Nonhuman Primates: Species Typical Movement
Unique ways in which different animals engage in locomotion.
From swimming to flying, there are a plethora of different movements that are specific to certain animal types and their environments. Animals have specifically developed bodies that allow them to navigate their natural environment. For example, fish have slim bodies that allow them to cut through the density of water, with a natural buoyancy to keep them from sinking to the bottom (Schmidt-Nielsen 1972). Birds are slender with the need to carry their weight against a low-density atmosphere. Walking animals thrive in environments that contain a high-density platform upon which to walk through a low-density atmosphere (Schmidt-Nielsen 1972). However, this is not the case for all walking animals. For instance, spiders lack the muscular structure to extend their legs so they fiddle with their blood pressure to do so, and worms burrow through the dirt using bodily chemicals and muscle contractions (Schmidt-Nielsen 1972). This entry will summarize some of the more common forms of locomotion and specific movements of nonhuman species.
Brachiation is the specific movement or extending and swinging of the upper limbs as a means of moving one’s body (Turnquist et al. 1999). This movement is apparent in both human and nonhuman primates. We see this movement when we watch children on the (aptly named) monkey bars on playgrounds (Turnquist et al. 1999). This swinging motion from bar to bar – in which a child holds one bar and swings his/her weight to a second bar on which to grab – is brachiation. Although humans can engage in brachiation, it is not an efficient form of movement for them. Brachiation is usually exhibited as a form of regular movement by smaller nonhuman primates, such as monkeys and lemurs (Turnquist et al. 1999).
The hands of primates are used for many things like scratching, pulling/pushing, grasping/gripping, feeding, and grooming (Pouydebat et al. 2011). In both human and nonhuman primates, there are two broad classifications of grip – power grip and precision grip. Power grip refers to instances in which an animal grasps an object between its thumb and palm, so that the object is firmly secured in the palm of the hand (Pouydebat et al. 2011). An example of this would be the way a human grasps a bottle or a baseball. In nonhuman primates, power grips are what aid the animal in brachiation as it is how the animal can exert enough force to hold on to branches while moving (Pouydebat et al. 2011).
Precision grip refers to when animals use the tips of their finger(s) and thumb to hold an object (Pouydebat et al. 2011). When engaging in precision grip, the object being held does not get placed firmly against the palm. Precision grip is often utilized to hold small individual objects, such as a single berry or grape. Precision group is usually used to hold objects that are so small and lightweight that the added force of holding it against the palm is not necessary (Pouydebat et al. 2011).
Walking and Running
Every legged animal possesses a similar mechanism involved in locomotion. This mechanism, known as leg stiffness, is the measurement of peak ground force to peak leg compression in a stride (Shen and Seipel 2015). SLIP or spring-loaded inverted pendulum is the model of locomotion that looks at leg stiffness as a mechanism, which illustrates the similarities between different types of locomotion like hopping and walking (Shen and Seipel 2015). The SLIP model postulates that most legged animals have a spring system of locomotion which allows an animal’s individual leg movements to propel it forward. Imagine an animal in stationary standing position. As the animal begins to lift its leg to take a step, the SLIP model is utilized to measure the arch of the leg and the pressures surrounding it all the way until the animal is standing again or taking another step. This arching movement is said to look on paper like a pogo stick springing forward (Shen and Seipel 2015). At each step there are different pressures between the leg, the bend of the knee, and the ground (Shen and Seipel 2015).
Fish are special creatures as their movement through a dense medium forces them to be streamlined in shape (Schmidt-Nielsen 1972). This streamlining refers to the elongated shape that deflects the atmosphere smoothly around the fish. This allows the fish to move the water around its body as smoothly as possible, decreasing the caloric expenditure of swimming by moving parts of their body in a manner that utilizes drag to create propulsion (Schmidt-Nielsen 1972). The two main types of propulsion – anguilliform propulsion and carangiform propulsion – are utilized by different aquatic species. For instance, eels engage in anguilliform propulsion, which is a form of propulsion in which the animal uses its entire body to move forward (Schmidt-Nielsen 1972). Species that use carangiform propulsion, such as sharks and salmon, use the movement of their tail fin to generate propulsion (Schmidt-Nielsen 1972).
Locomotion takes many different forms, each of which is specific to certain animals and the atmosphere of their natural environment. This entry focused on multiple different mediums of motion – swimming, walking, grip, and brachiation – to illustrate how species adaptation to an environment can dictate the type of movement in which that species engages. For instance, animals adapted for land living – such as primates – do not swim as efficiently as animals like fish that have adapted for water living. The evolution of environment-specific locomotion has allowed every species to better navigate and survive in their natural environment by allowing them to search for food, evade predators, and seek shelter from other environmental hazards. However, every type of locomotion utilizes a complex process of muscular movement and metabolic activity and therefore should continue to be researched.