Survivors: The Animals and Plants that Time Has Left Behind

Richard Fortey's new book, a delight like all its predecessors, considers what are commonly termed "living fossils", in other words, plants and animals that have shown very little change, often for hundreds of millions of years. That said, Fortey doesn't actually like the term "living fossils", for nothing is ever fixed and even the most ancient organisms change through time, however slowly and however slightly. Fortey is a palaeontologist, so the search for living organisms is something of a departure for him. But he has criss-crossed the world in search of them, and he describes the various animal and plant survivors and their environments in eloquent detail, along with often humorous anecdotes about his journeys.

So, what are these survivors? First we have the American horseshoe crab, Limulus, whose ancestors can be traced back to the Ordovician. Their nocturnal breeding journeys to the Delaware coast are described superbly: the clattering percussion as they move on to land, and the flocks of cawing, swarming birds that feed on the eggs. Fortey conjures up the scene so exquisitely that the reader feels that he is there. Likewise the search, in various parts of the southern hemisphere, for the terrestrial "velvet worm", Peripatus, is beautifully described. These had many close relatives in Cambrian seas; their terrestrial descendants survived, while the marine versions died out.

Then we have a fine chapter on living prokaryotes, ancient slimy filaments and spheres lacking a nucleus in the cell, which in some instances form columnar stromatolites, as they have done for 3.5 trillion years or so. Living forms are still present in Shark Bay, Western Australia, finely recorded here.

But what about extremophiles? These are archaea (distinct from bacteria), some of which can live in water of 131C, surely retaining this capacity from the ferociously harsh environments of the early Earth. Fortey's descriptions of the multicoloured bands of different extremophiles bordering hot lakes in Yellowstone National Park are magical. We are taken, too, to mudflats off Hong Kong to study the living brachiopod Lingula, truly a survivor from the Cambrian, and we learn about many other kinds of invertebrate living fossils. There is the clam Solemya, which is virtually gutless but cultivates sulphur bacteria on its gills upon which it lives, and seems to have done so since the Ordovician. There is the living Nautilus; there is the bivalve Neotrigonia, with Jurassic equivalents; there are sponges, jellyfish and so much else; and each case is treated with enthusiasm and perception.

What, then, about plants? First we have Huperzia, so similar to the earliest clubmosses whose descendants dominated the Carboniferous coal forests. The story of Ginkgo is treated admirably, and Araucaria, as is the latest discovery, the fair-sized Wollemia, known just since 1994, found only in a deep valley in New South Wales, which must be reached by abseiling from above. As its pollen shows, it has a 90-million-year pedigree.

Finally we have the vertebrates. Here, Fortey offers fascinating tales of lampreys, modern descendants of jawless fishes; the primitive Australian mammals platypus and echidna; the tuatara; island mammals and Ice Age survivors; and the tragic story of the near extermination of the American bison - and plenty more besides.

But a serious question remains: why should there be survivors at all, and particularly these ones? There have been environmental catastrophes aplenty, including the mass extinctions at the end of the Ordovician, late Devonian, end Permian, end Triassic and final Cretaceous. Yet even so, some particular habitats endured, and with them, their organisms. Consider Lingula and Solemya, sometimes found together in the intertidal mudflats that have always been available whatever the global perturbations may have been. Stick-in-the-muds last longest, it is true, but Fortey coins for us a beautifully concise concept - he calls such refugia "time havens". This focuses attention ideally, especially for the terrestrial time havens that are most easily identified.

So are there any biological qualities that facilitate survivorship? Longevity certainly helps. So does having few large eggs or babies, giving the young a better start in life. Ultimately, however, it is a matter of being in the right place at the right time. Even so, all living organisms will become extinct, ourselves included. But before you do, take time to read this fascinating and superbly illustrated book.