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18 Foot Alligator?

This photograph is currently doing the rounds on the Internet. It purportedly shows an 18 foot alligator caught on a construction site somewhere in Florida (the locations vary as frequently as the sender).

In fact, the very largest known American alligators are around 14.5 feet long - and that's very unusual! If this gator was 18 feet long... well, we might consider calling Guinness. How does this guy really measure up?

First, we have to assume the photograph is genuine - not always a valid assumption! Image manipulation is easy to hide, especially in a compressed JPEG photo, but let's give it the benefit of the doubt.

The best way to estimate his size is to compare tail length (which is mostly perpendicular to the photographer) and another known length. Let's take the guy standing behind him. Let's assume this guy is around 5 ft 8 inches tall - a fairly average height. The vertical red bar on the photo is my estimate of his total height (remember his lower legs are obscured by the gator's tail). What I've done is copied the bar and rotated it by 90 degrees, then moved it above the tail. Therefore, using this guy's estimated height we can estimate the alligator's tail length, which we know is approximately half of the total length.

As you can see, the length of the tail is around 7 to 7.5 feet in length. I won't argue the details. Double the tail length and we get 14 to 15 feet in length... maybe even slightly more (I'm being deliberately conservative). Not bad at all! Assuming the photograph is genuine, this is an impressively big alligator - one of the largest I've seen - but I think 18 feet is stretching it a little bit far!

Of course, if anyone who actually measured this alligator can contact me, I'd be interested to hear more.

UPDATE! I have now received confirmation from a reliable source that the alligator in the photo measured 13.5 feet long. The photograph was taken in Florida.

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