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Last Chance To See

Traveling in China, I began to find that it was the sounds I was hearing that confused and disoriented me most.

It occurred to me, as we tried to find a table in one of the more muffled corners of the bar, that the dolphins we had come to look for must be suffering from the same kind of problem. Their sense must be completely overwhelmed and confused.

To being with, the baiji dolphin is half-blind.

The reason for this is that there is nothing to see in the Yangtze. The water is so muddy now that visibility is not much more than a few centimeters, and as a result the baiji's eyes have atrophied through disuse.

Curiously enough, it is often possible to tell something about the changes that have occurred during an animal's evolution from the way in which its fetus develops. It's a sort of action replay. The baiji's eyes, as feeble as they are, are placed quite high up on his head to make the most of the only light that ever reaches them, i.e., from directly above. Most other dolphins have their eyes much lower down the sides of their heads, from where they can see all around them, and below; and this is exactly where you will find the eyes on a young baiji fetus.

As the fetus grows, however, its eyes gradually migrate up the sides of its head, and the muscles that would normally pull the eyeball downward don't even bother to develop. You can't see anything downward.

It may be, therefore, that the entire history of soil erosion into the Yangtze can be charted in the movement of a single fetus's eyes. (It may also be that the baiji arrived into an already turbid Yangtze from somewhere else and just adapted to its new environmental we don't know. Either way, the Yangtze has become much muddier during the history of the baiji species, mostly because of human activity.)

As a consequence, the baiji had to use a different sense to find its way around. It relies on sound. It has incredibly acute hearing, and "sees" by echolocation, emitting sequences of tiny clicks and listening for the echoes. It also communicates with other baijis by making whistling noises.

Since man invented the engine, the baiji's river world must have become a complete nightmare.

China has a pretty poor road system. It has railways, but they don't go everywhere, so the Yangtze (which in China is called the Chang Jiang, or "Long River") is the country's main highway. It's crammed with boats all the time, and always has been - but they used to be sailing boats. Now the river is constantly churned up by the engines of rusty old tramp streamers, container ships, giant ferries, passenger lines, and barges.

I said to Mark, "It must be continuous bedlam under the water."

"What?"

"I said it's hard enough for us to talk in here with this band going on, but it must be continuous bedlam under the water."

"Is that what you've been sitting here thinking all this time?"

"Yes."

"I thought you'd been quiet/"

"I was trying to imagine what it would be like to be a blind man trying to live in a discotheque. Or several competing discotheques."

"Well, it's worse than that, isn't it?" Mark said. "Dolphins rely on sound to see with."

"All right, so it would be like a deaf man living in a discotheque."

"Why?"

"All the stroboscopic lights and flares and mirrors and lasers and things. Constantly confusing information. After a day or two you'd become completely bewildered and disoriented and start to fall over the furniture."

"Well, that's exactly what's happening, in fact. The dolphins are continually being hit by boats or mangled in their propeller or tangles in fishermen's nets. A dolphin's echolocation is usually good enough for it to find a small ring on the sea bed, so things must be pretty serious if it cant tell that it's about to be brained by a boat.

"The, of course, there's all the sewage, the chemical and industrial waste and artificial fertilizer that's being washed into the Yangtze, poisoning the water and poisoning the fish."

"So," I said, "what do you do if you're either half-blind, or half-deaf, living in a discotheque with a stroboscopic light show, where the sewers are overflowing, the ceiling and the fans keep crashing on your head, and the food is bad?"

"I think I'd complain to the management."

"They can't."

"No. They have to wait for the management to notice."

If two people in Metafilter hadn't mentioned Last Chance To See I might have missed the chance to read one of the best books ever. Combining Douglas Adams's sense of humor with a story on endangered species is a win-win situation if you ask me.