In times of extreme stress, the whole concept of fitness, at least in a Darwinian sense, loses its meaning: how could a creature be adapted, either well or ill, for conditions it has never before encountered in its entire evolutionary history? At such moments, what Paul Taylor, a paleontologist at London’s Natural History Museum, calls “the rules of the survival game” abruptly change. Traits that for many millions of years were advantageous all of a sudden become lethal (though it may be difficult, millions of years after the fact, to identify just what those traits were).

Installed in tanks in a basement laboratory, the animals Buia and Hall-Spencer gathered from around Castello Aragonese at first appear inert— to my untrained eye, possibly even dead. There is a six-inch-long sea cucumber, which bears an unfortunate resemblance to a blood sausage or, worse yet, a turd.

Among the fish that I think I may have spotted were: tiger sharks, lemon sharks, gray reef sharks, blue-spine unicorn fish, yellow boxfish, spotted boxfish, conspicuous angelfish, Barrier Reef anemonefish, Barrier Reef chromis, minifin parrotfish, Pacific longnose parrotfish, somber sweetlips, fourspot herring, yellowfin tuna, common dolphinfish, deceiver fangblenny, yellow spotted sawtail, barred rabbitfish, blunt-headed wrasse, and striped cleaner wrasse.

But it was the limits of dispersal that made things interesting. These accounted for life’s richness and, at the same time, for the patterns that could be discerned amid the variety. The barriers imposed by the oceans, for instance, explained why vast tracts of South America, Africa, and Australia, though in Darwin’s words “entirely similar” in climate and topography, were populated by entirely dissimilar flora and fauna. The creatures on each continent had evolved separately, and in this way, physical isolation had been transmuted into biological disparity.

From the standpoint of the world’s biota, global travel represents a radically new phenomenon and, at the same time, a replay of the very old. The drifting apart of the continents that Wegener deduced from the fossil record is now being reversed— another way in which humans are running geologic history backward and at high speed. Think of it as a souped-up version of plate tectonics, minus the plates. By transporting Asian species to North America, and North American species to Australia, and Australian species to Africa, and European species to Antarctica, we are, in effect, reassembling the world into one enormous supercontinent— what biologists sometimes refer to as the New Pangaea.

Even clearer is the evidence from New Zealand. When the Maori reached New Zealand, around the time of Dante, they found nine species of moa living on the North and South Islands. By the time European settlers arrived, in the early eighteen hundreds, not a single moa was to be seen. What remained were huge middens of moa bones, as well as the ruins of large outdoor ovens— leftovers of great, big bird barbecues. A recent study concluded that the moas were probably eliminated in a matter of decades. A phrase survives in Maori referring, obliquely, to the slaughter: Kua ngaro i te ngaro o te moa. Or “lost as the moa is lost.”

Before humans emerged on the scene, being large and slow to reproduce was a highly successful strategy, and outsized creatures dominated the planet. Then, in what amounts to a geologic instant, this strategy became a loser’s game. And so it remains today, which is why elephants and bears and big cats are in so much trouble and why Suci is one of the world’s last remaining Sumatran rhinos.