Hidden Wounds: How Hematomas Work in Chameleons

A hematoma is simple in principle: blood escapes from damaged vessels and pools inside tissue. The chemistry of that blood determines the colors seen in mammals. Fresh hemoglobin is red‑blue, biliverdin is green, bilirubin is yellow, and hemosiderin is brown‑black. As a mammalian bruise ages, these pigments shift, producing the familiar blue‑purple‑green‑yellow sequence.
Chameleons form the same hematoma. The same substances appear. The same biochemical breakdown occurs. But none of these colors ever reach the surface.
The reason is the chameleon's chromatophore system. Their skin contains a dense upper layer of melanophores, xanthophores, erythrophores, and iridophores. When trauma occurs, melanophores disperse instantly and flood the area with melanin. This creates a jet‑black surface patch that masks every underlying pigment. The green of biliverdin, the yellow of bilirubin, the brown‑black of hemosiderin — all remain hidden beneath the chromatophore layer.
What you see is not the hematoma.What you see is the melanophore reaction.
The real bruise, the pooled blood and its evolving pigments, stays invisible unless the skin is opened during necropsy. Only then does the internal hematoma reveal its true colors, identical to those in mammals but concealed by the chameleon's pigment machinery.
This is why chameleons "bruise black."The hematoma is there.The chemistry is the same.But the chromatophores override everything.