LSM3261 Life Form and Function

Support and locomotion

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• 1st zoology lecture - Animal diversity and basic designs

• 2nd zoology Lecture - Animal symmetry

• Organisation of the animal body;

• Transmission of messages/materials within the animal body

• Animal form and function in relation to:

• No. 3 - Protection

• No. 4 - Support & Locomotion

• No. 5 - Locomotion (Flight)

• No. 6 - Sensing the environment, Feeding; Other adaptations

LSM 3261 Life Form Structure & Function

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• To learn about various concepts and modes of support and locomotion in animals

References (pick out topics in index and contents page):

• Hickman et al., 2011. Integrated principles of zoology. 15th Ed. McGraw Hill.

• Ruppert, Fox & Barnes, 2004. Invertebrate Zoology: A Functional Evolutionary Approach. 7th Ed. Brooks Cole.

• Pough et al., 2009. Vertebrate Life. 8th Ed. Pearson International Edition.

• Young, J. Z., 1981. The Life of Vertebrates, 3rd Ed. Oxford.

• Liem, K. L., W. E. Bemis, W. F. Walker, Jr. and L. Grande, 2001. Functional Anatomy of Vertebrates. An evolutionary Perspective, 3rd Ed. Brooks/Cole.

Objectives

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Locomotion

• Major characteristic of animals: find food, escape predators, find a mate or habitat.

• Contraction of muscles results in movement

• Skeleton supports and transmits movement

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1. Hydrostatic skeleton

2. Exoskeleton (non-living)

3. Endoskeleton (living)

4. Muscular Hydrostats

I - Support

The role of an antagonist to muscle contraction.

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• Bodies of larger animals require support to function normally

• Soft-bodied aquatic species need to hold themselves up to perform certain functions (e.g. feeding). Don’t need to support their body weight

• Terrestrial species need to support body weight and require stronger support structures

Support

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Found in many soft-bodied animals

Fluid held under pressure in body or parts of body

Contraction of muscles push fixed volume of fluid from one part of body to another, transmitting force

Hydrostatic skeleton transmits force throughout the animal’s body – changing shape and movement of body

1. Hydrostatic Skeleton

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• Hydrostatic skeleton helps in locomotion

• Aquatic invertebrates without exoskeleton(e.g. Hydra, jellyfish)

• Aquatic and terrestrial invertebrates with non-living exoskeleton(e.g. insects, crustaceans, annelids)

• Aquatic invertebrates with living endoskeleton (e.g. echinoderms)

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a. Hydra

• Hydrostatic skeleton?

• Crude movements only

• No refined movements

1. Hydrostatic Skeleton

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b. Annelids

• Hydrostatic skeleton?

• Body segments separated by septa

• Fluid compartmentalised in each segment

• Each segment capable of independent movement

• Different sets of muscles can act independently in different segments

• Movement more versatile/refined

1. Hydrostatic Skeleton

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Darwin (1881) - burrowing into very

compact soils is effected by the worms

literally eating their way through it.

Newell (1950) - Radial, circular,

longtitudinal muscles and sphincters around

pores.

Ideal fluidsare incompressible, can be distorted

totally, and pressureaffecting the fluid is

subsequently exerted in all directions.

View animation at: http://

www.biology.ualberta.ca/courses.hp/zool250/

animations/Earthworm.swf

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• Earthworms and plant root both exert an axial and radial pressures to penetrate soil. The pressures exerted by roots are called “growth pressure”.

• By exerting radial pressure, the soil is broken up to allow axial penetration.

• Radial pressure is always higher than the axial pressure. By exerting a high radial pressure earthworms break up the soil in order to be able to penetrate it with a lower axial pressure.

Axial and radial pressure exerted by earthworms of different ecological groupsKeudel, M. & S. Schrader, 1999. Axial and radial pressure exerted by earthworms of

different ecological groups. Biology and fertility of soils, 29(3): 262-269.

