Suffering a sea change

The oceans cover seven-tenths of our planet, and although it may not seem like it above the surface, they are very busy. Helen Scales and Christian Sardet are marine biologists: Sardet is apparently known as Uncle Plankton, and those multitudes of drifting organisms — ‘plankton’ comes from the Greek planktos, meaning to wander or drift — are his life’s work.

Scales’s focus is the shell-making creatures that are molluscs, though focus seems an inappropriate word for such a vast body of life: a 1993 survey of just one island, New Caledonia, found 2,738 distinct species, and 80 per cent of them were new to science. They are ‘some of the most abundant, cosmopolitan animals on the planet,’ Scales writes, ‘not to mention being among the toughest, smartest and strangest creatures ever to evolve’.

They include the Gumboot Chiton, the Dismal Limpet, the Gooey Duck Siphons (a Chinese delicacy) and the Cooper’s Nutmeg Snail Vampires. And the abilities and behaviours of molluscs are as bizarre as their names. Gastropods, when very young, undergo a process called torsion, which involves ‘all the major organs spinning around 180 degrees’ so that the anus shifts to a position just above the mollusc’s head. Satsuma snails amputate their single foot when chased by snakes. There is the wonder that is shell-making, whereby molluscs excrete a scaffold of protein, layer it with calcium carbonate, and make shells that are beautiful, but also wonders of geometry and engineering. That’s the science, and it is interesting, but so are other notes I took: ‘surfing sea-snails’, ‘Clusterwinks burglar alarms’, ‘sperm-shooting’ and ‘the Belligerent Rockshell’.