LOCOMOTION 2
Other Terrestrial Locomotion Types of Mammalian Locomotion
Types:
Ambulatory (walking)
Examples: Humans and elephants.
Note: Cheetah is the fastest land mammal.
Scansorial (scampering)
Examples: Most rodents and insectivorous mammals.
Saltatorial (ricochetal or bipedal hopping)
Examples: Kangaroos and several rodents.
Arboreal (tree-dwelling; rarely on ground)
Examples: Squirrels and some monkeys.
Brachiation (swing through trees; forelimbs only)
Example: Spider monkeys.
Fossorial (travel through earth)
Examples: Moles and pocket gophers.
Aquatic
a) Semi-aquatic (amphibious): Examples include pinnipeds.
b) Fully aquatic (obligate): Examples include cetaceans and sirenians (can out-swim fish).
Gliding (non-powered "flight")
Examples: Dermopterans and flying squirrels.
Aerial (powered flight)
Example: Bats (capable of out-maneuvering birds, with the exception of hummingbirds).
Saltatorial Locomotion
Saltation:
Defined as bipedal (two-footed) hopping.
Notable examples include rodents and kangaroos, which demonstrate convergent evolution.
Characteristics:
Enlargement of hindlimbs and reduction of forelimbs.
Tendency to inhabit open areas such as deserts.
Energy-efficient at high speeds over long distances, utilizing energy stored in spring ligaments.
Most examples of saltatorial locomotion are small animals because large or heavy mammals tend to find this energetically expensive. (Kangaroos are an exception.)
Kangaroo Locomotion Analysis
Speed versus Energy Consumption:
Data analysis presented as a table relating speed in km/hr to oxygen consumption:
At 8 km/hr:
Energy is expended in spring ligaments as speed increases, resulting in a greater metabolic cost initially.
Above 8 km/hr, spring ligaments assist in locomotion, thereby decreasing the oxygen consumption.
Performance comparison:
Kangaroo pentapedal versus bipedal locomotion analysed alongside quadrupedal wolf locomotion shows:
No gait change at varying speeds.
The wolf spends less energy than kangaroos at lower speeds (below 8 km/hr), leading to less effort in overcoming initial energy expenditures.
Kangaroo Adaptations and Studies
Pentapedal Locomotion:
Research focuses on the mechanics of kangaroo locomotion, specifically, the role of their tails in movement.
Findings indicate that the tail is responsible for approximately 30% of mechanical power during locomotion. Measurements include:
Vertical force in %BW (body weight) during different phases of a stride cycle.
Force and power generation by tail, hind, and forelimb limbs, demonstrating the mechanics of propulsion and braking.
Important Article Reference:
O'Connor SM, et al. (2014), "The kangaroo's tail propels and powers pentapedal locomotion", Biology Letters, 10: 20140381.
Climbing Locomotion Types
Types of Climbing Locomotion:
Scansorial:
Generalized climbing mechanism, not highly specialized but does possess adaptations for tree living.
Adaptations include:
Curved claws and calloused foot pads.
Long tails for counterbalancing.
Gliding:
Involves expansion of tissues between forelimbs and hindlimbs, primarily seen in some rodent families (Sciuridae, Anomaluridae) and Dermoptera (Cynocephalidae).
Arboreal:
Highly specialized for precise movements, with adaptations for better grip such as:
Opposable thumbs.
Increased friction through palm and sole adaptations, liberal numbers of sweat glands.
Fingerprints and calloused foot pads.
Some species exhibit prehensile tails.
Skeletal adaptations for complex movements include:
Non-fused radius and ulna for novel hand/foot rotation.
Spherical heads of long bones.
Rounded distal ends of radius and ulna for enhanced movement in two planes.
Increased length and decreased weight in bone structure.
Deep sockets in shoulder joints for strength and resistance against dislocation.
Sensory adaptations include enlarged cerebellum and forward-facing eyes for improved spatial awareness and grip.
Brachiation and Other Locomotion Types
Brachiatory adaptations:
Specialized for swinging and rapid movements, with changes on top of existing arboreal modifications such as:
Strong shoulders that primarily utilize forelimbs.
Stiff, hook-like fingers due to loss of opposable thumbs.
Fossoriality:
Few mammals burrow through the earth for food – notable examples include moles and pocket gophers.
Advantages: Rarely exposed to predators.
Disadvantages: Energetically costly to dig through soil.
Adaptations include:
Small, fusiform shape (cigar-shaped).
Strong claws and teeth for digging, requiring power rather than speed or coordination.
Stocky and muscular builds with large olecranon processes and low gear ratios for strength.
Solitary behaviors with enhanced olfactory and auditory capabilities, featuring valvular ears and noses for improved sensory experience.
Aquatic Locomotion
Modes of Propulsion in Water:
Variations exist based on limbs or tails used:
Seals (Phocidae): Use hind flipper propulsion.
Sea Lions (Otariidae): Rely on front flipper propulsion.
Sea Otters: Move using hind limb propulsion.
Dolphins: Employ a unique “dolphin kick” and echolocation for navigation.
Blue Whales: Use a similar propulsion method to dolphins, steering with their fore flippers.
Aerial Locomotion
Mammalian Flight:
Only bats exhibit true flight among mammals, showcasing various wing morphologies based on their foraging strategies:
Carnivores: Hunt using sharp claws and flight abilities.
Piscivores: Fish-eating bats, noted for their significant claw size on feet.
Nectar feeders: Capable of hovering, possessing long tongues adapted for feeding.
Insectivores: Utilize echolocation techniques and distinct foraging strategies to catch prey.
High flying insectivores: Have pointed wings and high aspect ratios for fast flight.
Additional Resources and Videos
Links provided to visual resources for better engagement and comprehension of locomotion types:
Saltatorial locomotion videos, arboreal adaptability videos, brachiation examples, and more, found through links to Youtube and Vimeo.