Tetrapod Zoology

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Without doubt, one of the coolest living animals on the planet is the Komodo dragon Varanus komodoensis, a giant flesh-eating lizard that kills water buffalo, eats children, harbours noxious oral bacteria and is impervious to bullets (ok, I made that last bit up)…

Unknown to western science until 1912 (when it was ‘discovered’ by J. K. H. van Steyn van Hensbroek, and described in the same year by P. A. Ouwens), it reaches a maximum authenticated length of 3.5 m and can weigh about 250 kg (Steel 1996). In contrast to most other monitors, its legs and tail become proportionally short and stocky as it gets larger. As a juvenile it is an excellent climber; as an adult it can dig burrows, locate carcasses that are more than 10 km away, swim from island to island, and kill a water buffalo that weighs about 600 kg. Using teeth and claws, it disembowels, hamstrings and slashes its prey, and it may also shake prey to break the neck. Serrations on the posterior margins of the recurved teeth* end up housing rotting meat and an interesting assortment of over 50 bacteria that can cause septicaemia and death (despite claims that dragons are ‘infector killers’ it still seems most likely that any effects these bacteria have on prey are accidental) [see comments section for discussion of recently discovered venomosity].

* Anterior teeth are unserrated on both anterior and posterior carinae.

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While adult dragons today mostly eat mammals that have been introduced to Komodo, Rintja, Flores and the adjacent islands, fossils show that dragons previously lived alongside dwarf elephants (both Elephas and Stegodon), and it has even been argued that the dragon might be a specialised macropredatory giant that evolved to kill these (now extinct) endemic mammals (Diamond 1987). However, there were plenty of other small and mid-sized mammals that inhabited the same islands at the same time so ‘their diet was possibly more varied than just pygmy elephant’ (Mitchell 1987). Furthermore, the Komodo dragon almost certainly isn’t an example of island giantism: instead it apparently retains the large body size of a mainland ancestor (Gould & MacFadden 2004).

Dragons can be pugnacious beasts that might maim one another during combat; they also have cannibalistic tendencies. However, they also engage in appeasement behaviour, they tame quickly and appear to bond with humans, and ‘it is the opinion of many keepers that dragons may be among or the most intelligent of reptiles’ (Walsh et al. 2004, p. 12). As demonstrated by the awesome photos shown here, they can put their differences aside on at least some occasions, and it is well documented (although poorly known) that they will form ‘feeding scrums’ when attracted to a large carcass (Auffenberg 1981).

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Finally, the wild population of several thousand individuals is generally regarded as relatively stable: excepting Flores, the range of V. komodoensis was declared Komodo National Park in 1980. Some of the populations that occur on various of the smaller islands (such as Gili Motang and Flores) are regarded as particularly vulnerable to habitat loss and other threats, such as slash and burn farming (Ciofi et al. 1999).

Ok, so this was meant to be a picture of the day submission, but I suppose I got carried away. The pictures used here were supplied by Tim Isles (thanks Tim), but they’ve been used on the internet before: we lack data on who took the photographs and would be interested to get any news on this. Must revisit this species again. I previously wrote about play behaviour in Komodo dragons at ver 1, here. In fact I’m feeling a deficit of articles on big lizards in general. Great, now I have guilt. And didn’t I say I wasn’t going to publish anything today? Oh well, I’m sure you can all forgive me.

Refs – -

Auffenberg, W. 1981. The Behavioral Ecology of the Komodo Dragon. University of Florida Press, Gainesville.

Ciofi, C., Beaumont, M. A., Swingland, I. R. & Bruford, M. W. 1999. Genetic divergence and units for conservation in the Komodo dragon Varanus komodoensis. Proceedings of the Royal Society of London B 266, 2269-2274.

Diamond, J. 1987. Did Komodo dragons evolve to eat pygmy elephants? Nature 326, 832.

Gould, G. C. & MacFadden, B. J. 2004. Gigantism, dwarfism, and Cope’s rule: “nothing in evolution makes sense without a phylogeny”. Bulletin of the American Museum of Natural History 285, 219-237.

Mitchell, P. B. 1987. Here be Komodo dragons. Nature 329, 111.

Steel, R. 1996. Living Dragons. Blandford, London.

Walsh, T., Visser, G. & Lewis, R. 2004. Komodo Dragon Husbandry Manual of the AZA/SSP & EAZA/EEP: accessed online, 2005, at http://www.varanusweb.com/species_content/Kd-HDL-2004.pdf.

Comments

#1 Ed Yong
September 26, 2007

Some further Komodo coolness:

Contrary to popular belief, Komodo dragons (along with other monitor lizards and some iguanas) are actually venomous, according to a Nature paper from a couple of years back.

