Big is Feared, Though Fake Elephant Ears Are Not for Hearing
Sensory Considerations in Chameleons
It is important to note that chameleons are practically deaf. Their auditory system is rudimentary, lacking external ear openings and tympanic membranes, and they rely primarily on vibration detection rather than true hearing. The large occipital lobes, which in profile resemble "elephant ears," do not participate in auditory processing in any sense. Instead, these lobes are visual structures, reinforcing the dominance of sight in chameleon biology. This anatomical reality underscores why visual signals play such a central role in communication, species recognition, and defense.
Occipital Flaps as Visual Signals
The occipital flaps of Calumma malthe are among the most striking cephalic ornaments in Malagasy chameleons. These structures are not ears, nor auditory organs, but visual amplifiers—serving both species recognition and sexual character displacement. In the dense mosaic of Maromizaha forest, where multiple chameleon species coexist, no two species share the same combination of head and body ornamentation. This ensures that females can easily identify their proper males, and that rival males display unmistakable signals in combat.
Calumma malthe: Long rostral horn, massive occipital flaps, no gular crest, dorsal crest interrupted, enlarged scales separated by three smaller ones.
Calumma brevicorne: Short horn, large occipital flaps (smaller than in C. malthe), no gular crest, continuous dorsal crest made of enlarged conical scales.
Calumma roaloko: Laterally flattened, rounded rostral soft flap; small occipital lobes fused above the neck.
Calumma fallax: Small rostral flap, no occipital flaps.
Brookesia superciliaris: Triangular superciliary peaks, gular beard of prominent conical scales.
Brookesia thieli: Superciliary peaks directed forward, very tiny gular conical scales.
Functions of the Flaps
Species and sex recognition: In Maromizaha, ornamentation is the passport to identity. Females can distinguish their males instantly, as no other species combines such features.
Aposematic display: When threatened, males evert their occipital flaps, enlarging the silhouette of the head. From a frontal view, the chameleon appears far larger than it truly is—an effective bluff against predators.
Male combat: In rival encounters, the flaps are deployed like shields, exaggerating size and dominance. The duel is often decided by who looks bigger, not who bites harder.
Fascination
The occipital flaps of Calumma malthe remind us that in evolution, big is feared even when big is illusion. These ornaments are not for hearing, but for seeing—and being seen. They transform a modest reptile into a forest giant in the eyes of rivals and mates, reinforcing the primacy of vision in chameleon biology.