Observations of skin color aberrations in four shark species off the coast of southern California, USA

Abstract

Skin color aberrations are naturally occurring abnormal pigment patterns that are generally rare among chondrichthyans. In this study, we highlight different skin color aberrations from observations of four shark species native to southern California, USA. We report the first recorded instance of apparent leucism (regional pigmentation loss), in a California horn shark Heterodontus francisci (Girard 1855) and tope shark Galeorhinus galeus (Linnaeus 1758). We also report the apparent second documented occurrence of albinism in the swell shark Cephaloscyllium ventriosum (Garman 1880) from a newly hatched captive individual with parents of normal pigmentation. Lastly, we redescribe a rare secondary color morph in the leopard shark Triakis semifasciata Girard 1855 using previous literature and new sightings/images from sharks in the wild. Color aberrations may lead to different advantages (e.g., certain color morphs may offer additional camouflage) or disadvantages (e.g., reduced pigmentation may limit camouflage and protection from ultraviolet light). Documenting these rare color aberrations augments our understanding of how color patterns can vary between individuals and taxa, and ultimately how these conditions potentially impact shark biology.