Agama on Hot Sand

Explanation: These deserts of Mongolia and China get hot! We are looking at a toad-headed agama, whom we encountered in a previous EPOW episode, but this time focused on its adaptations to this harsh and arid environment.

This reptile is wonderfully adapted for these lands, here photographed in the Gobi Desert of southern Mongolia. It usually inhabits burrows during nights and during particularly hot days.

Note, in the main photo above, the stance of this lizard on the hot sand, using its unusually long toes and legs to raise above the surface. This provides the least contact surface with the hot ground, allowing air to circulate underneath the body.

Previously, we explored how color morphs of this species seem remarkably adapted to a variety of ground colors and patterns.

The head is very blunt and fortified with thick scales,
allowing it to burrow head-first into the desert sands.
(The red blotch on the side is a characteristic of the species.)

The eyes are also ringed by heavy scales that likely
provide protection from the sun's ultraviolet rays
and from sand grains during burrowing or as blown by the desert winds.

The skin folds might serve a function for increasing
surface area when the rare rains or fog might provide some evaporative cooling.

During rare rains, the lizard tilts forward, allowing rain to run down
its body into its mouth; perhaps the lateral fold along the side
of the body helps in this function.

Evolutionary studies of the suite of Phrynocephalus lizards suggest that the ancestor associated with sandy environments, and that during the mid-Miocene a rapid climate cooling led to the early species spreading widely through deserts of central Eurasia, where it is found today.

Information:
Solovyeva, EN, VS Lebedev, EA Dunayev, RA Nazaroy, AA Bannikova, J Che, RW Murphy, and NA Poyarkov. 2018. Cenozoic aridization in Central Eurasia shaped diversification of toad-headed agamas (Phrynocephalus; Agamidae, Reptilia). PeerJ 6:e4543.

EPOW - Ecology Picture of the Week