Earthworms and plant roots both “dig” through soil

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• Bouché (1977) classified earthworms into ecological groups—anecic, endogeic and epigeic.

• The endogeic species generated a higher radial pressure because they have a higher burrowing activity due to their geophagous diet.

Keudel, M. & S. Schrader, 1999. Axial and radial pressure exerted by earthworms of different ecological groups. Biol Fertil Soils, 29: 262–269.

Earthworms dig at different depths

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http://scienceblogs.com/zooillogix/2008/05/giant_blue_earthworms_and_frie.php

Terriswalkeris terraereginae(Australian endogeic,

Family Megascolecidae, 2m)

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Giant Gippsland earthworm, Megascolides australis

usually 2-3m, record is 4m

http://scienceblogs.com/zooillogix/2008/05/giant_blue_earthworms_and_frie.php

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"It is often said that if the ground is beaten or otherwise made to tremble worms will believe that they are pursued by a mole and leave their burrows," Charles Darwin wrote

in The Formation of Vegetable Mould through the Action of Worms (1881)

Diplocardia mississippiensis collection in Florida's Apalachicola National Forest

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Hydrostatic mechanism in animalswith other types of skeletons

c. Echinoderms (e.g., sea stars, sea urchins)- possess calcareous endoskeleton

but hydrostatic skeleton moves tube feet

Hydrostatic skeleton?

1. Hydrostatic Skeleton

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• Ampulla at base of foot stores fluid.

• Valve shuts, ampulla contracts,

• fluid forced into tube feet

• (canals + ampullae + hydraulically operated, thin-walled tube feet or podia)

Fluid-filled water-vascular system

Where does the fluid come from?What is the madreporite?

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Source: Mechanical Design in Organismsby Stephen A. Wainwright (1982). Princeton Univ., 423pp.

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Hydrostatic skeleton: limitations

• Limited to aquatic or soil dwelling animals

• Water provides buoyancy, soil some support

• No protective function

• Not weight bearing: limits size

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• Secreted by epithelial tissue

• Supports body,

• gives body a fixed shape

• Rigid

• Flexibility in the form of separate pieces of plates joined by flexible joints

What other animals?

Molluscs calcareous shell

Arthropods chitinous cuticle

2. Non-living Exoskeleton

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Arthropod exoskeleton• What is it made of?

• What function does it provide the animal with?

• How is it similar to our bones?

• Which part of the insect body would you pin an insect through?

• What is moulting?

• What is an instar?

• Are all arthropods groups equally hard?

• What is the significance in museum specimens?

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Examples of exoskeletons

• Calcareous shells of clams and snails have incomplete exoskeletons for the external shells do not completely cover the animal.! Much movement still requires their hydrostatic skeleton as well so they have both an exoskeleton and a hydrostatic skeleton.

• Calcareous body coverings of crustaceans (crabs, lobsters, isopods a.k.a. pill bugs).! Crustaceans are arthropods, and like all arthropods, have a jointed exoskeleton.

• Chitinaeous body coverings of other arthropods (insects, spiders, millipedes, etc.).! When the muscle contracts, the upper part of the exoskeleton is deflexed resulting in a downward wind beat.

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• Bone, cartilage, or dentine - ostracoderm fish and turtles.

• Chitin - arthropods, also some fungi and bacteria.

• Calcium carbonate - shells of molluscs, brachiopods and some tube-building polychaetes.

• Silica - exoskeleton in microscopic diatoms and radiolaria.

• Agglutinated exoskeletons by sticking grains of sand and shell to exterior - some formanifera.

Exoskeletons are composedof a range of materials.

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• Armadillo (constructed from bone)

• Pangolin (hair)

• Reptiles

• turtle (bone)

• crocodiles (bony scutes and horny scales)

• Echinoderms?

• What sort of skeleton is the test?

