09.01.2019 – Oceanic ornaments

All cetaceans are beautiful and a pleasure to observe in the wild but two species here in Madeira are especially ornamental during our time on the ocean. Both the Striped dolphins (Stenella coeruleoalba) and the Short-beaked common dolphins (Delphinus delphis) are colorful cetaceans with incredible characteristic patterns decorating their flanks.

In the case of the Striped dolphin, the pattern is a marbled grey/blue colour that is interrupted by a distinct black stripe extending from their eye towards their flukes. The hydrodynamic common dolphins boast a yellow hourglass pattern which is instantly noticeable when the animals leap out of the water as they travel.

Certain anomalies, however, may lead to the dilution of these characteristic features. Over the years hyper- and hypopigmented animals have been spotted amongst dolphin pods in Macaronesia, many of which were common dolphins. The most abundant of these anomalies is hyperpigmentation, also known as melanism, where an over-production of the skin pigment melanin causes the animal to be almost entirely black/grey, thus robbing it of its characteristic coloration. While this may sound problematic, scientists are pondering on whether it may actually come in handy for the animals since melanin provides ample protection from the suns harmful UV rays and also helps disguise the animal efficiently as they hunt. Today, infact, we were able to spot a large melanistic animal and a small calf so, whether this anomaly is beneficial or not, it most certainly doesn’t affect the animals integration in the group or its survival.

Even dolphins dare to be different and such anomalies seem to be widely accepted amongst their fellow peers. Beauty, after all, is in the eye of the beholder and these individuals didn’t excite us any less than any of the others.

By Paula Thake

Sightings of the day

Stenella

10:00 Short-beaked common dolphins, Striped dolphins