Support & Locomotor Adaptations

Locomotor Adaptations

• Plantigrade (ambulatory)

• Cursorial (running)

• Jumping

• Amphibious, Aquatic, and Marine

• Fossorial

• Graviportal

• Arboreal

• Brachiation

• Gliding

• Flying

Plantigrade (ambulatory)

Walking using your whole foot

Ambulatory = walking

Plantigrade = using whole foot

Plantigrade characteristics

• Pentadactyl (5 toes)

• Joints distal to pelvic and pectoral girdle (elbows, wrists, knees, ankles) are restricted to movement in a single plane

• Reduced musculature in legs (increases momentum)

• Reduced or absent clavicle

  • Allows for shock absorption

  • Increases mobility

  • Increases stride length

Jumping Locomotion Categories

• Saltatorial

• Ricochetal

Jumping traits

Stocky appearance with center of gravity shifted posteriorly

Many have a longer tail for balance

Saltatorial Definition

Jumping on all fours

Ricochetal definition

Jumping only with hind feet (seen in kangaroos)

Amphibious Animal Locomotion

• Fimbriation

  • Acts like webbing

• Association with water is a secondary adaptation

  • Started as fish → moved to amphibious → moved to mammals being all terrestrial → some mammals went back to being aquatic

• Thick hair

  • Water CANNOT penetrate hair

    • Skin remains dry

• Modified tails

  • Think of alligators swimming and swishing their tails

Fimbriation Definition

Stiff ridge of hair between toes

Aquatic Animal Locomotion

• Marine animals that only come onto land to reproduce

• Pinnipedia

  • Pinnipeds include seals, sea lions, and walruses

• Body mass is mainly anteriorly location

  • NO ASS

• Tail is generally reduced or absent

• Bony elements of hands or feet are supported in a paddle-like fin or flipper

• Adaptations to reduce drag in water

Marine Animal Locomotion

• Category of animals with the greatest adaptations

• Never leave the water

  • Reproduce in water, live in water, etc

• Includes whales and manatees

• Nostrils on dorsal portion of skull

  • Nostrils can be closed with valves

• Skull is telescoped

  • Parts of their skull have been compacted and parts of their skull have been stretched out

• Fusiform body (reduces drag)

  • Increases laminar flow = the smoothness of the movement of water over a surface

• Mostly hairless/naked (reduces drag in water)

• Greatly modified skeleton

• Posterior appendages are gone

• Modified tail

  • Fluke used as propulsion

  • Front appendages/forelimbs used for stabilization and steering

Fossorial

Animals that spend majority of time underground

• Moles, gophers, etc

Fusiform body (usually)

Legs tend to be short

Pectoral girdle is greatly modified for digging

Moles are extremely strong

Greatly enlarged surface area on clavicle and scapula

No nape on fur (no way that hair lies naturally)

Auditory and visual senses are vestigial or even completely absent

Enhanced olfactory and tactile perception

Why are auditory and visual senses reduced or absent in fossorial animals?

Sound in solid objects travels much faster than it does in air, so you are unable to know which direction the sound is coming from

Graviportal

Less about HOW you travel and more about WHY you travel this way

Has to do with weight (less about flexibility)

Limbs are supporting a ton of weight

• Do not bend legs when walking

  • Limbs move straight up and down

Radius and ulna are the same size in order to support the heavy body

Fibrous disc that sits underneath toes to cushion feet that support their weight

• Like holding a foam dodgeball in your hands and then leaning on them

Arboreal

Variety of adaptations from squirrels to sloths

Animals that spend most of their time in trees

Arboreal (Sloth) Adaptations

Extremely strong shoulder girdle

Increased number of ribs (to support internal organs in a “basket”)

Extremely flexible neck

• Sloths have additional cervical vertebrae (9)

Greatly reduced senses

• Poor vision and poor hearing

Arboreal (Squirrel) Adaptations

Body somewhat elongated

Extremely long legs

Extremely sharp and well-developed claws (for climbing)

Senses are extremely well-developed

• Heightened for climbing thin trees and jumping from branch to branch

Brachiation Adaptations

Flexible, strong, lengthened arms

Well-developed claws and nails

Pollex is NOT well-developed (thumb)

Well-developed friction pads on fingers

Heightened senses

• Stereoscopic/binocular vision

  • Crosseyed to be able to judge distances

Gliding Adaptations

Seen in flying squirrels and lemurs

Flaps to increase surface area

Tail is flattened and feathered

Can spread flaps further and flap = transition to flying

Flying Adaptations

Seen in bats

• Flight enhanced for both slow flight and maneuverability

• Bats essentially swim through the air, using their legs as an extension

Wings as an extension of skin from wing tip to belly that goes back and encases forelimbs

Inner part of wing achieves lift (to offset gravity)

Fingers achieve thrust (to offset gravity)

Can change shape of wings for flying and landing

Wing load

Aspect ratio

Keeled sternum

• Muscle attachment on pectorals

Weight

• Bats do not have hollow bones

  • Need to be able to make enucleated erythrocytes

  • Bats just have really THIN bones