Exoskeleton analogues

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• Living (connective tissue) – grows with increasing size of the animal

• Different forms:

• Almost complete armour just beneath skin (e.g. echinoderms – calcium carbonate)

• Skeletal framework to support entire body

• Skeleton built to transmit force (joints) (vertebrates – cartilage/bone)

3. Living Exoskeleton(internal skeleton)

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• Animals with non-living exoskeleton

• Armour plates with flexible joints used effectively for locomotion

• Animals with living endoskeletons

• Sea urchins, sea stars – rigid endoskeleton round body. Hydrostatic skeleton moves tube feet

• Vertebrates – internal skeleton designed for effective movement

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• Cranium (skull) [sometimes regarded as part of axial skeleton]

• Visceral skeleton - supporting gills (gill arches), jaws and tongue

• Axial skeleton (vertebral column, ribs) – supporting rest of body

• Appendicular skeleton (jointed limbs and limb girdles) – supporting rest of body

3.1 The Vertebrate Skeleton

vertebraeskull

ribs

pelvic fin (paired)

pectoral fin paired)

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• Aquatic species

• Less need to support body weight

• Streamlined

• Terrestrial species (tetrapods)

• Must support body weight

• Development of pentadactyl limb

3.1 The Vertebrate Skeleton

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Vertebral column elongated

Built to withstand compression

Limb girdles reduced

Aquatic vertebrates

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• Vertebral column

• Shortened

• Greater rigidity

• Appendicular skeleton

• Well developed

• Development of pentadactyl limb

Terrestrial vertebrates (Tetrapods)

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General shortening of

vertebral column as the

animal becomes more terrestrial

(Part that is involved in

locomotion)

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The rigid vertebral column in tetrapods, acts as a girder because limbs bear the full body weight

(cf. fish: flexible, less ossified,constructed to withstand compression during locomotion,

while aquatic medium bears body weight)

Emphasis on strength and rigidity instead of flexibility

Importance of the rigid vertebral columnin tetrapods

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skull vertebral column

pectoral girdle

pelvic girdle

frontlimbs hind

limbs

Axial skeletonSkull

Vertebral column

Appendicular skeletonPectoral and pelvic girdles

Paired limbs

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Hypothesised stages in evolution of the pentadactyl limb

A skeleton with stronger and more rigid limbs to lift body off the ground (cf. fins) led to the development of pentatdactyl limb.

Hypothesised stages in evolution of pentadactyl limb from fish fin:

(a) Elongation

(b) Bending

(c) Develop another joint (wrist/ankle) - greater surface area contact with ground for better balance

(d) Shifting of limbs from lateral to ventral side for greater leverage

(e) Orientation of limbs for speed (lateral view)

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• Terrestrial vertebrate (e.g. amphibian):

• Flattened with loss/reduction of most dermal bones

• Large cavities (e.g. orbits). – lighter skull

• No operculum

• Hind part (in fish, concerned with gills and pharynx) becomes reduced

• Cf. Aquatic vertebrate (e.g. fish):

• Deep, heavily protected by many dermal bones, large operculum to protect gills. – supported by water

Liem et al., 2001

Lightening skeletal weight, particularly in terrestrial animals.

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Similarities between arthropodand vertebrate design

- the articulated skeleton

• Articulated skeletons - skeletal components meet or articulate at the joints, allowing one part of the body to move in relation to another.

• Muscles spanning joints and anchored to different parts of the skeleton provide the power for movement.

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Similarities between arthropod and vertebrate design

- the articulated skeleton

Articulated skeletons serve two functions.

• They allow the retention of a characteristic physical form.

• They support an organism’s weight and resist the stresses of locomotion.

• What kind of animal structure provides protection, but does not define an animal’s form or support its weight?

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The Articulated Skeleton

• Two novel parallels in arthropod and vertebrate evolution -

• both are the most successful of all terrestrial animals

• both are the only organisms ever to evolve an articulated skeleton

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4. Muscular Hydrostats

Densely packed three-dimensional array of muscle fibers.

