Wild Ocean Blue

If you’re a tweeter and you’ve been following my tweets lately, you might have noticed a fair few stories from the cetacean world showing up. Reason being, there have been lots of whale and dolphin studies out in the last few weeks.

And here is a selection of the recent stories I think are most interesting, important, or both.

Photo by kaladrakas

For starters there was news that dolphins are picky eaters.

Previously, scientists thought that common dolphins (Delphinus delphis) pretty much eat whatever they find. But now it turns out they prefer eating certain fish with a high fat content, presumably because with their active lifestyle they need all the energy they can get.

To find out what they have been eating, Jerome Spitz from the University of La Rochelle rummaged around inside the stomachs of dolphins caught by tuna drift nets in the Bay of Biscay.

Common dolphin. Photo by Chris Gray

He discovered that dolphins ignore common fish with a low energy content, and make a b-line for less abundant lanternfish.

So it turns out for common dolphins only the best will do.

Leviathan lives – or at least it did 12 million years ago

New fossils have been found in Peru of a very scary sea monster that patrolled the seas until it went extinct several million years ago.

It looked rather like a sperm whale, only it was much more dangerous. Sperm whales don’t have upper-teeth, so they have to suck up their food. These ancient whales came fully equipped with two bristling rows of enormous fangs, the size of a machete (up to 36 cm or around 10 inches) – all the better for gobbling down large prey, probably other whales.

It roamed the oceans at the same time as Carcharocles megalodon, the 15m / 50foot and now extinct version of a great white shark – together they would have been a pair of serious ocean troublemakers.

The folks who discovered this new oceanic beast – which probably had the biggest, scariest mouth of any 4-legged creature we know of – have rather sweetly named it Leviathan melvillei, after their literary inspiration.

We also heard that sperm whales are carbon neutral

Talking of sperm whales… iron in modern sperm whale poo fertilizes the oceans, triggering a bloom of carbon-sucking phytoplankton, some of which end up as whale food. A neat cycle indeed.

Sperm whale tail. Photo by Adrian Midgley

The iron boost from each whale stimulates enough plantlife to counteract their own exhalations of carbon dioxide. The key is that the whales eat squid down in the dark depths and defecate nearer the sunny surface, bringing lots of iron with them. In the Southern Ocean alone, sperm whales bring up 50 tonnes of iron a year.

Sadly, whale hunting may have already reduced the ability of the oceans to lock away carbon dioxide from the atmosphere.

Bad news for finless porpoises

And finally, there was bad news for the finless porpoise (Neophocaena phocaenoides) – an odd looking fellow (unlike most other dolphins and porpoises, it doesn’t have a fin on its back).

The problem is, what we thought was one species could well be at least two. The small population of less than a thousand porpoises living in China’s Yangtze River could be headed the way of the Baiji river dolphin which three years ago was pronounced extinct in the wild.

Finless porpoise. Photo by ori2uru

Finless porpoises live across the Indo-Pacific, but it turns out the Yangtze porpoises have very different genetics to all the others, suggesting they are somewhat isolated and should be protected as a separate population. The Yellow Sea and South China Sea populations also appear to be distinct from each other.

The jury is still out over whether they are different enough to count as a separate species.

Sorry to end on a gloomy note, but it looks like – if we’re not careful – the Yangtze River could be the site of the next cetacean extinction that happens during on our watch.