摘要:

AbstractKiller Whales are well‐known as predators of other marine mammals, including the large Sperm and baleen whales. Members of all marine mammal families, except the river dolphins and manatees, have been recorded as prey of Killer Whales; attacks have been observed on 20 species of cetaceans, 14 species of pinnipeds, the Sea Otter, and the Dugong. Ecological interactions have not been systematically studied and further work may indicate that the Killer Whale is a more important predator for some populations than previously believed. Not all behavioural interactions between Killer Whales and other marine mammal species result in predation, however. Some involve ‘harassment’ by the Killer Whales, feeding by both species in the same area, porpoises playing around Killer Whales, both species apparently ‘ignoring’ each other, and even apparently unprovoked attacks on Killer Whales by sea lions. These non‐predatory interactions are relatively common. We conclude that interactions between Killer Whales and marine mammals are complex, involving many different factors that we are just beginning to

ISSN:0305-1838    

DOI:10.1111/j.1365-2907.1991.tb00291.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractResearch into dolphin swimming has historically been guided by false assumptions of ‘effortless’, ‘high‐speed’ swimming. These assumptions have instigated the development of drag‐reduction hypotheses but tests of these hypotheses have generally had little success. The autecological approach has dominated recent efforts and has been more successful. In this review we summarize results of decades of research efforts to study these creatures. (1) Drag is minimized primarily by the streamlined shape of the body and appendages, with no known contributions from compliant dampening, dermal ridges, secretions, boundary layer heating, or skin folds. All indications are that the boundary layer is turbulent. (2) Muscles for the upstroke and downstroke of swimming dolphins provide approximately equal power. (3) Output force is enhanced by insertions occurring on the long processes of the vertebrae and on the subdermal connective tissue sheath. (4) Measured swimming speeds are lower than previously believed, with maximum reported routine speeds being approximately 3 m/s. (5) Porpoising behaviour appears to be the most energetically conservative manner in which to breathe when swimming at high speed. (6) Riding surf and wind waves involves the balance between the wave slope and the weight of the animal whereas riding the bow wave involves the interaction of the pressure wave in front of a ship and the drag of

ISSN:0305-1838    

DOI:10.1111/j.1365-2907.1991.tb00292.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

ISSN:0305-1838    

DOI:10.1111/j.1365-2907.1991.tb00293.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY