Ogopogo insights

It is interesting that two observations made this year, a swimming snake and a swimming muskrat, have prompted unexpected insights into our favourite lake monster, the ogopogo. I will show that if an ogopogo existed it would not look as it is always illustrated. Then I will explain why a family of travelling otters does look this way. 

A summary of the ogopogo is followed by a discussion of snakes and muskrats. 

An ogopogo is a supposed large serpentine monster reported in many of the lakes in British Columbia. Sightings have been made, perhaps every decade, since before European settlement. The ogopogo is now the darling of tourism organizations. So, I begin with a statue of it in Kelowna that appears to be an amalgam of some of the descriptions made on Okanagan Lake. As will be seen from my own pictures of its Kootenay Lake relative, the Kelowna representation is reasonably good, albeit stylized.

Here are some of my own pictures of the ogopogo from Kootenay Lake. First, a distant view where the sinuous loops and even some fins on the serpentine body are apparent.

I match a few of my other ogopogo pictures with historical observations from around Kootenay Lake collected by Tammy Hardwick (I Love Creston, 2011, p. 20).

“The monster…is ten feet long, six inches in diameter at the largest part and has a most hideous head.” Dec. 1900, George Graves and son, of Nelson

“We…were barely out of sight of Kaslo…a black head reared followed by at least one hump above the water some eight feet behind… We sat hypnotized until the ‘Ogopogo’ dived….” July 1937, Naomi Miller

“The visible part about twenty feet long, showed brownish in the sunlight, and the surface looked rough like a tree trunk with moss growing upon it.” April 1953, Two Boswell men

Now, biologists and naturalists have known for many decades that observations of an ogopogo were actually observations of a rapidly travelling family of otters. Indeed, my two observations turned out to be otter families. (All of which has not prevented the ogopogo from being promoted as a tourist attraction.) So, what else can possibly be said on the subject? Indeed, what possible insights could be gained into the ogopogo by watching a snake and a muskrat?

The ogopogo is often described and illustrated as being serpentine, so it is reasonable to ask how a snake moves through the water. It moves sinuous undulations along its body, but not in the way an ogopogo is presumed to do. The undulations in the ogopogo’s body are vertical, but a snake’s bends are horizontal. Only horizontal undulations can effectively press against the water and move the snake forward. If an ogopogo existed, it wouldn’t use the ineffective vertical undulations as a means of swimming. Here is a garter snake swimming by applying horizontal undulations.

But, why is the ogopogo always illustrated as if swimming with the ineffective vertical undulations? Or, more to the point, why do otters swim this way. Here is where the muskrat insights of yesterday come in. The swimming speed of a muskrat is capped by its hull speed — the speed at which the wavelength of its bow wave is equal to the length of its body. At this speed, the muskrat seems trapped between two wave crests. For it to swim faster would increase the wavelength causing the muskrat to endlessly swim up hill from the trough to the crest of the wave and this would take more power than the muskrat can exert. However, this speed limit, the hull speed, being caused by surface waves, is only applicable at the surface. The muskrat can move very much faster when travelling underwater. 

The same is true of any swimming animal: it can move faster underwater. When an otter chooses to move slowly, its whole body can be seen. Its speed over the water surface is similarly limited by its hull speed, in the otter’s case a bit over one metre per second.

But, when the otter wishes to travel a great distance quickly, as when swimming up the lake, it avoids the speed limit imposed at the surface by diving. Of course, it must keep returning to the surface where its noise pointing up can be interpreted as the ogopogo’s fins. The otter then dives again presenting us with the ogopogo’s vertical humps.

It is interesting to me that the reason we imagine a serpentine lake monster is that the otters in a family constantly dive so as to avoid the effective speed limit imposed by the waves they create while swimming at the surface. It is also interesting that, as far as I know, no one ever pointed out that an actual serpentine monster would not swim with vertical undulations in the way an ogopogo is always depicted as doing.

Of course, the legend remains good fun and even I made a pilgrimage to Kelowna’s statue of the ogopogo. Yet, I make no apologies to the British Columbia tourism industry when I close with a portrait of the real ogopogo.