Otter in suspension

A travelling animal can employ various gaits, a word that describes the pattern of movement of limbs during locomotion. A bipedal human might walk, hop, or run, each a different form of propulsion. The transition from one gait to another takes place when the energy it takes for, say, a fast walk begins to exceed that of a slow run. Quadrupeds, such as a horse, deer, or dog often have a wider range of choices which might include: walk, amble, pace, trot, canter, gallop, run, or stot. 

A trotting mule deer is in suspension (2011).

A characteristic of some of the faster gaits is a period of suspension: a time when all four feet are off the ground. It seems that the faster the animal moves, the longer the period of suspension: Aerial time matters for speed.

Many rapidly moving quadrupeds exhibit a period of suspension.

Do otters?

A 2002 paper that studied the running energetics of the River Otter noted that:

… the ability to incorporate a period of suspension during high speed running was an important compensatory mechanism for short limbs…. Such an aerial period was not observed in river otters….

An otter family walking; None are in suspension (2015).

It is interesting that the authors of this study did not see a running otter in suspension. I do not know how the paper’s authors motivated the otters to run, yet that motivation clearly wasn’t sufficient to prompt them to excel.

I recently watched two otters in suspension while they were running and the motivation seemed to be purely that of having fun — otters, after all, will be otters.

This running otter is in suspension. It was racing along a dock before making a great leap into the water — rather like a child racing up a diving board before leaping off the end. The first otter was followed by a second that did likewise. It seems that pleasing a researcher isn’t as important to a River Otter as having fun.