Lack the rigid elements of skeletal support systems

Lack the fluid-filled cavities of hydrostatic skeletons

This musculature generates forces for movement, deformation and changes in stiffness and skeletal support.

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Examples: arms and tentacles of cephalopods, tongues of mammals and lizards, trunk of the elephant

Kier Lab, UNC Chapel Hill

4. Muscular Hydrostats

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Also in manatee, possibly in the dugong also?

4. Muscular Hydrostats

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A dynamic skeletal support system.

Rigid skeletal elements are restricted by joints; Muscular hydrostats can deform - bend, elongate, shorten and twist at any location and at multiple

locations simultaneously

Muscular hydrostats can highly localise deformations, unlike hydrostatic skeletons. E.g.

octopus arm or tongue,

4. Muscular Hydrostats

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Different strategies for different densities

II - Locomotion in water, land and air

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Locomotion in water, land and air

Water Land Air

No need to support body weight

Need to support body weight

Need to support body weight

Can remain sessile or sedentary;

nekton must be active

Must actively generate propulsive force

Need to cope with pressure

Can remain suspended in water column

Need to move in search of food, resources

Need to keep moving at all times

Need to maintain balance in 3D perspective

Need to maintain balance (2D medium)

Must maintain good sense of balance in 3D perspective

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Aquatic medium

! Can remain sessile or sedentary (need holdfast mechanism)

! Can be strong swimmers

! Generally carried about by currents

! Support limbs reduced

Locomotion in water, land and air

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• Beating antenna or flagella - smaller forms

• Flex cup shaped bodies or drift (passive) (jellyfish etc)

• Undulation of body (vermiform organisms in many phyla), arms (feather stars)

• Paddling with special swimming legs (crustacean pleopods or pereiopods)

• Flapping fin-like structures, e.g. clapping two shells

• Propulsion - jet (cephalopod) and tail (fish)

• Energy demands - buoyancy and sudden movement

Modes of Swimming

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Swimmers

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Unpaired fins(dorsal and anal fins)counter yaw, roll

Paired fins(pectoral and pelvic fins)

counter pitch

Pectoral finsalso used for

braking, steering

Side-to-side oscillation of vertebral column

Stabilisation of fish in a 3D fluid medium

(cf. stiff, inflexible pectoral fins of sharks used as hydrofoils)

cf. flight in birds later

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sprawling erectsemi-sprawled "high walk"

Wired 2010

Modes of locomotion

• Legged

• sprawling, e.g. lizards, insects, also mudskipper, octopus

• semi-erect, i. e. elevated sprawling, e.g. monitor lizards, crocodilians

• fully erect, e.g. mammals , birds

• Also limbless, rolling

Terrestrial Medium

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Belly clear off ground!

• Terrestrial animals with skeletons use their limbs to walk, trot, run, leap, brachiate, and fly.

• Since arthropods and vertebrates are typically with bellies clear off the ground, the body passes through air instead of over the ground with friction.

• The foot of a running arthropod or vertebrate touches the ground long enough to propel the animal forward with each stride. I.e. moves swiftly, cf. ground-bound, soft-bodied animals.

“A Vertebrate Looks at Arthropods,”by Barbara Terkanian.

Arizona-Sonora Desert Museum, c. 2006.

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Crocodiles high walk and belly crawl over land

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Crocodilian locomotion

• Floating - hind limbs splayed out in water with toes and toe webbing extended (submerge backwards by upward movement of spread limbs)

• Swimming - limbs held against body, undulation

• Diving - front limbs lifted almost vertically, protrude above the shoulder to direct head downward

IUCN Crocodile Specialist Group

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Crocodilian locomotion

• High walking - most common gait: limbs held erect beneath body, tail drags

• Sprawling - rapid movement on land: front and back legs on one side meet when body curves, then separate, tail thrashes from side to side in synchrony

• Sliding - going down steep mud banks: drag limbs, tail moves side to side for propulsion

IUCN Crocodile Specialist Group

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Crocodilian locomotion• Galloping - Australian Freshwater

Crocodiles (Crocodylus johnsoni) gallop almost every time they need to move rapidly on land.

