Many skeptics consider lake monsters to be purely exaggerations or misinterpretations of known and natural phenomena, or else fabrications and hoaxes. Most lake monsters have left no evidence of their existence besides alleged sightings and controversial photographs, and a large portion are therefore generally believed not to exist by conventionalzoologists and allied scientists. Misidentified sightings of seals, otters, deer, diving water birds, large fish such as giant sturgeons or wels catfish, logs, mirages, seiches, light distortion, crossing boat wakes, or unusual wave patterns have all been proposed to explain specific reports[citation needed]. Social scientists add that descriptions of these creatures vary over time with the values and mood of the local cultures, following the pattern of folk beliefs and not what would be expected if the reports were of actual encounters with real animals.[citation needed]
In Ben Radford and Joe Nickell's book Lake Monster Mysteries, the authors attribute a vast number of sightings to otter misidentifications: as Ed Grabianowski said,
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