Albinism in Sharks

The relative darkness or lightness of a given shark species may vary enormously among individuals. A few species of sharks, such as the Dusky Smoothhound (Mustelus canis) can gradually change their color after moving from one habitat to another. Other species, such as the Blacktip Shark (Carcharhinus limbatus), may temporarily lose virtually all their pigmentation during "whitings", which are poorly understood blooms of shelled protozoans called "coccolithophores". But true albinos resulting from a blocked gene crucial to pigment formation seem to be very rare among sharks. Below is a list of all shark species in which partial or full albinism is known to date:

Broadnose Sevengill Shark (Notorhynchus cepedianus) - partial
Zebra Shark (Stegostoma varium) - partial
Tawny Nurse Shark (Nebrius ferigineus)
Basking Shark (Cetorhinus maximus) - 2 Cases
White Shark (Carcharodon carcharias)
Grey Smoothhound (Mustelus californicus) - 2 Cases
Leopard Shark (Triakis semifasciata)
Tiger Shark (Galeocerdo cuvier) - embryo
Java Shark (Carcharhinus amboinensis)
Scalloped Hammerhead Shark (Sphyrna lewini)

Why is albinism so rare among sharks? Probably because being snow white makes them highly visible to both prey and predators, so it is unlikely they would long survive. Indeed, most albinistic shark specimens are young individuals. But a few such as the Zebra Shark case listed above, which was 6 feet (1.85 metres) long were quite large and may have been reproductively mature. Yet, if shark pigmentation patterns play a role in courtship signaling and other agonistic displays, it seems unlikely that an albino shark would compete effectively against 'normally' pigmented members of their own species.

 

ReefQuest Centre for Shark Research
Text and illustrations R. Aidan Martin
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