Leaping lizards!

May 15, 2014 • 11:53 am

Before someone corrects me, yes, I know that crocodiles aren’t lizards (they’re in different orders of reptiles), but the title of the post will resonate with you if you’re “of a certain age,” as they say.

TheYouTube notes give the location, and I’m not sure how I feel about keeping crocs in captivity and having them do tricks for people. I suspect, though, that, being sedentary, they don’t suffer from this as much as do beluga whales, porpoises, or orcas:

Thanks to http://www.crocosauruscove.com in Darwin, Australia. You can feed crocodiles, swim with crocodiles, and get really up close to them. Feeding them using a fishing rod is a really unique experience, as you can see they can jump completely out of the water.

The behavior is surprising, though. Given that they probably never do this in nature, it must be something of a spandrel (a byproduct of another evolved behavior), supported by the observation that they seem to leap by making swimming motions.

Further notes by Greg Mayer

These are saltwater crocodiles (Crocodylus porosus) at Crocosaurus Cove, a reptile zoo in Darwin, Northern Territory. “Salties” are known for their ability to jump vertically, but this is the only film in which I’ve seen them completely clear the water. (There’s a possibility that the crocodile whose tail left the water may have been hanging on to a “fishing” line, and thus been partially pulled up, but although no segment shows both the head and the tail out of water simultaneously, I think they are actually leaving the water on their own.) The usual context for seeing these vertical leaps by salties are by wild crocodiles which have become habituated to the presence of tour boats and the food proffered from them.

"Brutus", the one-armed saltwater crocodile, jumping for tourists on the Adelaide River, Northern Territory. Photo from Courier Mail, Brisbane.
“Brutus”, the one-armed saltwater crocodile, jumping for tourists on the Adelaide River, Northern Territory. Photo from Courier Mail, Brisbane.

“Brutus”, said to be 5.5 m long,  is much larger than the crocs in the film, and I don’t think he would be able to leave the water completely. (You can judge the size of a saltie by the shape of the head– they start out narrow, and get relatively broader and more massive as they get bigger.)

The way the crocs jump is by using their standard swimming motion: lateral undulation, legs tucked in, with the tail providing most of the propulsion. In jumping, they swim straight up (instead of more horizontally), and develop enough head of steam to partially or entirely break the water surface. Jerry supposes that they never do this in nature, but I’m not so sure. A number of crocodilians are known to skulk around waterbird rookeries, eating the birds that may fall out of the trees into the water, and there’s no reason to think they wouldn’t jump up to grab a bird as well. Here’s a photo of a Nile crocodile going after a grey heron from the National Geographic photo contest. (But note: the water that this Nile croc is in is much shallower, and it may be pushing off with its feet rather than its tail.)

Nile crocodile jumping for grey heron. Photo from Adelaide Advertiser.
Nile crocodile jumping for grey heron. Photo from Adelaide Advertiser.

h/t: Matthew Cobb

15 thoughts on “Leaping lizards!

  1. Ichthyologist friend told of running gill nets leaning over the side of the boat in areas where tourists feeding of crocs occurs. Fortunately he did not get eaten.

  2. The meat appears to be on metal hooks, and at least one croc in the film broke the string and presumably swallowed the hook.

    IIRC, I’ve seen video footage of amazonian crocodilians leaping vertically like this to get young birds, by knocking them out of low nests.

  3. Habituation in crocodilians is a sad situation. These crocs can never be returned to the wild, because they have lost all fear of man (not that salties had much to begin with!). I have had to deal with habituated alligators here in South Carolina. Some tourists feed the gators until they become used to begging and then they get demanding! Pretty soon a poodle disappears and the gator is destroyed or relocated. We caught a lot of gators because of human habituation. Sad!

  4. I just saw an interesting National Geographic special on these crocodiles living in the wilds of northern Australia. In it, there was discussion and video of a large (5.5 metre) crocodile jumping 2.5 metres out of the water to catch bats. The narrator says the crocodile uses his tail to propel himself out of the water, and if you watch the footage you can see the crocodile’s legs tucked and his body undulating side to side. The relevant footage starts at 47:40: http://goo.gl/XpB2uu

  5. When I was in Darwin once a tour guide told us that at one point they had people bungee jumping from a disused harbour crane – until someone realised it was fly fishing for crocs. Possibly apocryphal but it was a good story.

  6. There’s a possibility that the crocodile whose tail left the water may have been hanging on to a “fishing” line, and thus been partially pulled up

    That is probably not possible. The crocodile would have to grab the bait while still moving upward and the person holding the pole would have to do significant work pulling the crocodile upwards before the crocodile reached the highest point. Any pulling after the highest point (which is probably when the crocodile closes its mouth) could slow descent, but not help with height.

    1. I think it’s safe to say that the crocs are able to leap out of the water to such heights. We can see from the video that two crocs made it to the same height, with only one latching unto the bait.

  7. I’ve seen Brutus up close and personal. A couple of years ago, Dr Wifey and I went on one of the Adelaide River jumping croc tours (I have no interest in seeing captives) and I can confirm that a 4+ metre-long adult can easily haul its entire body out of the water vertically for a treat by threshing its tail laterally – the normal swimming motion. Along with the impressive hydrobatics, there’s a very loud, very deep “snap” when the crocs close on a treat (and especially when they miss) – you can hear up close just how much force these creatures can generate with their jaws.

    The treats – chunks of feral water buffalo – weren’t on hooks; they were tied loosely with string. They’re so small that there’s no danger of harming the crocs’ normal feeding behaviour – it’d take a heck of a lot of buffalo chunks to get these guys to stop hunting actual buffaloes, water birds, ‘roos, river turtles (which, when munched, make a distinctive “POP” that can be heard miles away), occasional stray stock/pets and very occasional stray humans.

    Anyway, after a little cruise and a few “jumps”, the boat operator spotted Brutus sunning himself on a bank and parked the boat next to him in the mud – close enough to count the scales on his head. I can tell you, it’s a very sobering experience looking into the eye of a crocodile who’s longer than the boat you’re sitting in. As for the missing arm? To my mind that makes Brutus even more of a badass. You don’t get to 5.5m long in the Adelaide River without learning how to look after yourself.

    As for whether the behaviour is human-induced or natural, I don’t know, but I find it quite plausible that a hungry salty could have a go at something like a nest overhanging the river or an animal up a steep bank. The natural expression of the jumping behaviour mightn’t have been to jump exactly vertically but it wouldn’t take much to induce an animal used to jumping diagonally to vary their angle a bit.

  8. Crocs scare the crap out of me. I wouldn’t want to be in a vessel that was open enough for pieces of me to be snapped off!

    1. The sides of our boat were railed off nicely and crocs are quite focused on the raw buffalo chunks on offer, but the tour operators issued frequent reminders to keep all extremities inside the boat.

      Ours also said, more than once, “If you fall or get dragged into the river, please be aware that noone is coming to get you because you will be food.”

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