Off the coast of Costa Rica, a shark has been caught that stands out due to its unusually bright orange colour. The more than two-metre-long nurse shark was discovered during a recreational fishing trip near Tortuguero National Park at a depth of 37 metres. Its striking appearance is due to an extremely rare pigment disorder.
Cause: Xanthochromism and albinism
Researchers believe the colour change was caused by xanthochromism, also known as xanthochroism. The animal lacks red pigment, resulting in excessive yellow or gold tones. In this case, it led to the intense orange skin. Such cases have never before been documented in cartilaginous fish like sharks, rays, or chimaeras in the Caribbean.
The nurse shark also exhibited signs of albinism: notably, its white eyes. Normally, nurse sharks have a brown colouration that helps them camouflage on the sandy seabed. The unusual colouration could, however, make the shark more visible to predators and thus more vulnerable.
“Further research is needed to determine whether genetic or environmental factors contribute to this rare pigment disorder in sharks,” the scientists explained.
Rare anomaly with scientific significance
Xanthochromism is extremely rare in the animal kingdom. So far, only isolated cases have been documented in fish, reptiles, and birds. The fact that it has now been recorded in a nurse shark in the Caribbean raises new questions about the genetic diversity of this shark species. While some scientists suspect that animals with this anomaly have lower survival chances, this discovery may challenge that assumption.
The cause is usually a genetic mutation, but environmental factors such as diet can also influence pigmentation. The find has therefore generated great interest in marine research and could provide new insights into the adaptability of cartilaginous fish in the long term.
