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Cryptid Petting Zoo
|Hiding with Schrödinger's cat|
A sea serpent is a supposed sea creature of great size, often the subject of sailors' yarns, but which also swims accidentally into the fringes of science. Reported from all seas, and sometimes backed up with photos of poor quality and bodies that wash up only to conveniently wash out again (or turn out to be merely basking sharks or whale blubber), the sea serpent is a myth that refuses to go away, and yet, with an ever-increasingly-explored ocean, refuses to come to the surface and be counted. In a way it represents cryptozoology itself—it's outside science, yet claims scientific respectability, ever shifting in outline and focus, yet always enticing those dreamers whose approach to science is not "is it true?" but "what if?". With such valiant, grandiose defenders of its name to speak for it, the serpent, real or not (on balance, probably not) will never gain a place at the high table of science without some solid evidence. And a good thing too—who'd want to sit down to dinner with a freaking great sea creature?
Other bodies of water
Lake monsters are similar to sea serpents, reported from the lacustrine regions of the world. Nessie and Mokele-mbembe are well known, as are the oddly-named Ogopogo of British Columbia, and Champ, who resides in Vermont, is thus probably one o' them dirty liberals. There are many more, and they usually have whimsical names. Iceland has the lagarfljotsormur (or Lagarfljóts worm). Manipogo, anyone? Morag? Hapyxelor? What the hey is a hapyxelor? Did somebody just pull letters out of a scrabble bag?
Reports of river monsters are even rarer, and a few orders of magnitude less likely. The White River Monster of Arkansas is the least obscure, and was emphatically not Bill Clinton going for a skinny dip.
Real aquatic snakes and monsters
Snakes of subfamily Hydrophiinae actually live in water, but are not by any means huge legendary sea monsters, although some have extremely toxic venom. As with many sea creatures, loss of habitat is a major concern.
There are mysterious and gigantic sea creatures living in our oceans but they are not snakes or serpents. The colossal squid (Mesonychoteuthis hamiltoni) is a huge creature long with sharp hooks on its tentacles which lives 1000-2000 metres under water near the Antarctic, and may grow more than 10 m long. Although parts were found in the 1920s, complete specimens were only found early in the 21th century. There are also gaps in knowledge of another large, deep water-dwelling cephalopod, the giant squid (Architeuthis dux) with scientists uncertain of their maximum length. Although known for centuries from sailors' stories and dead specimens, they were them not filmed in the wild until 2006
although, they had been filmed in the city as far back as 1985 guest staring on numerous episodes of the golden girls 
"Sea monsters" of a sort existed in the past, in the form of prehistoric marine reptiles, particularly the plesiosaurs, ichthyosaurs, and mosasaurs. Such animals became very large, with one specimen of Tylosaurus pembinensis measuring almost 43 feet in length. These reptiles, plesiosaurs and mosasaurs in particular, possessed many traits, such as long necks, fins, lizard-like skulls, and flippers, which are commonly associated with mythical sea serpents, and they were often depicted as resembling said creatures in early depictions made shortly after their discovery. While these creatures are often hypothesized by cryptozoologists to have survived into the modern day, providing an explanation for alleged "sightings," the fact is that these creatures are extinct, and have been since the K-T extinction event 65 million years ago.
- See the Wikipedia article on Cadborosaurus. for a strange tale of one that got away.
- "Of course some legends are just plain ridiculous, even to an open-minded cryptozoologist. Hapyxelor (or “Mussy”), the silver-green scourge of Muskrat Lake north of Ottawa, has three eyes, three ears, one big fin halfway down its back, two legs and a single, large, gleaming tooth in front. Clearly the mushroom-pickers who imagined this one never studied vertebrate anatomy or knew about the biological law of bilateral symmetry."
- ftp://ftp.fao.org/docrep/fao/009/y0870e/y0870e65.pdf Food and Agriculture Organization of the United Nations
- Colossal squid
- Colossal Squid Is No Monster, Study Finds, Live Science, May 10, 2010
- Giant Squid, Smithsonian Ocean Portal