Movies: Size matters (just not to these filmmakers).

About half way through 2009 schlock-tacular Mega Shark versus Giant Octopus, my wife and I started questioning just how large the mega-shark, a recently unfrozen specimen of the 1.5 million year old megalodon species, was supposed to be. Sadly, we're never given enough shots of the eponymous cephalopod to even hazard a guess at his size. But the shark, or fragments thereof, appear in several shots with easily measured reference points.

First, of course, we know what species the beastie is supposed to be. We can start from there. Nobody knows just how big megalodon was. Because the monster was a shark, it's skeleton structure was made of cartilage and didn't preserve well over time. As a general rule, all that's left to us is the jaws and teeth. Surprisingly enough, that's really all scientists have needed to estimate megalodon's length. Here's the formula discovered by shark researcher Cliff Jeremiah in 2002:

Megalodon's total length, ft = (Root width of an upper anterior tooth, cm) x 4.5

Pretty simple. Applying that formula to the largest upper anterior megalodon tooth in the fossil record, you get an estimated length of 18.2 meters. That's a little over nine times the average height of an adult male human. Such a creature would weigh about 70 tons.

As luck would have it, one of the first reference point images viewers can use to scale the Mega Shark is a series of shots in which legendary singer and former Playboy model turned "actress" Deborah "Debbie" Gibson holds a tooth of the giant predator in her hands. The tooth shown in the film bears little resemblance to the triangular teeth of megalodon. Instead, it has one flat edge and one notched, curved edge. In the scene in question, Gibson – in the role of maverick ocean explorer Emma MacNeil – holds the tooth like a knife, the root of the tooth extending past the pinky-edge of her palm. Admittedly, there's no indication that this tooth is specifically an upper anterior tooth – though it did emerge from a whale corpse root side up, suggesting that we're at least looking at an upper tooth. Still, for purposes of estimation then, let's make the assumption.

Now we have to figure out how wide Deborah Gibson's palm is. Let's assume that Ms. Gibson is average – though purely in a statistically sense, there's naught average about the singer of "Shake Your Love" – and the size of her hand falls statistically dead center in the human female range of variation. This is unlikely, but for ease of calculation let's play along. The average length of a grown woman's hand, from longest fingertip to wrist is 18 cm. The fingers make up a little more than half that length, so let's ballpark a safe 8 cm for the length of Deborah Gibson's pinky-side palm edge. Now we apply the formula and end up with a total length for Mega Shark: 36 feet long, about 11 meters.

Mega Shark is actually kind of a runt, by megalodon standards.

Of course, there's an issue with this measurement. Previous to the scene in which MacNeil fondles the monster shark's tooth, the ever-nimble Mega Shark leaps into the air and chomps down on a low flying jet liner. Not just any jet liner: a jumbo jet that, as best as I can figure, is a Boeing 747. Depending on the model, Such a jet has a length of 70 meters.

In the following scene – widely held to be the flick's "money shot" – we see that Mega Shark is nearly three times longer than the plane. Let's be conservative and say 2.5 times as long.



So that actually gives us a shark 175 meters in length. That's a beast nearly 575 feet long. If you're not keeping all these numbers in your head, the tooth from such a shark, according to the Jeremiah formula would have to be 128 cm long, meaning the length of Debbie Gibson's palm would need to be a little over 4 ft long.

But wait, we're not done! Mega Shark gets even bigger.

The picture below is Mega Shark attacking a ship that's only ever identified as a US destroyer.

I'm pretty sure this particular class of destroyer exists solely in this movie. That said, the turrets seen above look a bit like the turrets on an old Fletcher-class destroyer. In the film, the ship fits comfortably in Mega Shark's bite radius. Let's assume that Mega Shark has the same basic proportions of megalodon, though its pretty clear that he quickly outgrew his megalodon status halfway through the flick. The bite radius of the largest megalodon on record is roughly a tenth of its overall length. This is a pretty rough estimate (hence the specific formula derived from tooth root width), but since we're measuring the length of an absurdly large animal that eats airplanes and destroyers for giggles, let's give ourselves the wiggle room. If this destroyer was similar to the Fletcher-class destroyer, then Mega Shark's bite radius needs to be about 40 ft to accommodate the entire vessel. It's overall length would then be a little greater than 400 ft, or about 122 meters. At this point in the film, Mega Shark is as long as 29-story building.

But wait – Mega Shark's got just a little bit further to grow.

In my favorite scene, Mega Shark attacks the Golden Gate Bridge. Why is unclear. Certainly the motorists on it hardly constitute a snack for the now titanic monster. However, it had been lured to the bay with the promise of a mate only to find the whole thing was a trap. Perhaps this bit of landmark vandalism was just a big "screw you" to the humans.

Regardless of the reason, the result is that Mega Shark bites cleanly through the entire 90 ft width of San Francisco's beloved span. Using the same rough calculation, Mega Shark reaches a full, majestic length of 900 ft, 274 meters. Coincidentally, he's about the length of one of the Golden Gate Bridge's towers.

If you've read this far, then you have officially spent more effort thinking about Mega Shark versus Giant Octopus than the filmmakers did.