Wednesday, 27 December 2006

Sea's greetings

I'm back from my few days of indolence. Not much to report, obviously, because indolence doesn't lend itself to exciting anecdotes. Come to think of it, it doesn't even lend itself to boring ones.

So what's been happening elsewhere?

Yesterday, an unlucky New Zealander had an unexpectedly close encounter with a bottle-nosed dolphin. She was sitting in the bow of a small boat when the dolphin leapt out of the water. Unfortunately, it mistimed the jump and crashed into her, causing severe internal injuries.

Whereas most newspapers reported the incident as a freak accident, Glasgow's Daily Record wasn't having any truck with logic and reason.

Crazed dolphin leaves woman seriously hurt after boat attack

(Seems that the subeditor used up all imagination on that headline. This one wasn't half as inventive: FLATULENT TURTLE SETS OFF ALARMS.)

Fish have been doing interesting things as well.

Scientists working in the Red Sea have turned up evidence of co-operative hunting between groupers (Plectropomus pessuliferus) and moray eels (Gymnothorax javanicus). The groupers hunt prey around coral reefs; the eels pick food out of the crevices and crannies within the reef. Prey fleeing from one type of predator swim into the maw of the other. Between them, the two species of fish have the area sewn up.

From the authors' synopsis:
The article offers a description and accompanying videos, such as the one showing a grouper and eel swimming side by side as if they are good friends on a stroll. It also offers quantification, which is truly hard to achieve in the field, of the tendencies involved in this mutually beneficial arrangement. The investigators were able to demonstrate that the two predators seek each other’s company, spending more time together than expected by chance. They also found that groupers actively recruit moray eels through a curious head shake made close to the moray eel’s head to which the eel responds by leaving its crevice and joining the grouper. Groupers showed such recruitment more often when hungry.

But that's not the only recent surprise in the world of marine ichthyology. Sedate and slow-moving batfish have been hiding their lights under large, leaf-shaped bushels. They may be the saviours of the reef.

Increased nutrients and over-fishing of marine herbivores have led to an increase in weed growth on coral reefs. Weed smothers the coral. The coral declines and the weed takes over completely. This shift in dominance is not easy to remedy.

However, marine biologists from James Cook University were surprised to find that it could happen naturally when batfish (Platax pinnatus) moved in. Why were they surprised? Batfish weren't known to be herbivores. Until this study, they were thought to feed only on invertebrates. But not only were they algal grazers, they were voracious enough to tip the balance back in favour of the coral.

But the biggest (ahem) marine biology story of December has to be that of the giant squid caught off Japan. This individual isn't a whopper as far as giant squid go but it's large enough for "calamari rings the size of truck tyres". (Line stolen from cephalopod expert Mark Norman.)

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