4 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Positive and negative buoyancy Positive buoyancy overall density of organism lower than that of water example: Physalia with gas-filled float Negative buoyancy overall density of organism greater than that of water example: benthic organisms Both require organisms to expend energy to remain at a constant depth not rise or sink 27-5 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Neutral buoyancy overall density of organism same as that of water Neutrally buoyant animals have mechanisms for changing overall density of body Reduces the energy expenditure associated with maintaining vertical position (cont.) 27-6 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Neutral buoyancy (cont.) Gas-filled structures Nautilus shell chambers fish swim bladders Gases can be excreted or secreted to allow animal to vary buoyancy Some sharks have high levels of lipid in liver to reduce overall density slight negative buoyancy 27-7 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Fig. 27.1: Nautilus (a) (b) Copyright Mike Tinsley/AUSCAPE 27-8 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Muscular locomotion Jet propulsion expelling water to push animals in opposite direction Underwater flying flapping forelimbs in flight movements Rowing moving forelimbs backwards and forwards in oar-like movements Body undulations trunk muscles and tail fin used to propel animal 27-9 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Non-muscular locomotion Cilia and flagella only effective in small organisms protists many invertebrate larvae Extensions of cytoplasm exert force on water multiple cilia one flagellum or several flagella 27-10 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Fig. 27.2: Beating of a cilium 27-11 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Aerial locomotion Flying animals use unpowered flight little energy expenditure gliding parachuting powered flight substantial energy expenditure muscle-powered flapping 27-12 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Unpowered flight Gliding animals extend body surface to increase lift Force of lift depends on speed of flight size of wing (aerofoil) shape of wing tilt (angle of attack) of wing Gliding requires minimal energy expenditure maintenance of posture 27-13 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Gliding Most gliding animals can alter shape of gliding surface to modify performance speed decreased for landing speed increased in intercepting prey Soaring is employed by birds that use powered flight gliding on thermals rising from warm land Slope soaring soaring in wind rising along a slope, so bird remains stationary relative to ground 27-14 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Powered flight Requires significant energy expenditure to flap wings but more efficient than terrestrial locomotion Downstroke acts against air to provide lift and thrust wing fully extended to maximise lift and thrust Some birds and bats hover by producing lift on downstroke and upstroke high energy expenditure hovering restricted to small animals 27-15 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Terrestrial locomotion Techniques for terrestrial locomotion are varied Without legs (protists, soft-bodied invertebrates) amoeboid locomotion peristalsis pedal waves With legs (invertebrates, vertebrates) crawling walking jumping 27-16 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Locomotion without legs Amoeboid locomotion single-celled organisms extend finger-like pseudopodia over substrate Peristalsis segmented worms typically use peristalsis to crawl and burrow interaction of muscles and hydrostatic fluid change shape of segments Pedal waves waves of muscular contraction on underside of snails foot 27-17 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Locomotion with legs Legs raise body off ground to decrease amount of body in contact with ground Reduced contact decreases stability Stability increased by lower centre of mass increased area of contact (larger feet, more limbs) larger area enclosed by contact points 27-18 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Walking and running Animals change gaits at different speeds example: horses walk trot gallop Energy expenditure increases with increasing speed Within each gait there is a speed at which energetic cost is minimal 27-19 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Jumping Kangaroos use pentapedal (four limbs + tail) locomotion at low speeds Hopping is more efficient than pentapedal locomotion at higher speeds 27-20 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Skeletons Skeletons provide support for muscles support against gravity Types of skeletons hydrostatic fluid-filled exoskeleton rigid, external rigid endoskeleton rigid, internal 27-21 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Hydrostatic skeletons Soft-bodied animals (deformable body wall) Fluid-filled body cavity Action of muscles shunts water around one or more cavities, changing shape of body Body capable of extension and contraction example: annelid (segmented) worms 27-22 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Exoskeletons External skeleton of chitin (+ minerals in some species) Thick and rigid plates (sclerites), thin and flexible between plates Muscles attached to inside of skeleton Must be moulted periodically to allow growth 27-23 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Endoskeletons Internal skeleton of cartilage and/or bone bone can be remodelled to accommodate changed loads increases in mass in response to increased loads decreases in mass in response to decreased loads Muscles attached to outside of skeleton Endoskeleton grows with the organism 27-24 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Joints Exoskeletons and endoskeletons both have rigid components Joints allow flexibility between the components muscle produces force bones or other skeletal elements act as levers Joints can be classified by degree of mobility sutures are fixed and immovable (e.g. skull) slightly movable joints (e.g. intervertebral discs) freely movable joints (e.g. elbows, shoulders) 27-25 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Muscle structure Skeletal muscle cells (fibres) are cylindrical, multinucleate and have a striated (striped) appearance striations due to arrangement of actin and myosin filaments in sarcomeres Infoldings of sarcolemma (muscle fibre plasma membrane) ramify through fibre transverse (T) tubule system 27-26 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Fig a: TEM of mammalian skeletal muscle 27-27 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Skeletal muscle mechanism Mechanism of skeletal muscle contraction is explained by the sliding filament model Actin filaments slide relative to myosin filaments draw Z-discs towards centre shorten sarcomere muscle contracts 27-28 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Sliding filaments When resting, myosin heads are unable to form cross-bridges with actin Myosin binding sites blocked by tropomyosin When an action potential depolarises sarcoplasmic reticulum, Ca 2+ binds to troponin-tropomyosin complex, exposing myosin binding sites Myosin binds to actin filament (cont.) 27-29 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Sliding filaments (cont.) Change in shape of myosin head draws actin filament towards centre of sarcomere Binding of ATP to myosin head causes it to detach and return to primed state It reattaches at another binding site further along actin filament 27-30 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Fig :Mechanism of muscle contraction (cont.) 27-31 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Fig :Mechanism of muscle contraction (cont.) 27-32 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Types of skeletal muscle fibre Type I fibres slow oxidative or slow-twitch fibres Type IIA fibres fast-oxidative or fast-twitch, fatigue-resistant fibres Type IIB fibres fast glycolytic or fast-twitch, fatigable fibres Type IIX fibres intermediate between IIA and IIB 27-33 Copyright 2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Slow- and fast-twitch fibres Force-production of characteristics of a fibre in response to stimulation Fast twitch fibres contraction lasts c. 10 ms Slow-twitch fibres contraction lasts c. 100 ms Distribution of muscle types depends on function of muscle Type I (slow-twitch) fibres in postural muscles Type IIB (fast-twitch) fibres in arms and shoulders