Feeding Strategies and Tactics

Abstract

Marine mammals are found in a wide range of habitats including the open ocean, coastal waters, rivers, lakes, and even on ice floes and land. They feed on a variety of prey species from aquatic plants to microscopic zooplankton to the largest marine mammals, and a diverse array of strategies and tactics is used to locate and capture these prey. Some marine mammals consume huge numbers of prey items at a time (batch feeding) while others attack and consume prey items singly (raptorial feeding). Marine mammals have many ways to detect their prey including vision, various types of mechanoreception, echolocation, and hearing. Most marine mammals appear to rely on vision to at least some extent. The large, forward pointing eyes of pinnipeds suggest that vision is an important method for detecting prey. Even species that dive to extreme depths, like the elephant seal, are capable of using vision to find prey in dark waters at their foraging depth. Vision may be less important in other taxa. River dolphins (Platanista gangetica) of the Indian subcontinent have eyes that are greatly reduced and may be mostly blind. Sea otters can use their forepaws to find food and discriminate prey items without the aid of vision, and many pinnipeds are found in turbid waters, making vision a poor method of prey detection.