Last Night's Television: Nature's Great Events, BBC1<br />Building The Olympic Dream, BBC2

I'm indebted to Monty Halls for the mysteriously gratifying discovery that plankton is part of a binary concept. Plankton, as he explained the other night in Monty Halls' Great Escape, is all the stuff that just swashes around going where the tide takes it. Nekton, by contrast, is all the stuff that's capable of going in the opposite direction, should it actually want to. So, drifters and swimmers, essentially, an opposition that I can't help feeling could be usefully applied to many land-based life forms as well. Anyway, having just found this out on Sunday night, I was able to show off to the children while watching Nature's Great Events, which was about the spectacular meeting between plankton and nekton that takes place every year in the seas off Alaska. The plankton, as you might have guessed, tends to come off worst in these encounters, but the most startling sequences revealed that not all members of the nekton have an easy time of it either.

The plankton blooms that form as the sea warms up are immense, apparently responsible for providing the Earth with half of its oxygen, but also creating an all-you-can-eat buffet for a huge number of marine creatures. And some of the appetites that take advantage of this bounty are vast as well. Humpback whales, which spend the summer off Hawaii, may not have eaten for six months by the time they make the long journey back to their summer feeding grounds. So, understandably, they aren't picky eaters by the time they get back, corralling huge shoals of herring with "nets" of bubbles and then launching themselves upwards from underneath, their rubber-matting jowls gaping wide. They're partial to bait balls, too, which form when the herring (pretty much all-round fall guys in this narrative) find themselves harried from underneath by murres and from above by gulls, which can only reach down a few feet.

A lovely shot showed you this swirling blob of mercury just beneath the surface, death coming piecemeal until a humpback suddenly punched through the mêlée like a bus. "I have seen humpbacks spit out big fish and sea birds," said one of the underwater photographers uncertainly, understandably a little nervous about the prospect of getting too close to a myopic whale. I was curious, too, to know how they'd got their extraordinary footage of a sea lion being battered to death by a pod of killer whales, not a situation in which you'd want the killer whale to get confused.

Building the Olympic Dream, the last of three documentaries about a four-yearly bloom of aspirational bombast, began with a wildlife sequence as well, as two fluorescent-jacketed men hunted through east London marshes for great crested newts. Because of the promise to make these Games the most ecological ever, all the newts were going to have to be provided with alternative accommodation before construction began. And it wasn't only endangered species that were getting the VIP transfer. Celia Hammond, the animal campaigner, was casing the joint for stray cats and, according to one tour guide, even solitary bees had been "translocated off the park". Quite how you persuade the bees and the cats not to come straight back, I'm not sure, but they would do well to steer clear of the site for the next few years, because, although the asbestos and the hydrocarbons have been expensively cleansed from the site, the boosterism and jargon is often asphyxiating. "What we're presenting today is a holistic, coordinated Stage D proposal," said one of the planning team, as he prepared to show off some models to the International Olympic Committee.

Everyone here counts as nekton, incidentally, swimming away gamely however adverse the tidal conditions. Lord Coe, who hasn't uttered a sentence without using the word "legacy" since London won the bid, demonstrated his ability to ignore the riptide of harsh reality in an interview given during the slowly moving riot that occurred when the Chinese handed the torch over. "Oh, I think it's going extremely well," he said. "There's a massive amount of community activity, which is always what we wanted the Games to inspire." Behind him somewhere, a community activist dashed out from the crowd with a fire extinguisher and was hurled to the ground by Chinese secret policemen.

Lord Coe probably thinks that reporters are plankton, but there was no sense of lethargic drift during press conferences, when the details of the ever-escalating costs of the Olympics created a kind of journalistic bait ball for the newsmen. Some of them came in from the top, like gulls, while others went around the underneath like murres, picking off juicy six-figure numbers at will.

Celia Hammond, meanwhile, who had been getting quite distressed about her failure to trap Black Jack, one of the last cats left on site, finally got a result. Black Jack didn't look grateful to have been rescued, engaging in a bit of open-clawed community activity with Celia's trousers.