Reptile & Amphibian Forums

ok, i am a frequent reader, but a first time poster here.

to give a little background on me and how i got into monitors, well, i'm one of those impulse savannah buyers that you read so much about, however about the same day i made my purchase i also did tons of research and set up a suitable habitat for my animal. i have now had him/her for over a year and he/she seems to be doing very well. i'll admit that i was wrong in buying my sav with no experience, but i didn't know any better at the time.

ever since i made my purchase i have been fascinated with the monitor species, not so much with the details of captivity, but with the behaviors and anatomy of the animals. my first question is about the olfactory senses of the species. i understand that the smell with their tongues and the vomeronasal organs, but they also have nasal passages. are they able to sense any smells out of their nose or not? and going along with this question are the air passages and food passages in the throat seperated? sort of like a snake being able to eat and breathe at the same time.

also if anybody happened to pick up the november issue of Natural History magazine they have a very interesting article on monitors and what's called Wallace's Line.

Hi,

From what I understand, monitors can smell through their nose, but it isn't as accurate as the jacobson's organ (the organ that the tongue transfers the scents to). You may notice your monitor's throat moving when you open its enclosure, before it starts to tongue flick. That gular pumping brings air in through the nose for smelling. My animals do this if I don't seem to be doing anything of real interest to them, but if I have anything in my hands they'll start tongue flicking.

As reptiles (outside of crocodilians) do not have a hard palate, the nostrils open into the mouth cavity rather than the throat. As a consequence, like snakes (which are very closely related to monitors, by the way), the opening of the windpipe (the glottis) is on the floor of the mouth, right behind the base of the tongue. As far as I know, monitors can't move it to one side of the mouth the way snakes can when swallowing huge objects.

I haven't read that article (not sure if Natural History magazine is available here) but am familiar with Wallace's line, which separates our fauna (Australasian) from South East Asian fauna. In a nutshell, they don't get marsupials, we don't get monkeys

However, if you get a chance, read up on Alfred Russell Wallace himself. He was a fascinating scientist and one of the unsung heroes of evolutionary theory and natural history. He came up with the same theory of evolution by natural selection as Darwin and ended up inspiring Darwin to publish his theory (which he had been sitting on for 20 years). They co-published a paper, but as Darwin had been mulling over the concept for 20 years, and presumably telling his colleagues about it during that time, he's the one whose name has been associated with the theory ever since.

DK Thanks!

you know i remmeber reading somewhere about Darwin not working alone and having some help, but i didn't know that it was this same Wallace. very interesting.

monitors really are amazing animals. their problem solving capabilities never cease to amaze me. for example i have a platform in my cage that has an opening on both sides. i drop a roach on the other side of the enclosure and zeus chases it across the cage the roach goes under the platform, zeus races over the top and beats it to the other side and gets a well deserved snack! incredible! and from what i've read their hunting and tracking skills in the wild are also incredible! anybody else have any interesting stories about monitor intelligence i'd be more than happy to hear them.

for those interested...
"Wallace's Line" refers to the change in wildlife occurring east of a line between Bali and Lombok and between Borneo and Sulawesi. Wallace developed his theories while discovering the change in ecology in this region dubbed "Wallacea" from greater Australasia.

A very interesting book for those interested in in fauna from the east is "The Malay Archipelago" Alfred Wallace, 1869.
-MQ

correct me if I am wrong, but I think the line correlates with deep ocean trenches, indicating that the two sides are on different tectonic plates (in other words, have been separated for a long time)

I'm not sure if the line lies on tectonic plates or not. it crosses between borneo and sulwesi. Wallace's line marks the eastern which limit of many animals having Southeast Asian affinities and the western limit of a fauna derived from Australia and New Guinea. In other words, large monitor species coexist with small mammals in the area near south east asia, however as you move closer to australia there are small populations of large monitors and also a small population of small mammals, along with a large population of small monitors. the idea presented is that small mammals and small monitors may be too similar as predators to coexist. this goes back to the intelligence of the monitor and the often over used term "mammalike".

Yes, and Alfred Russell Wallace also wrote a book on island life and a few others to-boot....Wallace's Line is mostly for mammals, but if you look at "Weber's Line", another boundary marker for species, this one birds and some reptiles, Varanids seem to fit better in their separation boundary = however there are varanids on both sides of this line, this line indicates australian forms vrs S.E. Asian forms and where they meet is in PNG. Some varanids came from Australia and went into PNG, while others went from Solomons-PNG into Australia...fun stuff. Dr. Ernst Mayr, an island zoologist who studies birds in these islands, who is in mid-90's now is writing a book on the phenomena and his travels 70 years ago!

cheers,
markb

There were actually two 'Wallace Lines'. Wallace originally placed his boundary to the northwest of Sulawesi (Celebes), but afterwards relocated it to the southeast of that. Wallace had unknowingly moved his line to a new position that accurately matches the plate tectonic history of the archipelago. The Australia and Eurasia plates collided fifteen million years ago, bringing two communities into contact that had been isolated from one another since the close of the Cretaceous (65 million years ago). During glacial maxima, Sulawesi was in contact with the Eurasian mainland, while a deep ocean trench separated Sulawesi from Southwest islands that WERE connected to Australia and New Guinea. After Wallace, researchers drew a number of other 'lines' in this area. There have been varied lines later drawn in this area - depending which animals were studied. Wallace used birds (especially parrots). The line actually shifts across the archipelago depending on whether the subject studied is or was birds, mammals, various reptiles or freshwater fish.

"...I believe the western part to be a separated portion of continental Asia while the eastern part is a fragmentary prolongation of a former west Pacific continent."
-Alfred Wallace

in situations where there are birds, mammals, freshwater fish and reptiles (like monitors), I'd be looking at the freshwater fish (and perhaps some of the mammals) as the true indicators of where the lines coordinate with the plates.

Freshwater fish that have no tolerance of saltwater are the best indicators, for they can't cross the saltwater barrier between islands. Some mammals (like our possums, cuscus etc) are also highly unlikely to cross those barriers, whereas birds can easily fly across and reptiles can swim or drift, surviving longer periods drifting on bits of debris than could a mammal (you never hear about the endemic land mammals of the Galapagos, do you).

HI Matt,

WOW, you're on a first name basis with Alfred! Sounds like you're very "up" on Wallace; who I personally look at as father of Origin of Species, although chronologically Charles Darwin and his uncle Erasmus Darwin and a few others came with first. I suppose it is my utter fascination with Wallacea region why I have a preference for Wallace's model and material he observed over Darwin's. Both are elegant as hell, and great men in their own respective spheres of furthering the 'thought of man' in understanding this world we live in, and one that both Darwin and Wallace would never recognize, except perhaps on some isolated Malay Archipelago isle....

Yes Sulawesi was once three separate isles smashed together, all from different tectonic plates; for a great look at how this region, geologically speaking got the way it is today, look at Stephen Oppenheimer's "Eden in the East" (1998) and Van Bemmelman "Geology of Indonesia" (1949; vol. 1-3) = an amazing chronology of this region for last million years and explains alot how animals and people, and varanids are where they are today, when and other marvels....

Thanks Matt,
markb

I share the same outlook on Wallace. At times I blame this also on my own fascination with the region, but when I read his works he is without a doubt one of the most brilliant Biologists and could have accomplished his works anywhere.

Thanks for sharing Mark.
-Matt Quinn