Friday, November 30, 2012

CrocLog Podcast Episode 13

As promised, here's Episode 13 of the CrocLog Podcast. This is a special edition that focuses on the Christmas Croc Fest 2012, and we speak with one of the organisers Shawn Heflick who is hosting the event at his place in Florida. Some of you might know Shawn as one of the hosts of The Python Hunters which airs on Nat Geo Wild in the US and National Geographic Channel in the UK, and he's a bit of a croc fanatic.

Next up in December is our Christmas Special where we'll be answering a lot of questions from our listeners. It should be a fun time, so watch this space.

Click below for the podcast, plus links to where you can learn more about the Christmas Croc Fest 2012.

Wednesday, November 28, 2012

CrocLog Podcast Episode 12

It's nearly Christmas, and that can only mean not one, not two, but three CrocLog Podcast episodes over the next few weeks! Here's the first one, Episode 12, which is a nice long one to make up for the interval since the last one. Episode 13 will be coming shortly afterwards and is much shorter, where we'll be talking about an upcoming fund-raising event for crocodiles.

In this episode we interview Subir Chowfin about his work on gharials in the Corbett Tiger Reserve in India. Brandon and I also bring you up to date on the latest crocodile news, some interesting recent research on crocodile sense organs, Brandon updates us on crocodile attacks, and I try my best to keep the distracting noise in my microphone to a minimum. The wonders of modern audio technology.

Links to the podcast and a few of the stories below:

Friday, November 09, 2012

Crocodile skin is more sensitive than your fingertips

Crocodiles are covered in a scaly skin. And on each scale are tiny pressure receptors called ISOs, or "integumentary sense organs". These are very densely packed onto the scales around the jaws, but can also be found across the whole body. Well, except alligators and caimans. For reasons that aren't entirely clear, alligators and caimans have no ISOs on their body scales, only on the head.

It's been known for decades that ISOs are sensitive to pressure. They function as mechanoreceptors, which means that when they are deformed by pressure, they send a signal to the brain. Touch something with your fingertip - the texture you're feeling is the result of tiny deformations causing nerve signals to be sent to the brain which interprets them appropriately. As a result of this study, we know that the pressure-sensitive ISO organs on the head and jaws of crocodiles are so good at detecting pressure changes, they are even more sensitive than human fingertips. That's pretty darn impressive. Earlier work suggested that ISOs served to detect pressure changes at the water's surface, but this latest study proves they're a lot more versatile than that. They can detect a wide variety of touch sensations, pressure changes, and vibrations. Everything from delicately manipulating hatchlings to detecting minute pressure changes created by fish swimming past their jaws in the water. And more. We're working on one particular study at the moment that has just had a lot of light shed on it by this news.

Impressively, the study also clearly shows that the ISOs on the body also function as mechanoreceptors. The feet in particular are very sensitive, and could detect pressure changes in the water (and certainly touch). I once described the crocodile as being surrounded by a pressure sensitive net, so it's very cool to see the science behind it detailed so thoroughly and effectively.

I strongly recommend that you read the full paper at the Journal of Experimental Biology. There are some very cool diagrams of nerve networks, and it will really give you an appreciation for just how remarkable the ISO system is for crocodiles.

Thursday, November 08, 2012

How to save Orinoco crocodiles

Orinoco crocodile, Photo by Roger Manrique

The Orinoco crocodile, Crocodylus intermedius, is a Critically Endangered species found only in restricted areas of Colombia and Venezuela. It's one of a handful of croc species that are in serious trouble right now, but there are ways in which you can make a difference. The easiest of these is to raise funds to support an active and effective conservation and management program, and right now you're in luck because the Christmas Croc Fest 2012 is raising money for such an program. We'll be highlighting more ways in which you can make a difference to crocodilian conservation efforts around the world in the coming months, so right now it's the turn of C. intermedius to bask in the spotlight of concern. I'll hand you over to the organising committee for the Croc Fest after the break, and they'll tell you exactly why you need to attend.

Monday, September 03, 2012

Can crocodiles predict earthquakes?

Things have been a little quiet on the Croc Blog of late, so to shake things up here's a curious news item from the Philippines. Apparently seconds before the strong magnitude 7.7 earthquake tremor in East Samar recently, Lolong reacted violently while resting in his enclosure. The news agency suggests that Lolong was able to predict the earthquake, although with seconds to spare I doubt he'll be making that role official. But what's going on? Can crocodiles really predict earthquakes?

Well there is a more reasonable explanation. Lolong was simply responding to low frequency vibrations transmitted through the ground immediately prior to the earthquake. These are termed P waves, or compressional waves, and it's often difficult for humans to detect these. Crocodiles, however, are experts at detecting changes in pressure and vibrations, so it's very likely that Lolong was feeling the P waves produced at the beginning of the tremor. S waves, or shear waves, tend to follow P waves and are the ones that do the damage, and the ones that we are most aware of.

