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Sea “Serpent” or Something Else? The Enduring Enigma of Mammalian Sea Monsters

Stories of sea serpents and water monsters are nearly as old as time. They are certainly as old, it can be said, as the earliest seafaring voyages, when humankind took to the waves, and returned with stories of large creatures from the depths that they could not explain.

Sightings of such creatures, most often partially obscured from view by the ocean water, became the stuff of myth and legend. However, with the passing of time, many of those denizens of the deep that had once been dubbed “serpents” were revealed to be other things: various kinds of whales or other mammals, and even giant squid are all among the known sources for such reports.

Occasionally, there are more compelling reports of unidentified, long-necked creatures seen in our oceans. Edmund Gustavus Bloomfield Meade-Waldo, a respected ornithologist (and a man with the perfect “Bond Villain Name” if ever there was one), observed such a creature while accompanying James Lindsay, 26th Earl of Crawford, and fellow respected naturalist Michael John Nicoll aboard the sailing vessel Valhalla in the winter of 1905. Despite its outwardly serpentine appearance, the observers felt that the creature’s movements and other behaviors indicated that it was some kind of mammal, rather than being a literal “serpent” of the seas.

On account of such reports, I have long been fascinated with the idea of unidentified mammals in our oceans, which might nonetheless qualify as suspects in the broader “sea serpent” mystery. One of my readers, Jesse, reached out some time ago to share such a story: in 2018, he and a friend were engaged in some recreational fishing off the coast of Miami. His companion, a commercial fisherman by trade, was well versed in the varieties of aquatic wildlife along the Florida coast.

The pair had walked down a pathway toward the mouth of a canal near Old Cutler and 57th, Jesse says. He recalled that there had been a ski boat on its way out of the marina nearby; however, in the wake left by this boat was something very unusual: Jesse describes it as having been an “extremely large something.”

The creature, Jesse said, resembled a very large seal or some similar animal. As he noted in his email, seals aren’t known for hanging around Miami beaches (although I’ll have more to say on that in a moment). Jesse explained that this large animal was certainly not a manatee, and was between 9-12 feet long “but not nearly as big in the midsection as a manatee and it was very agile.”

The fishermen observed the animal following the boat out of the marina as it “porpoised up and down,” locomotion which Jesse described as a movement beginning with the head emerging out of the water, then the body behind it.

Jesse’s friend, having been familiar with all the animals normally seen in the area, was shocked by this large creature and its movement. “We watched it swim from far away, then right by us and out to the ocean,” Jesse recalled. The entire observation lasted between 45 seconds and one minute.’

“I have no clue what it could be and have never seen anything like it,” he said. So what was this mysterious animal that Jesse observed?

One possibility could be sea otters, groups of which are commonly seen swimming and foraging around the Morrow Bay area. However, Jesse’s description of it being a large animal would appear to conflict with the sea otter hypothesis; this fact is made all the more interesting by Jesse likening it more specifically to a seal in appearance… because while he is correct that seals don’t exist in the Miami area today, this wasn’t always the case.

As recently as 1952 (or even 1956, according to some sources) a large variety of equatorial seal known as the Caribbean monk seal did still exist. These creatures could grow up to eight feet in length, and weighing as much as 600 lbs, making them a much better contender for Jesse’s monster.

The problem, however, is that they are believed to be extinct: the last known sighting of one of the creatures in the wild having been at the western Caribbean reef of Serranilla Bank, located between Jamaica and Nicaragua. Although more than 550 miles south of Miami and on the opposite side of Cuba, this is not a particularly great distance geographically speaking.

Even more compelling, in 2016 a group of archaeologists reported the discovery of a Caribbean monk seal tooth recovered from a dig site at Lake Worth, Texas. The discovery, while unique, is not unprecedented: sightings of the creatures on the U.S. mainland date to as recently as 1922.

Monk seals in captivity at the New York Aquarium, circa 1910 (public domain).

Although Caribbean monk seals are believed to have died out, we must recognize that many times in the past there have been instances where animals thought to have been lost to extinction have turned up again; the most notable is, of course, the rediscovery of the coelacanth off the coast of Africa in 1938. Other hopeful contenders include the Tasmanian Thylacine and a host of other animals believed to be extinct or critically-endangered in various parts of the world.

Nonetheless, sightings the likes of Jesse’s does give us hope for the survival of some of these creatures. It may well turn out to be that a few Caribbean monk seals have survived, and are still “porpoising” along in various regions of our equatorial waterways… which would present a splendid opportunity for rediscovery for conservationists and naturalists alike.


Micah Hanks is a writer, podcaster, and researcher whose interests cover a variety of subjects. His areas of focus include history, science, philosophy, current events, cultural studies, technology, unexplained phenomena, and ways the future of humankind may be influenced by science and innovation in the coming decades. In addition to writing, Micah hosts the Middle Theory and Gralien Report podcasts.
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