Kinesis and Taxis
Nearly all animals are mobile at some point in their life. For some lower
animals, movement is undirected and random, such as a Paramecium blundering
about its environment. Such undirected orientation is called kinesis. In
contrast to kinesis, taxis is the term for movement in response to some
stimulus. Taxis involves more complex behavior than kinesis, and is generally
what we think of when we think of movement.
Different taxes (plural of taxis) result in response to different types of
stimuli. Each of these forms of taxis can be described by simply adding a
prefix to the word taxis. The table below shows the most common forms of taxis.
Figure %: Important Taxes
From these terms we can describe almost any directed movement. For instance,
phototaxis would be movement in response to light. Chemotaxis means movement in
response to a chemical. Any combination of these words can be used. Movements
toward a stimulus are positive taxes, while movements away from the stimulus are
Important Examples of Taxis
makes clear the variety of types of taxis. Below we will
provide some examples.
- Menotaxis refers to an animal maintaining a constant angle to a stimulus.
The Silkworm moth, for instance, flies at an angle perpendicular to the
direction of the wind in order to pick up a scent trail. Once the moth detects
the trail, it turns upwind to find the chemical gradient of the trail. Another
type of menotaxis is sun compass orientation. Many animals use the position of
the sun to orient themselves. These animals can compensate for the sun moving
across the sky over the course of the day. Honeybees for instance, imprint on
the arc of the sun. They can utilize polarized light, and so they can locate
the position of the sun even on an overcast day.
- Tropotaxis refers to taking signal samples simultaneously from paired
receptors. From , we can see tropotaxis literally means
"turned movement." Animals taking samples from paired receptors often zigzag
about the trail. An experiment by Martin and Lindauer revealed that crossing
the antennae in honeybees results in the bees traveling in the opposite
direction from where the trail would lead them.
- Magnetotaxis is orientation in response to magnetic cues. Wide varieties
of animals use magnetic cues to navigate. Aquaspirillum bacteria burrow in the
mud, and use the magnetic field of the earth to determine position. In the
Northern Hemisphere, they direct themselves to the northern magnetic pole, which
is actually the geographical South Pole, and so burrow down into the mud. In
the Southern Hemisphere, they orient towards the geographical North Pole, which
is a magnetic south pole.
- Telotaxis, or goal-directed movement, describes the motion of visual
predators who can see a distant visual signal and move to attack.
- Klinotaxis refers to movement through a gradient while taking successive
samples of the environment.
- Mnemotaxis, literally "memory movement", describes navigation through the
use of landmarks. Many birds navigate using landmarks, as do salmon. Humans
also use mnemotaxis when navigating through the use of street signs and familiar