Afrixalus uluguruensis at night (left) and day (right) showing starkly differing coloration. Reed frogs are some of Africa’s most diverse groups of frogs and as their name suggests, usually hang out on reeds overhanging ponds and ditches. A peculiarity of this group of frogs is that many of them don’t lay their eggs in water (like most frogs), but instead attach them to said reeds. Once the tadpoles are ready to hatch, they just drop into the water below! The reason for this strategy is most likely to avoid aquatic egg predators, a big risk for frogs (but check out this cool video of snakes feeding on such leave-bound eggs in the famous red-eyed tree frog in Central America: https://www.youtube.com/watch?v=dNHC4OciQJw).
The two biggest groups (or ‘genera’) of reed frogs are Hyperolius and Afrixalus. The latter are sometimes referred to as the “spiny reed frogs” due to their rough, sandpaper-like skin and both are fairly wide-spread across the African subcontinent. Besides their spiny skin, Afrixalus has one more peculiarity up its sleeve… as day breaks and they search for places to rest (most frogs are nocturnal), they dramatically change their colour with some going completely white! Although most (if not all) frogs are able to change color to some extent (usually limited to different shades or intensities of the same colour), reed frogs like this Afrixalus uluguruensis are literally like night and day!
Although this oddity is fairly well known, and other species of frogs do it too, surprisingly little is known about the exact function of this colour change. Dramatically paler day time colourations are often seen in those species that also rest in fairly exposed places and so it might serve as some sort of UV protection or to keep cool and prevent dehydration during the sunniest parts of the day, but these hypotheses are yet to be formally tested.
-Christoph Liedtke
The two biggest groups (or ‘genera’) of reed frogs are Hyperolius and Afrixalus. The latter are sometimes referred to as the “spiny reed frogs” due to their rough, sandpaper-like skin and both are fairly wide-spread across the African subcontinent. Besides their spiny skin, Afrixalus has one more peculiarity up its sleeve… as day breaks and they search for places to rest (most frogs are nocturnal), they dramatically change their colour with some going completely white! Although most (if not all) frogs are able to change color to some extent (usually limited to different shades or intensities of the same colour), reed frogs like this Afrixalus uluguruensis are literally like night and day!
Although this oddity is fairly well known, and other species of frogs do it too, surprisingly little is known about the exact function of this colour change. Dramatically paler day time colourations are often seen in those species that also rest in fairly exposed places and so it might serve as some sort of UV protection or to keep cool and prevent dehydration during the sunniest parts of the day, but these hypotheses are yet to be formally tested.
-Christoph Liedtke
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