Wildlife

Millions of dead jellyfish are washing up around the world

The by-the-wind sailor jellyfish (Velella velella) spends its days drifting aimlessly through the open sea, gorging itself on an endless buffet of complementary morsels.

Every year, on beaches around the world, colonies of sailor jellies become stranded by the thousands. There, they dry up and die, becoming a “crunchy carpet” of dehydrated corpses covering the sand. Sailor jelly strandings are common when seasonal winds change course, but some — like a 2006 event on the west coast of New Zealand — are on another level entirely, with the jellyfish corpses numbering not in the thousands, but in the millions. During spring months from 2015 to 2019, dead jellyfish littered more than 620 miles (1,000 kilometers) of continuous coastline

These exceptional jellyfish die-offs coincided with a massive marine heat wave known as “the blob.” Beginning in 2013, surface waters off the Pacific coast began heating up to levels never recorded before. The intense warming continued through 2016, tampering with every level of the marine food chain and resulting in mass die-offs of seabirds, baleen whales, sea lions and other creatures. According to a new study, it’s likely that the blob drove the mass die-offs of by-the-wind sailor jellyfish reported during those years.

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