Why did Lolong react to the P waves? We know that crocodiles are highly sensitive to pressure waves, senses that are used not only to detect potential prey but also for social communication. Thunder and vibrations transmitted through the ground frequently trigger a territorial response from large male crocodiles (and a fear, distress response from small, subordinate crocodiles), and an earthquake's P wave would only heighten that response. There wouldn't be many crocodiles capable of giving Lolong a serious territorial challenge, but the P wave of an impending earthquake would very likely feel like one.

Did giant croc 'Lolong' predict 7.6 quake? | ABS-CBN News

Image credit:

Friday, August 24, 2012

CrocLog Podcast Episode 11

After a possibly record-breaking interval of three months, Episode 11 of the CrocLog Podcast is finally available. As usual the delay is down to basically being very busy, but while Brandon was visiting me in Darwin last month we sat down and discussed some of the latest croc news.

We couldn't line up our interviewee for this episode, so they will be appearing in the next one instead. So instead Brandon and I discuss the recent CSG Working Meeting in Manila, a few more ongoing dramas with Lolong, taking tissue samples from Nile crocodiles while diving with them, giant prehistoric crocodiles, tiny extant pygmy crocodiles, and some recent crocodile attack incidents.

Links to the podcast and a few of the stories below:

Saturday, July 14, 2012

Diving with Nile Crocodiles

Yes, that's me sneaking up on the tail of a nearly 4.5 m Nile crocodile (Crocodylus niloticus) in the Okavango Delta recently [photo credit Brad Bestelink, Natural History Film Unit]. We called this crocodile "Number 9" because that's his data ID. It also has a nice ring to it. If you want to see what happens next, you'll have to tune into 60 Minutes (Australia) which airs this Sunday 15 July at 8pm (EST) on Channel Nine. This is part of a research project that we're running in Botswana, the details of which I'll go into in a future post. There is a reason behind getting so close to this crocodile underwater, other than simply getting some amazing film footage courtesy of the Natural History Film Unit.

Here's the 60 Minutes promo for the story. They dusted off Mr Dramatic Voice-over Man just for the occasion. Yes I know, it's a promo, it has to look like a Michael Bay movie, but I'm fairly sure the actual story itself will be more balanced. If not I shall send Smaug across to deal with them.

Liz Hayes (reporter) also posted a blog about her experiences with us in Botswana which you can read here, and there's a photo gallery here

Finally, I'm going to be the web guest in the Chat Room after the show at 9pm, so come along and ask some questions.

[update] You can see the story online now here. It's a shame they didn't spend more time on the actual research project and why we were diving, but overall I think they did a pretty decent job.

Saturday, June 23, 2012

Lolong officially the world's largest crocodile in captivity

Back in November 2011 I visited Bunawan in the Philippines to provide independent verification for the length of Lolong, a reportedly "6.4 m" saltwater crocodile (Crocodylus porosus) which had been captured in early September. I was asked to do this by Natural History New Zealand and National Geographic for several reasons, one of which is because I'm quite skeptical about reports of giant crocodiles. It was clear from the photographs and footage that Lolong was a large crocodile, but actually putting a tape measure against it was going to be the ultimate test.

In front of the assembled news media, several hundred visitors, local officials, members of the Palawan Wildlife Rescue and Conservation Center (PWRCC), Protected Areas and Wildlife Bureau (PAWB) and others, I was filmed measuring Lolong accurately using two different methods. The result of that filming will appear in a National Geographic documentary to be aired in the fairly near future, although I don't know the precise date unfortunately. Animal Planet has already aired a documentary about Lolong which they filmed after ours, but the Nat Geo show will show the actual official measurement.

In the meantime, Guinness World Records have accepted my measurement and the evidence provided by National Geographic, and declared Lolong the largest crocodile in captivity at 6.17 m (20.24 ft, or approximately 20 ft 3 in). Here's a photograph of the certificate to prove it:

Saturday, May 05, 2012

CrocLog Podcast - Episode 10

Episode 10 of the CrocLog Podcast is here at last. It's quite a long one though, so hopefully worth the wait. We're hoping to make future episodes a little shorter, but more frequent.

This time we interview the great Rom Whitaker, who has long been an inspiration for many of us, about some of his work in India with the Madras Crocodile Bank. Honestly we could have spoken with Rom for several hours, but maybe we'll do a follow up later. We also talk about recent news stories from April including crocodile bite forces, Cambodia selling off its National Parks to the highest bidder, American crocodile recovery in Florida, gharial recovery in Corbett Tiger Reserve, and more elelphant and croc interactions. Brandon updates us on some recent crocodile attack statistics, and we chat about the airing of the show Swimming with Crocodiles and a few behind the scenes tidbits.

