"The question of size is a tricky one," says Jesus Rivas, a herpetologist and professor of biology at New Mexico Highlands University. Imagine if someone asked you, "What's the largest land mammal?" According to Rivas, you would "answer before hesitation" that it's the African savanna elephant.
"Nobody would start bellyaching as to how much taller giraffes are. Simply because when we mean size, mass is the determining factor," he says. "That is why I simply say anacondas are the largest snakes in the world, period."
OK, but how big do they get?
Exact measurements are hard to pin down. Green anacondas — and reticulated pythons — are incredibly strong beasts. Not only that, but a massive snake doesn't always react well to handling.
So, anybody who might want to stretch one out by hand and hold it up to an extra-long ruler sure has their work cut out for them. Rivas' book, "Anaconda: The Secret Life of the World's Largest Snake," contains some interesting anecdotes about this.
In one chapter, he describes a colleague who measured a full-grown anaconda at 18 feet (5.5 meters). To get this figure, the scientist took a piece of string, held it over the struggling reptile's back and then measured the string.
Later, Rivas himself measured the same anaconda using the exact same technique — and found the creature to be just 14 feet (4.3 meters) long. Simply by twisting its body around, the snake managed to yield two very different measurements.
Now that we have the lowdown on retics and green anacondas, let's take a closer look at some of their large cousins.