The baiji’s eyes, feeble as they are, are placed quite high up on its 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 foetus.
As the foetus grows, however, its eyes gradually migrate up the sides of its head, and the muscles which would normally pull the eyeball downwards don’t even bother to develop. You can’t see anything downwards.
It may be, therefore, that the entire history of soil erosion into the Yangtze can be charted in the movement of a single baiji foetus’s eyes. (It may also be that the baiji arrived into an already turbid Yangtze from somewhere else and just adapted to its new environment; we don’t know. Either way, the Yangtze has become very much more muddy 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 the whole 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 steamers, container ships, giant ferries, passenger liners 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 propellers or tangled 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 can’t tell that it’s about to be brained by a boat.
`Then, of course, there’s all the sewage, the chemical and industrial waste and artificial fertiliser that’s being washed into the Yangtze, poisoning the water and poisoning the fish.’
`So,’ I said, ‘what do you do if you are 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.’
A little later I suggested that, as representatives of the management so to speak, perhaps we ought to try to hear what the Yangtze actually sounded like under the surface – to record it in fact. Unfortunately, since we’d only just thought of it, we didn’t have an underwater microphone with us.
‘Well, there’s one thing we can do,’ said Chris. ‘There’s a standard technique in the BBC for waterproofing a microphone in an emergency. What you do is you get the microphone and you stuff it inside a condom. Either of you got any condoms with you?’