Week 11, Lecture 3, Movement

Week 11 Lecture 3, - Movement and Support Hydrostatic skeletons jellyfish flatworms roundworms earthworms peristalsis alternate contraction and

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1 Movement and Support Hydrostatic skeletons - jellyfish, flatworms, roundworms, earthworms - peristalsis alternate contraction and relaxation of muscles from head to tail - good in aquatic environment Movement and Support Exoskeletons - molluscs, arthropods - hard external case of chitin (like cellulose) - growth requires shedding of old exoskeleton (moulting) Movement and Support Endoskeletons -ech inoderms,chordates - hard internal elements (bone, Ca+) - soft tissue surrounds skeleton - less restrictive for growth ... however, Pr obl ems of S ca l e Strength increases as the square of the radius (cross section of the bone) (cm 2 ) Weight increases as the cube of the radius (volume) (cm 3 ) Increase body size by a factor of 10 Strength = = Weight = = Running Flying Swimming Fig. 40.13a Body size MR Running Speed = Length x Rate Length and proportion of leg - larger body = slower speed - leg longer relative to body - proximal parts shorter than distal parts Plantigrade -so lewa lk ing - bears, humans Digitigrade - finger walking
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This note was uploaded on 04/18/2010 for the course BIOLOGY 1223 taught by Professor Gardiner/lajoie during the Fall '09 term at UWO.

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Week 11 Lecture 3, - Movement and Support Hydrostatic skeletons jellyfish flatworms roundworms earthworms peristalsis alternate contraction and

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