How unique is a slim elephant with huge feet?

There is one 13-foot hairless animal with a long flexible snout that stands out even among its own thundering herd.

It is a Namibian (South-West African) elephant with exceptionally large feet.

The animal's big feet help it walk across sand. They are tough enough for steep climbs over jagged rock, which the elephant accomplishes with great agility.

And for an elephant, it looks positively slim. Indeed, it looks as if it could use an extra helping of tree branches.

Not much chance of that though. This elephant lives in the desert -- the feature that makes it unique among elephants in the world, according to those who have studied it.

This desert elephant roams the northwest region of Namibia (South-West Africa) -- the territory administered by South Africa that is the subject of international negotiations for independence.

But just as the political future of Namibia is in doubt, so are the prospects of survival for this huge gray mammal. Extended drought, poaching, and lack of any organized protection effort have contributed to a steady dwindling of the elephants.

Wildlife conservationist Clive Walker has studied these elephants since 1977. He figures their numbers have declined from at least 600 in the early part of this century to some 84 today.

In the early 1970s the South African government asked zoologist Fritz Eloff of the University of Pretoria to draw up a conservation plan for Kaokoland, a black tribal ''state'' in Namibia where the animals roam.

On sighting the elephants, Professor Eloff says he was struck by their ''unique'' features.

''I knew they were something extraordinary,'' he says. ''We found elephant tracks in sheer desert country where there was no vegetation at all,'' he recalls.

But a conservation plan was never implemented. However, Eloff and Walker are working together with two South Africa preservation organizations to save the elephants from extinction.

They want to set up a mobile antipoaching unit in the region to protect the elephants from illegal ivory hunters. Damaraland, a black ''state'' south of Kaokoland, has agreed to help.

Mr. Walker says one of the reasons the elephant has not been protected is that Namibia has not recognized it as a biologically or genetically unique group. The feeling among some officials is that the desert elephants interbreed with those in the nearby Etosha game reserve, where there are plenty of elephants.

However, Walker says research over the past 18 months has convinced him there is no mixing and that the desert elephants are a distinct ''subpopulation.''

Whether these elephants prove in the end genetically distinct may be beside the point from a conservation point of view. Professor Eloff says their adaptations to their desert environment make them special, regardless.

The territory these desert elephants inhabit is huge - some 19,000 square miles. It ranges from the flat, dry coast of northwest Namibia to the sparsely vegetated 6,000-foot mountains in the interior. Walker says the elephants make use of it all.

Their water retention is exceptional, he says, and they travel up to 55 miles at night in search of scarce water. But northwest Namibia is suffering from a drought that has gone on for five seasons.

Mr. Walker believes the elephants will survive the drought. And some January precipitation raises his hopes of a normal season of summer rain.

But the drought has apparently contributed to poaching - perhaps by farmers desperate for income. Harsh conditions and vast territory concerned make it difficult to stop the poachers.

There has also been concern that South African military men in Namibia might be shooting the elephants for sport. There was a reported incident in the mid- 1970s of an elephant shot from a military helicopter. And last December a South African Defense Force man was charged with shooting an elephant for sport. Walker says the defense force has assured him it is doing all it can to enforce the law against hunting elephants.

Shooting an elephant can carry $6,000 fine. But illegal financial rewards appear attractive nonetheless. Ivory can fetch $60 to $70 per kilogram, and a good pair of tusks can bring someone several thousand dollars.