South Yarmouth, Massachusetts. It is jellyfish season, and for Nantucket Sound this means the arrival of the giant leatherback sea turtle – Dermochelys coriacea. Each July, as coastal waters warm up, various species of jellies show en masse to feed on the rich soup of planktonic life that thrives offshore of New England. And once these jellies arrive to feed, the leatherback sea turtle is sure to follow, in turn feeding on them.
The leatherback is the largest of the world’s sea turtle species, averaging 1.83–2.2 metres (6.0–7.2 ft) in total length. It is also the most ancient, having swam our planet’s ocean for some 110 million years, since the Cretaceous Period. This massive, ancient reptile is unfortunately extremely endangered. Suffering not so much from direct hunting by humans, it has declined worldwide from an unpleasant cocktail of indiscriminate catch on our fishing nets and lines, loss of highly selective nesting sites via beachside development, and by choking on our plastic trash, which it confuses for its primary food source – the jellies.
My work has led me to Nantucket Sound this summer to act as an observer for endangered species off a research vessel that is mapping seafloor. My arrival to the Cape Cod area has coincided with that of this mighty turtle, and I’ve had the good fortune of crossing paths more than once now. In fact, the unmistakable profile and polka-dotted body art of the leatherback has surfaced alongside my work vessel a handful of times already. I noticed its food source – in abundance – long before I saw the turtles themselves. Nettles, moon jellies and ctenophores are everywhere in these waters right now. Yet, the first time I witnessed the emergence of an animal the size of a Volkswagen Bug, my brain had trouble believing what my eyes were telling me. These animals are both massive and graceful, and make themselves known to people out on the water when they surface briefly for air.
Header photo (top of post): A leatherback sea turtle (Dermochelys coriacea) off the coast of Brazil. Photo: Projeto Tamar Brazil