• Front limbs go out and forward as the hind limbs propel the body forward.

• Tail tends to move up and down rather than from side to side.

• Maximum speed about 18 km/h (cf. 2-4 km/h high walk); but exhausted by 100 m

IUCN Crocodile Specialist Group

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3.1 Cursorial locomotion in hoofed animals

3.2. Arboreal and terrestrial habits in primates

3.3. Graviportal locomotion in large, heavy terrestrial mammals

3.4. Swimming in aquatic mammals

3.5 Adaptations of vertebral column

III. Adaptations of the pentadactyl limb & vertebrate skeletonMammals demonstrate a wide variety of adaptations of the pentadactyl limb and skeleton for different modes of locomotion

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Ability to run fast - another form of defence

• Skeletal modifications of pentadactyl limb:

• Limbs lengthened and modified for cursorial locomotion (fast running)

3.1 Cursorial locomotion in ungulates (hoofed animals)

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Skeletal modifications of pentadactyl limb:

• Elongation of lower limb segments; shortening of upper segments.

3.1 Cursorial locomotion in ungulates (hoofed animals)

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http://www.cartage.org.lb/en/themes/sciences/Zoology/Animalclassification/OrderPrimates/posture.jpg

Skeletal modifications of pentadactyl limb:

• Locomotion digitigrade (on all digits), developing into unguligrade (on main digits, others reduced or lost)

Fast running:Distal sections

elongated.

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• Hoof formation - terminal phalanges touching the ground becomes broad, with claw surrounding it

• The long metapodials (metacarpals and metatarsals) fused together to form a cannon bone (in horses): 5 toes to 3 toes to 1 toe - toenail

• Upper limb muscles play an important role in moving the limbs

3.1 Cursorial locomotion in ungulates (hoofed animals)

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Foot = toes to anklesAnkle bones

Metatarsals

Plantigrade – entire hand/foot in contact with ground. Weight borne

by metacarpals (palms) and metatarsals (sole of foot) .

Digitigrade – Only digits in contact with ground. Weight borne by digits (fingers and

toes).

Unguligrade – Tips of main digits in contact with ground. Digitigrade but lateral digits failing to reach ground are

reduced or lost.62

Cannon bone

Ungulates

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Cannon bones odd-

toed

even-toed

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Ungulate = a mammal with hooves

• Perissodactyla (odd-toed mammals) - horse, tapir, rhinoceros spp.

• Artiodactyla (even-toed mammals) - all other ungulates.

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The Artiodactyls are more successful than the Perissodactyls

• Perissodactyls appeared in late Palaeocene epoch and were most diverse during the Eocene epoch.

• Artiodactyls appeared in early Eocene and radiated in the Miocene epoch during which the perissodactyls declined.

• From Cenozoic era to present, Artiodactyla - 36 down to 10 families (81 genera); however, Perissodactyla - 14 down to 3 families (5 genera).

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3.2 Arboreal and terrestrial habits in primates

Primates

Apes- great apes- lesser apes

Monkeys- old world- new world

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• Family Hylobatidae

• 15 species in four genera: Hylobates, Hoolock,Nomascus and Symphalangus

• Master brachiators

Gibbons, lesser apes

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Modification of pentadactyl limb designin primates arboreal adaptations

Pentadactyl plan retained without loss or fusion of bones

Hand and foot modifiedfor grasping:opposable thumb (pollex)and toe (hallux)

Claws of digits transformed into flat nails

Young, 1981

3.2 Arboreal and terrestrial habits in primates

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Tarsier (a Southeast Asian primate)

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New World monkeys VS Old World monkeys

more arboreal

prehensile tails

Arboreal and terrestrial habits in primates

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Large apesnot always possible to walk on

branches like the monkeys(quadrupedal)

BrachiateInstead they swing by their arms which have become longer than

their legs

Knuckle/fist-walkingWhen on the ground,

apes cannot remain upright for long need to prop themselves up

with their handsin a semi‑erect posture

Arboreal and terrestrial habits in primates

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Gibbons and organ‑utans more arboreal, chimpanzees and gorillas more terrestrial.

