07.05.2022 – Dark yet colourful

There’s so much beauty in variety and dolphin pods are brimming with it. One of the most abundant species during the winter months is the Short-beaked common dolphin (Delphinus delphis), a gorgeous dolphin that is easily recognisable through their hourglass-like, yellow flank pattern. This beautiful characteristic that, along with their curious nature, made them a favourite amongst ancient Roman, Greek and Minoan artists, who immortalised the animals in art pieces. Their interactive nature also makes them wonderfully easy to admire and we had the pleasure of observing several of these beauties bow-riding our traditional vessels waves today.

What few people notice is that this hourglass pattern and the characteristic colouring varies amongst individuals of the species. An illustration by Lucas Frédérique clearly depicts the heterogeneity of coloration patterns amongst individuals, ranging from intensely coloured Hyper-pigmented individuals, to the pale hypo-pigmented types up to a series of oddities and unique patterns. Melanism, an overproduction of the dark pigment melanin due to a mutation, is an increasingly common form of hyper-pigmentation that leads to individuals completely losing their hourglass coloration. We had two such individuals within todays pod of dolphins, perfectly integrated amongst their conspecifics and ironically adding a little more colour to the enormous pod.

While records of melanistic individuals continue to be extensively documented, some would argue that colour variations may also be a result of hybridization. Hybrids are the offspring of two different parent species and, while hybrids are possible and have been recorded even for common dolphins, hybridisations are rarely successful even under controlled conditions in captivity and usually result in infertile offspring. Melanism, on the other hand, seems to be a mutation that is easily passed from parent to offspring. We’ve had countless sightings of melanistic calves and their mothers which proved that the mutation may provide the individuals with some sort of benefits. The anomaly, however, remains to be better understood.

Whatever the colour or colour variation, the features intensify as the animals age. This was perfectly visible on a tiny little calf accompanying the group. Its faded hourglass pattern as well as the accompanying birthmarks, deep stripes along its flank, indicated that the animal was born very recently. What joy and variety these gorgeous dolphins bring, let’s enjoy them as much as possible before they leave for colder waters in the north.

By Paula Thake

Sightings of the day

Ribeira Brava

14:30 Short-beaked common dolphins