The Known Suspects - A Short Answer

While great discussions have been had over the possible candidates for the Loch Ness animal, and I may go into greater detail about some of those theories in later posts, we are going to get the ball rolling with a single, and I hope definitive, statement:

Nessie is not an air-breather, which consequentially rules out everything other than fish or amphibians.

Even if the temperature of Loch Ness was warm enough to support reptiles (which it is not) and even if Plesiosaurs were not thoroughly extinct (which, unfortunately, they are) you couldn't hide a population of them in Loch Ness -- you couldn't even hide one.  As air-breathers, Plesiosaurs would continuously and regularly surface.  Their respiration would rule their behavior, and we'd have had our type specimen in hand long ago.  There are other problems with any form of giant reptile in Loch Ness, but the respiration obstacle alone ends that debate. The theory that the unidentified creatures in Loch Ness represent a relic population of surviving Plesiosaurs has been the romantic favorite for so many decades that many people will be disappointed by this.  But alas, this is rather irrefutable logic.  Nessie never was nor ever could have been a Plesiosaur.

The same logic applies to mammals and birds.  Extinction and known range aside, Hydrodamalis gigas, or Steller's Sea Cow might be a suitable candidate based on size and anatomical appearance, and could tolerate cold water, but runs into the same initial problem as a Plesiosaur: it would constantly be coming up for air, and too hard to overlook.  The same is true of any less exotic aquatic mammals, of which only whales grow large enough to account for the size of our mysterious denizen.  Even granted some form of giant aquatic reptile or mammal came equipped with snorkeling appendages that permitted it to sneak breaths without fully revealing itself at the surface, that would still place it at or near the surface on a constant and regular basis.  Such an animal would still be spotted regularly by fisherman, or any sufficiently patient monster hunters.  It would also have to regularly show up on sonar scans in mid-water, never far from it's source of oxygen.  The infrequency of such sightings tells us: we are not dealing with an air-breathing animal here.

A nod must be paid to the late F.W. Holiday, who espoused for many years his theory that Nessie was a giant aquatic worm.  His book The Great Orm of Loch Ness outlines this theory, as well as delving deep into the dragon mythology of ancient Europe, and remains a great read to this day.  The obstacle to entertaining the possibility of a giant invertebrate again comes down to Nessie's behavior, but in this case the rarest and most mysterious quirk in that observed behavior:  land sightings.  No invertebrate of Nessie's size could voluntarily leave the water, enjoy a stroll, and return to the water.  Like a giant jelly fish it would collapse under it's own weight if removed from the water.  Even Holiday acknowledged this flaw in his otherwise rather good theory.  As infrequent as land sightings may be, they have been a constant part of the historical tradition, and an irregular but definite portion of modern, recorded sightings (perhaps as many as two dozen instances since the 19th century).

Ultimately, it all comes down to behavior.  Nessie is a bottom dwelling, water breathing animal that spends very little time on the surface or in mid-water, although just enough to be spotted visually or by sonar on very rare occasions.  Its forays up from the the depths are most likely made along the sides of the Loch, to feed on the fish which are predominantly found along the sides, in shallower water above the underwater cliffs that precipitously drop off into the 750 foot abyss.  Such behavior is only consistent with a fish, or aquatic amphibian, which can extract all of it's needed oxygen directly from the water.

Yet as seldom as it happens, and for reasons known only to the animal itself, Nessie also leaves the water for apparently brief stretches, as observed most famously in the Spicer and Grant sightings of 1933 and 1934 respectively.  It may be said that this is nothing new:  it's a centuries old tradition among the Highlanders that the kelpie or water horse of Loch Ness comes ashore.  That's a key behavioral trait to take into account if we are distinguishing fish from amphibians.

My next post will be a picture essay which will on the one hand "deconstruct" one of the more famous photographs ever taken at Loch Ness, while further demonstrating why we should be thinking in terms of the Loch Ness Giant Salamander.