October 30, 2015
Ghosts of the Sea
- as seen by -Ricardo Antunes
Risso’s dolphins are one of my favorite animals in the ocean.
Born with brownish grey bodies, they accumulate multiple white scars as they grow older, especially males, that become totally white. The “ghostly” shape of older individuals makes them easier to track underwater and predict where they will surface.
In the Portuguese archipelago of the Azores, these dolphins are called “moleiros,” the Portuguese word for “miller,” an allusion to the old profession where the men who worked in mills were covered in white flour dust.
We followed several dolphin nursery groups made up of mother-calf pairs. Mother dolphins emerged first with their calf shortly after. Some of them were not as white as the old males making them more difficult to track above and below the surface.
A recently born dolphin has noticeable creases. To fit in its mother’s womb, a dolphin fetus folds its body. Fetal folds can still be visible for weeks after birth (above).
In the Azores, Dr. Fleur Visser and her team have been studying Risso’s dolphin behavior for several years. I was fortunate to be part of her work following groups of these cetaceans off the south coast of Terceira Island. We still know very little about these “ghosts of the sea,” and Visser is on the forefront of the research on the species.