They can reproduce through parthenogenesis.
#2 Dave S.
September 26, 2007

I heard the komodo dragon has a slightly venomous bite. Not like the gila monster mind you, but venomous for a lizard. Any truth to that?
#3 Scott Belyea
September 26, 2007

“I believe they’re of the lizard family, aren’t they, Doctor?”

https://www.bobandray.com/listen.html
#4 Carl Zimmer
September 26, 2007

More cool Komodo trivia: they probably make venom.
#5 Mike Keesey
September 26, 2007

Furthermore, the Komodo dragon almost certainly isn’t an example of island giantism: instead it apparently retains the large body size of a mainland ancestor (Gould & MacFadden 2004).

Wow, really? I have to hunt down that ref sometime….
#6 Will Baird
September 26, 2007

We want a Big Beautiful Varanid Post, Darren!!!

Megalania! Nile Monitors! Their relations to the mosasaurs!

More More!
#7 Zach Miller
September 26, 2007

Yeah, is that mosasaur connection still stable? I keep hearing either monitors or snakes…
#8 John Scanlon, FCD
September 26, 2007

Alright Dazza, you’re forgiven. But didn’t you also mention squamates in the title of your SVPCA post? More of that to come, I hope!
While on giant goannas, my kids were watching Bindi Irwin’s show yesterday and I happened to see Steve (this was recorded a couple of years ago, obviously) cuddling a huge Varanus salvator that was living as a neighbourhood pet in some Asian city. Body like a barrel, meaty arms and hands that looked ridiculously short and wide, like flippers… and the lizard was pretty big too.

[from Darren: sorry, Houssaye's talk was the only squamate one. I've now changed the title to 'lepidosaurs'. And.... 'Dazza'? ]
#9 DDeden
September 26, 2007

Small komodos climb trees, are they egg and bird eaters primarily?

fresh article on venom in dry snakes, kraits and sea snakes
http://www.eurekalert.org/pub_releases/2007-09/bc-dtv092007.php
#10 sinuous_tanystropheus
September 26, 2007

Without doubt, one of the coolest living animals on the planet is the Komodo dragon Varanus komodoensis, a giant flesh-eating lizard that kills water buffalo, eats children, harbours noxious oral bacteria and is impervious to bullets (ok, I made that last bit up)…

Sadly, one can add poor judgment to the list. Imagine having a chance to eat Sharon Stone or her husband and opting for the husband….perhaps we were dealing with a specimen with poor eysight. Or perhaps he was trying to eliminate the competition. Analyzing animal behavior is SO subjective.

We want a Big Beautiful Varanid Post, Darren!!!

Megalania! Nile Monitors! Their relations to the mosasaurs!

More More!

I agree. More about Crocodile Monitors as well – highly underrated varanid. Do they really try to whip enemies in the eyes with their tails, or was the one encounter with the keeper just a coincidence?
#11 Nathan Myers
September 27, 2007

Speaking of island gigantism, let me direct your attention to …

http://www.qwantz.com/archive/001078.html

http://www.qwantz.com/archive/001079.html
#12 Sordes
September 27, 2007

Are you sure about the maximum weight of 250kg? Perhaps you have already read about the controverse weights for komodo dragons. 250 kg seems even for a very large one, which has eaten very much too high. The largest recorded specimen found by Auffenberg was 2,5m long and weighed only 54kg.
#13 Darren Naish
September 27, 2007

Dammit, why are published data on maximum sizes never reliable? I took the 250 kg from Steel’s Living Dragons (he doesn’t cite a source, but says that an adult in prime condition might get to 250 kg). Having checked other sources, I think you’re right that this is over the top. I’m also not sure about the 3.5 m (which I also took from Steel): Carwardine’s Guinness Book of Animal Records discusses the St Louis Zoological Gardens specimen (presented in 1928 by the Sultan of Bima), which in 1937 was 3.1 m long and weighed 166 kg. Captive individuals, of course, tend to be fatter than wild animals. So, thanks for pointing this out – I should have been more cautious.
#14 Steve Bodio
September 27, 2007

I believe the’venomous’ refers to the bacterial infections caused by their bites.
#15 Darren Naish
September 27, 2007

Steve: while all that stuff about 50 kinds of bacteria that cause septicaemia etc. is all still true (so far as I know), it turns out that the ‘rapid swelling, dizziness, localized disruption of blood clotting and shooting pain’ (Fry et al. 2005, p. 587) associated with the bites of Komodo dragons and other monitors in fact result from bioactive secretions (= venom). Venom toxins are now known to be produced by varanids, and also by some iguanians, so helodermatids are no longer the only venomous lizards: for more on this see Fry et al. (2005), and Carl Zimmer’s article linked to above.