Feet of chimpanzees and gorillas more adapted for walking ‑ broader soles and shorter toes

In gorillas, like man, the hallux occupies a position parallel to the other toes

Young, 1981

Arboreal and terrestrial habits in primates

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Adapted for arboreal life

Adapted for terrestrial life

Arboreal and terrestrial habits in primates

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Graviportal system

Neural spines

3.3 Graviportal locomotion in heavy animals! Large body mass supported mainly by stout pillar-like front legs rear legs push! Vertebral column with long neural spines and numerous ribs! Heavy head counter-balances body weight, pivoting on front legs! Relatively slow movement

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Rhinoceros body is graviportal, like that of elephants:

! Vertebral column with long neural spines above the foreleg,

! numerous ribs, almost reaching pelvis.

! Whole column forms single girder balanced on the forelegs,

! The large, heavy head provides a counter-balance to the body weight

Graviportal locomotion in heavy animals

Florida Department of Education, Office of

Educational Technology.

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Young, 1981

! Stout pillar-like front legs that take the main body weight

! Hind limbs act to push the animal forwards

! Tall neural spines and large ribs for attachment of muscles to support front legs

! Enables heavy animals to climb up hill slopes.

Graviportal locomotion in heavy animals

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http://www.stephanecompoint.com/41,,,3504,en_US.html

Baluchitherium (Indricotherium)the largest land mammal of all time

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extinct perissodactyl

extinct primitive rhinoceros -

Indricotherium

Graviportal locomotion in heavy animals

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" Graviportal locomotion and similar forms evolved independently in unrelated groups of terrestrial animals, resulting in convergence of general form.

• Associated with attaining large to huge sizes

• Living examples: elephant, rhinoceros, giraffe, bison, oxen

• Was seen in the largest dinosaurs (sauropods).

sauropod dinosaur

Graviportal locomotion in heavy animals

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Brachiosaurus

Graviportal locomotion in heavy animals

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Graviportal locomotion in birds

GraviportalA type of locomotion in which the limbs are large,

straight and sturdy and bear a large body mass (e.g. elephant).Usually alludes to slow-moving, weight-bearing terrestrial movement

Cf. CursorialRunning locomotion in which the limbs are long and slender,

and not associated with bearing a large body mass(e.g. antelope). Alludes to animals adapted to running.

Graviportal characterslarge, heavy leg bones arranged in vertical columns

as supports to heavy body mass.

Graviportal locomotion in heavy animals

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Graviportal characters seen in extinct, flightless birdsE.g.: elephantbirds (Aepyornithiformes) [Madagascar]

moas (Dinornithiformes) [New Zealand]

cf. Modern flightless birds (e.g. ostrich), which have cursorial characters (slender legs; reduced toes ! reduced contact with

ground while running)

Pough et al., 1990

Graviportal locomotion in heavy animals

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3.4 Skeletal adaptations of

mammals returning to the aquatic

environment

Seals, sea lions, walruses, dugongs, manatees, whales, dolphins,

porpoises

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Whales, dolphins and porpoises

Flipper-like forelimbs and large dorsal fin for stability

Tail and dorsal fin = neomorphs (new structures evolved in response to returning to water. Skin folds without skeletal support)

Only fore flippers have skeletal support ! modified from fore limbs. Hind limbs disappeared completely and pelvic girdle reduced

Vertebral column reverts to similar form as fishes, i.e. a compression structure for aquatic locomotion. With absence of neck. Movement

involves dorso-ventral undulations of vertebral column (cf. fishes)

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3.5 Adaptations of vertebral columnImportance of rigid vertebral column

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Extension/flexion of vertebral column

Fish-like side-to-side oscillation of vertebral column

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