Cutaneous Water Acquisition of the Australian Thorny Devil (Moloch horridus)


Thorny Devil (Moloch horridus)

Photo By: Eric R. Pianka (need to get permission)

Page 1: About the Australian Thorny Devil:

~Habitat- most of arid inland Australia, geographic distribution corresponds more closey to the distribution of sandy and sandy loam soils than to any climatological field (Pianka)

~ Size- females, (80-110mm and 33-88.7 grams), are larger and stouter than males, (under 96mm and under 49 grams)

~Growth- females grow faster than males after the first year, they grow for 5 years

~Age- estimated to live for 20 years in the wild

~Diet- feed exclusivly on ants (25-45 ants/min.)

~Interesting anatomical features- thorns covering their body, false head, "scale hinges" to transport water (special emphasis on this

~Camouflage- used to hide from predators

~Predators- monitor lizards, birds

~Reproduction- eggs laid from mid Sept. through late Dec. average of 8 eggs/clutch.

Page 2: Bentley and Blumer and the Experiments They Used to Discover the Cutaneous Water Acquistion of the Thorny Devil (1962)

~Buxton claimed that the Thorny Devils had the "power of absorbing water through the skin after showers of rain." Bentley and Blumer thought this unlikely for a reptile living in arid deserts (brief explanation on water permeable skin and why this would be bad for an animal living in hot, dry conditions).

~Experiments: change in weight in hydrated and dehydrated thorny devils; dehydrated thorny devils gained weight when laying in the water even though they did not drink in the usual manner, mouth was opening and closing though while weight was being gained. When their mouths were taped shut, they did not gain any weight. Hydrated thorny devils did not gain a significant amoun of weight when laying in the water. A dehydrated thorny devil was then placed in water dyed with blue dye. Later the dye was found in the stomache despite the fact the the thorny devil never drank in the usual way.

~Concluded that there seemed to be a capillary system that allowed the water move across the skin and to the Thorny Devil's mouth. Thought that an ecological significance of this mechanism may be that animals with an impervious skin suitable to the desert can still use it to collect water.

Page 3: Morphology of the Thorny Devil's Scale Hinges that Allow Them to Cutaneously Acquire Water

~Two types of scales- large spines and smaller scales

~Reinterpretation of Bentley and Blumer's theory that water transports was casued by scale surface "channels"

~I have some great pictures of their scales at a microscopic level that I am hoping to get permission to use

~Will include a link to an awesome video that I found on Youtube, (still looking for the English version though)

Video of Thorny Devil Absorbing Water By Standing on Damp Sand

~The Thorny Devil uses its skin's super hydrophobic surface for channeling water between its scales

~Tiny capillaries between each scale that are used for channeling water

Page 4: Jaw Structure

~Jaw and mouth scale morphology

~Chemical factors in oral mucus have been hypothesized to facilitate water ingestion

~Screen of tissue suspended from the upper jaws

Page 5: Thorny Devil Water Acquistion Compared to That of Iguanidae

~Compare it to Iguanidae (Phrynosoma cornutum)

~Unrelated to each other

~Both can transport water over their skin albeit in different ways

~Pictures comparing their different scale types

Page 6: Andrew Parker and What the Thorny Devil Could Do For Science

~Andrew Parker- Biometric researcher at the Natual History Museum

~What is Biometrics

~What Parker has in mind for his Thorny Devil skin prototype

Page 7: References

(Not Properly Formatted Yet)

Bentley, P.J. and W.F.C. Blumer- Uptake of Water by the Lizard, Moloch horridus

Gans, Carl, R. Merlin, and W.F.C. Blumer- The Water-collecting Mechanism of Moloch horridus Re-examined

Mueller, Tom- Biometrics: Design by Nature

Pianka, R. Eric- Australia's Thorny Devil

Pianka, R. Eric and Helen Pianka- The Ecology of Moloch horridus (Lacertilia: Agamidae) in Western Australia

Sherbrooke, C. Wade- Rain-Drinking Behaviors of the Austrailian Thorny Devil (Sauria: Agamidae)

Sherbrooke, C. Wade et al.- Functional Morphology of Scale Hinges Used to Transport Water: Convergent Drinking Adaptations in Desert Lizards (Moloch horridus and Phrynosoma cornutum)

Withers, Philip- Cutaneous Water Acquistion by the Thorny Devil (Moloch horridus: Agamidae)