Ref – -

Fry, B. G., Vidal, N., Norman, J. A., Vonk, F. J., Scheib, H., Ramjan, S. F. R., Kuruppu, S., Fung, K., Hedges, S. B., Richardson, M. K., Hodgson, W. C., Ignjatovic, V., Summerhayes, R. & Kochva, E. 2005. Early evolution of the venom system in lizards and snakes. Nature 439, 584-588.
#16 chris wemmer
September 27, 2007

Back in the early 60s, the herp keepers at the National Zoo (US) offered a dead muntjac (found that morning by conspiratorial ungulate keepers) to the Komodo dragon. (It was a really beeeeeg one). The zoo had just opened to the public and the dragon seized the muntes’ soft underbelly in its bacteria seething jaws and gave a mighty shake. This disembowelled the muntjac and created a Jackson Pollock like creation of rumen contents and blood on the glass front of the cage. (I don’t know why herp keepers don’t plan these things better.) A visitor saw the whole thing and reported it to the administration, and Ernest P. Walker (of Walker’s Mammals of the World fame) was on the scene in no time to discipline the keepers. This was told to me by the perpetrator himself, Lee Schmelzer, when I was a grad student and working as a seasonal keeper.
#17 Stevo Darkly
September 27, 2007

The Komodo dragon has always been one of my favorite animals.

I do believe they are members of the lizard family.

And wasn’t there some recent research showing that they don’t just have a septic bite, but are actually venomous?
#18 Homie Bear
September 28, 2007

And also, one once tried to eat Sharon Stone’s ex-husband.
#19 David Marjanovi?
September 28, 2007

I do believe they are members of the lizard family.

But so are the snakes and the mosasaurs, if “lizard family” is supposed to be a meaningful term. A family tree is shown in Carl Zimmer’s blog post; the snakes are marked “Serpentes”.

[from Darren: David David David... it's a joke, based on a comedy sketch. Don't stress about it ]
#20 David Marjanovi?
September 28, 2007

Ah. I’ve watched all of Blackadder, but almost nothing by Monty Python, let alone any other British comedy stuff…
#21 Jim
September 30, 2007

Did anyone know that komodo dragons are actually venomous?
#22 Jim
September 30, 2007

David: Bob and Ray are actually Americans. One of them (Bob, I think) is Chris Elliott’s father.
#23 Jim
September 30, 2007

Also, I’d like to be the first one to inform you all that komodo dragons are actually venomous.
#24 Lejon-Price-Jefferson
December 16, 2008

THOSE PIXS ARE SICK!!!
#25 Dewey
July 19, 2009

I’ve visited Komodo and Rinca islands in 1999 to see the ” Dragons” myself. Very worthwhile once you get past the mildly corrupt bureaucracy of the alleged national park rangers there , that tried to extort me to hire a guide to trek to see dragons that were in reality very nearby, and plentiful. There were juvenile Komodos in the trees of the park buildings. My impression was juveniles took to the trees not to eat birds and/or eggs, which is kinda foolish , but to escape adult Komodos who would most surely eat them. Odd that adult Fallow Deer were longing in the shade of the same trees in the public park complex. I ended up buying dried fish from the Sea Gypsy people at the little boat dock on Rinca to feed to the habituated Komodo that lived in the immediate area …a nice one, 3+ meters . A Photo Komodo. Got some extraordinary closeups of it…yellow tongue, jet black eyes, the teeth , scales, and especially the claws. I live in Wyoming and often photograph Grizzly Bears, who are mere teddy bears compared to Komodos.

One thing to add. On the north shore of the isle of Flores is a colony of rainbow colored Marine Iguanas that are every bit as large as Komodos. Visual stunners.
#26 David Marjanović
July 19, 2009

One thing to add. On the north shore of the isle of Flores is a colony of rainbow colored Marine Iguanas that are every bit as large as Komodos. Visual stunners.

If I had any, I’d bet some real money that these are Komodo dragons, and whoever told you they’re “goannas” ( = varanids) was Australian or had learned that word from Australians. Komodo dragons are known to occur on Flores.
#27 Hai~Ren
July 19, 2009

Dewey: Marine iguanas on Flores? Are you sure? Because that certainly is a very long way from the Galapagos. Any photos to show us?

By the way, the deer that you saw were rusa deer (Rusa timorensis).
#28 Hai~Ren
July 19, 2009

By the way, if those “marine iguanas” weren’t Komodo dragons, it’s likely that they were Malayan water monitors (Varanus salvator), which are said to be capable of reaching 3 metres in total length.
#29 David Marjanović
July 19, 2009

…while iguanas haven’t occurred in Asia since the, like, Oligocene or something, I forgot to add.
#30 varanidae
May 25, 2010

Great post, it’s nice to see varanids discussed here every now and then.

In case anyone’s particularly interested in learning more about this group, there is an open-access journal devoted exclusively to their biology entitled “Biawak” (a Malay and Indonesian word for “monitor lizard”). You can download the current issue and back issues for free at http://varanidae.org/biawak
#31 Krimeg
October 30, 2010

I presume Dewey was referring to an hydrosaurus species.

Monitor lizards are my favorites reptiles. Among those formers my favorite is varanus salvadorii, which beats Komodo both in awesomness and length, furthermore it looks somewhat like a quadrupedal Theropod !