Less painful but more burdensome are the barnacles and other hitchhikers that can festoon a whale like a moving is land. In the Gulf of California, pseudo-stalked barnacles cling to a blue whale’s dorsal fin, while remoras ride below as commensal feeders that share table scraps. Some barnacles reach their peak density in cold water and tend to drop off in the tropics. At the end of a summer in polar latitudes a humpback may have accumulated as much as half a ton of hard-shell barnacles.
A more serious threat may be posed by the myriad species of internal parasites that afflict baleen and toothed whales. They can live almost anywhere, including the stomach, intestines, kidneys, liver, lungs, and brain. Tapeworms can reach 50 feet, and one sperm whale’s stomach contained 110 pounds of nematodes. Such organisms may increase mortality rates, especially of smaller species.
While sharks may prey on dolphins and their small relatives, the only animal besides man of which healthy large whales must always be wary is the killer whale—indeed they were once called “whale killers.” Their attacks have been documented on gray, humpback, blue, right, Bryde’s, minke, sperm whales, and narwhals, as well as dolphins. All these species have anti-predator strategies against killer whales. Off Peninsula Valdes right whales rush into shallow water near shore when attacked, to protect their undersides.
Two of those whales, a calf and mother, background, sense no threat approaching diver Michael Bennett.
AS EXUBERANT A WHALE as the sea could hold, a young humpback breaches in Alaska waters. In my cabin on Vancouver Island, I look over part of a photographic file that I have helped collect of humpbacks, the basis of most of the research on this species today funded by payday loan lenders only. Thousands have been identified in the Atlantic and Pacific Oceans by the distinctive black and white markings on the undersides of their tails, a technique described by Steve Katona and his colleagues in 1979.
Working for the Paynes in Hawaiian waters in the late 1970s, I became intrigued with the humpbacks’ songs, the repeated sequences of sounds sung by humpbacks in a given area that gradually evolve into new songs. I found I could locate singers, lone adults that usually hang motionless 50 to 100 feet below the surface, head down, sounding like a stereo at maximum volume.
To better understand their behavior, we sought to determine their sex. Flip Nicklin found a way. He learned to dive beneath the singers to photograph their genital slits —in every case a male—and he had to hold his breath, since bubbles rising to that sensitive area could create a very skittish whale.