IGCSE Biology 0610: Adaptive Features of the Saharan Silver Ant

The Saharan silver ant (Cataglyphis bombycina) lives in the Sahara Desert and is one of the most heat-tolerant animals known. Unlike most desert animals, it forages for food above ground during the hottest part of the day, when the sand surface can reach temperatures above 60 degrees Celsius.

Some information about this ant is given below.

It has unusually long legs, which keep most of its body raised above the hot sand's surface.
Its body is covered in silvery hairs with a triangular cross-section, which reflect sunlight and radiate heat away from the body.
It can survive body temperatures that would kill most other desert animals, including the lizards that hunt it.

(a) State what is meant by the term adaptive feature. [1]

(b) Using the information given, describe two adaptive features of the Saharan silver ant and explain how each one helps the ant to survive in its habitat. [4]

(c) Suggest one advantage to the ant of foraging during the hottest part of the day rather than in the cooler early morning. [2]

Part (a): Definition of an adaptive feature

An adaptive feature is an inherited feature that helps an organism to survive and reproduce in its environment. It must be something the organism is born with (passed on through its genes), and it must give a real survival or reproductive advantage in the conditions the organism actually lives in.

Part (b): Two adaptive features of the Saharan silver ant

Long legs. By keeping most of the ant’s body well clear of the sand’s surface, long legs reduce the amount of heat transferred into the ant’s body by conduction from the ground, which can be far hotter than the air just a few centimetres above it. This helps the ant keep its body temperature within a survivable range even while standing on extremely hot sand.

Silvery, triangular hairs. These hairs reflect sunlight rather than absorbing it, and their shape helps the ant radiate absorbed heat back out to the surroundings. Both effects reduce the amount of heat energy that builds up in the ant’s body, again helping it survive the intense midday heat that would otherwise cause it to overheat.

Any two adaptive features described above, each linked clearly to a survival benefit, would gain full credit.

Part (c): Advantage of foraging at the hottest time of day

Most predators of the Saharan silver ant, such as desert lizards, cannot tolerate body temperatures anywhere near as high as the ant can. By foraging when the sand is at its hottest, the ant can search for food during a window of time when these predators are forced to shelter and are not active. This greatly reduces the ant’s risk of being caught and eaten while it is out in the open collecting food, even though it means tolerating extreme heat itself.

Final answers

(a) Adaptive feature: an inherited feature helping an organism survive and reproduce in its environment.
(b) Long legs raise the body above hot sand, reducing heat gained by conduction; silvery, triangular hairs reflect sunlight and radiate heat away, both reducing the risk of overheating.
(c) Foraging in the extreme midday heat lets the ant avoid its heat-sensitive predators, reducing the risk of predation.