- Stung! On Jellyfish Blooms and the Future of the Ocean by Lisa-Ann Gershwin
Chicago, 424 pp, £19.50, May 2013, ISBN 978 0 226 02010 5
Near the end of H.G. Wells’s The Time Machine, the Time Traveller finds himself on a desolate beach in the distant future. Under a lurid red sky, by a slack, oily sea, he is set upon by giant crabs, last survivors in a dying world – ‘foul, slow-stirring monsters’, with ‘vast, ungainly claws smeared with an algal slime’. If Wells were writing that scene today, the jellyfish would be a much better candidate than the crab for the part of the doomsday creature on the terminal beach. According to Lisa-Ann Gershwin’s disturbing book, the jellyfish is an ‘angel of death’, a harbinger of ‘planetary doom’ likely to be the ‘last man standing’ in what she describes as our ‘gelatinous future’.
Jellyfish are immensely old. From the fossil evidence, we know that they dominated the oceans for millions of years before predators with bones or shells or teeth evolved. ‘Through the eons,’ Gerswhin writes, ‘while trilobites and dinosaurs came and went and plants and animals moved onto land and evolved respiratory machinery and mammals evolved bigger and better brains, jellyfish stayed the same.’ With no brain, no heart, no lungs and no gills, they are ‘simple but effective’ – ‘essentially a gelatinous body with one or more mouths for ingesting food, one or more stomachs for digesting food, and usually four or eight gonads for making more jellyfish’. Species of the phylum Cnidaria – the classic jelly – have existed in something close to their current form for at least 565 million years; Ctenophora, the comb jellies, are not much younger. They survived the ‘big five’ mass extinctions. And now, it seems, they are experiencing a renaissance.
Stung! is a serious monograph, a guide to jellyfish biology and to the recent explosion in jellyfish blooms by an expert in the field. (Gershwin has devoted her working life to marine invertebrates and has discovered more than 150 new species; an American, she is now the director of the Australian Marine Stinger Advisory – ‘Consulting on all aspects of marine stinger management’.) But it’s a serious monograph disguised, quite convincingly, as a monster movie. It begins with a series of horrifying vignettes of jellyfish on the rampage, such as the ‘mass fish-kill’ events suffered by salmon farms. In 1998, a swarm of large Aurelia (the standard moon jelly) moved into Big Glory Bay off New Zealand’s South Island, and killed 56,000 three-kilo salmon in their pens within half an hour. Gershwin describes the incident in terrible detail:
The salmon all swim in one direction inside the circular pens, creating a fairly strong vortex that sucks water from the surrounding area. The Aurelia, being passive drifters, became entrained in the vortex. Too large to pass through the mesh, the jellyfish were pinned against the netting. As the jellyfish struggled against the current and the netting, their mucus, which is profuse and packed with stinging cells, was sucked into the cages. It appears that as the salmon inhaled the mucus, it blocked the oxygen-exchange surfaces of their gills, causing them to suffocate. The stinging cells exacerbated the problem by alarming the salmon, causing them to breathe faster, thereby serving to suffocate them faster.
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