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9. Of Whales and Sharks and Giant Squid: Reflections on the Big, the Strange, and the Powerful
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245 The World of Whales A Matter of Size Feeding, Breeding, and Migration Diving for Food Interlude: Tales about Strange Creatures Shark! More about Big Animals in the Sea Nekton of Ancient Seas The largest animals on the planet are the great whales. The biggest among these weigh more than 20 big elephants. Modern whales arose within the last 30 million years or so, as a result of the cooling of the planet, which changed the productivity patterns of the sea in ways favorable for the development of large size. This is true both for whales that hunt (toothed whales) and for whales that filter the water containing small fish and krill and other plankton (baleen whales). Other vertebrate groups also have large animals; pinnipeds have elephant seals and walrus, sharks and their kin include whale sharks, the great white, and manta rays, and bony fishes have swordfish and sturgeon. Various unverifiable observations suggest that there are deep-sea giants yet to be discovered. Among the mollusks, the largest— the giant squid—apparently grow to well over a ton in size. Warm oceans also had large marine animals, especially among reptiles (ichthyosaurs, plesiosaurs, mosasaurs, crocodiles) and mollusks (giant ammonites). It is likely that their food requirements were met in highly productive shelf seas. THE WORLD OF WHALES “Thar she blows!” That call coming from the lookout in the masthead high above the deck of a nineteenth-century whaling vessel used to spell doom for the object of attention.1 Wholesale killing of whales continued well into the second half of the twentieth century, with large and fast metal ships armed with harpoon guns turning whale hunting into a whale removal operation, in a prime example of the “tragedy of the commons.”2 The annual catch peaked near 65,000 large whales in the years around 1960. A moratorium on whale hunting went into effect from 1985, after it was realized that continued whaling would result in the extinction of NINE Of Whales and Sharks and Giant Squid REFLECTIONS ON THE BIG, THE STRANGE, AND THE POWERFUL W.H. Berger and E.N. Shor some of the largest animals that ever lived on the planet. In our time, the call-out for whales serves to alert a throng of tourists to the presence of the animal they had come to see. Vast numbers of tourists swarm to places from which whales can be watched from land or on day trips—on the East Coast, the West Coast, among the islands of Hawaii, and off Baja California. To many people the ocean is first and foremost the habitat of whales.3 Cetaceans as a group (whales and dolphins and their kin) have the most intelligent, the most playful, the largest, and the fastest swimming animals in the sea (figs. 9.1 and 9.2). Also, they exhibit complex social behavior, as appropriate for large-brained mammals living in groups. It is now common knowledge that whales and dolphins are mammals rather than fishes, but for centuries it was thought that whales were some kind of fish.4 Cetaceans have in common a fishlike shape and a tail fluke for propulsion. Their front limbs are steering paddles ; they have lost the hind limbs of their fourfooted ancestors.5 The head is large and highly modified compared to other mammals, with elongated jaws and one or two breathing holes near the top of the skull (dolphins have one 246 O F W H A L E S A N D S H A R K S A N D G I A N T S Q U I D FIGURE 9.1. Humpback whale breaching in Hawaiian waters, as part of a social ritual. Males of this species sing. The humpback is a baleen whale. FIGURE 9.2. Highly intelligent and trainable, the small whales called dolphins entertain thousands of visitors to open-air aquariums. Here, seen on the island of Oahu, Hawaii. Dolphins are toothed whales. [54.221.26.137] Project MUSE (2024-03-29 07:29 GMT) only). There is no neck (or not much of one), the cervical vertebrae having been much shortened in the course of evolution. Hair has been lost. Insulation from cold water is by a layer of fat, and this blubber also serves to store energy in the absence of food (much like the camel’s hump). The fishlike shape is a matter of convergence—the reptilian ichthyosaurs of the Jurassic adopted the same...