Below you'll find links to the podcast and the main stories.

Wednesday, April 04, 2012

How hard can giant crocodiles bite?

A recent paper published in the journal PLos ONE called "Insights into the Ecology and Evolutionary Success of Crocodilians Revealed through Bite-Force and Tooth-Pressure Experimentation" presents the results of a study that was started over a decade ago measuring and comparing the bite force of different crocodilian species. I've been waiting for this to appear for years (I can almost say decades!) as I was superficially involved in the Australian work including catching wild C. johnstoni that were used. I'd also designed a very low-budget bite force meter and measured C. porosus bite force prior to this, and obtained the measure of 3,800 lbs with a 15.1 ft (4.6 m) captive saltie housed at Crocodylus Park which came in pretty close to the more accurate measurement obtained for this paper. So we've known for a while that these kinds of forces were normal for large crocodiles.

But one of the most interesting, and unexpected findings of this work was that bite force isn't dictated by jaw size and shape significantly. It plays a role, but there's no clear pattern. What does influence bite force primarily is body mass (and therefore size). That shouldn't be surprising - the bigger the croc, the harder it bites. But slender-snouted species like C. johnstoni can put the bite on as well as C. porosus can at similar sizes, which is a very cool finding. Gharials let the longirostrine side down a little, with a lower bite force relative to body mass, but they compensate for having a very specialised jaw design and also by being extremely cool.

Of course one of the reasons I've been waiting for this paper is to find out the relationship between body size (or mass in this case) and bite force with a good-sized dataset. With that information, we can start to ask some interesting speculative questions. For example, how much bite force could the world's largest crocodile generate? Let's try this with Lolong shall we? The equation used is as follows:

(Y(force, N) = 29.632x(body mass, kg)+569.35

So Lolong's mass is 1,075 kg, which means his bite force is estimated at 32423.75 Newtons, or 7289.1 lbs (about 3.3 tonnes of force!). Wow.

But what about Deinosuchus riograndensis, at an estimated 11 metres (36 feet) and therefore one of the largest crocs that has ever lived? Using figures for living crocs, his body mass is estimated at 3,450 kg, and therefore his bite force could have been a staggering 102,803 Newtons (23,102 lbs) which is 10.5 tonnes of bite pressure. Holy cow! No wonder these guys were capable of snacking on dinosaurs.

Thursday, February 16, 2012

Swimming with Crocodiles

If you're in the UK, tune in to BBC2 this Sunday 19 February at 9pm (after Top Gear) for Swimming with Crocodiles. Yes, that title is accurate. I travel to Botswana with UK adventurer Ben Fogle and we end up diving with some very large, wild Nile crocodiles in the Okavango. The first one I encounter ends up giving all of us quite a scare, because it comes to investigate us rather than the other way around. But the purpose behind doing this is not only to investigate the diving technique pioneered by Brad Bestelink and Andy Crawford, but also to learn a lot more about the behaviour and sensory abilities of crocodiles underwater. There's no better way of appreciating that than by entering their realm. It's one of the most remarkable projects I've ever been involved in.

For the second episode, which airs on 26 February, we investigate whether the same can be done with saltwater crocodiles here in Australia.

Monday, February 13, 2012

CrocLog Podcast - Episode 9

Episode 9 of the CrocLog Podcast is here. Brandon was having some quality issues with his mic but I managed to make it sound almost normal. That should be fixed for next time.

Brandon revisits Cherie and Vince Rose of ACES (American Crocodile Education Sanctuary) to get an update on their uphill battle working on American crocodiles in Belize, we discuss the latest news stories including another potential new species, one of the oldest “modern croc” fossils ever found, finding crocodiles where you don’t expect to find them, the recent spate of crocodile attacks, and a discussion of a TV show where they try and noose a large Nile crocodile underwater.

Below you'll find links to the podcast and the main stories.

Tuesday, February 07, 2012

Touch of the Blue Crocodile

There's a new feature-length crocodile documentary on its way called "Touch of the Blue Crocodile". I've seen the trailer, which you can view after the break below, and it looks excellent. The film-makers play on the traditional fear that many people feel about crocodiles, and then they turn it completely on its head. It encapsulates the issues surrounding wild crocodiles living increasingly close to people, and confronts you with two very different sides to the argument. I particularly like the way it gets back to the notion of the crocodile as a mythical creature, with all the benefits and drawbacks that entails.

After the jump, the trailer and more about the documentary.