Fish 475: Marine Mammalogy 20 May 2009 Trophic biology II Anthony J. Orr SAFS/UW & NMFS/NOAA Course website: http://faculty.washington.edu/glennvb/fish475
1 Trophic biology of pinnipeds Otariids: Shallow divers 1) Specialists on organisms of the vertically-migrating deep scattering layer (DSL), particularly small fish and, cephalopods, or: 2) Coastal forage fish specialists
Trophic biology of pinnipeds 2 Otariids as central place foragers during breeding season NOAA
Trophic biology of pinnipeds 3 Otariids in the nonbreeding season: In some species (e.g., northern fur seals), ties to land are abandoned. In others (e.g., Steller sea lions), ties to haulouts and coastal habitats are maintained yearround. NOAA
Trophic biology of pinnipeds 4 Phocids: Variable in feeding anatomy and diving behavior - Most do not forage at all during lactation; - May or may not be central place foragers.
Trophic biology of pinnipeds 5 Phocid case studies: 1) Crabeater seal: Feed primarily on krill; Post-canine teeth modified as filters,
Trophic biology of pinnipeds 6 Phocid case studies: 2) Leopard seal: Feed on penguins & small fur seals...
Trophic biology of pinnipeds 7 Phocid case studies: 2) Leopard seal:.... and they also feed on krill! (check out the postcanine teeth)
Trophic biology of pinnipeds 8 Phocid case studies: 3) Northern elephant seals: Feed on DSL and abyssal fish and cephalopods; Make two extended excursions to the open sea each year
Trophic biology of pinnipeds 9 Phocid case studies: 4) Hawaiian monk seals Feed on coral reef fishes and crustaceans; Limited to tropical latitudes.
Trophic biology of pinnipeds 10 Phocid case studies: 5) Harbor seals: One of few phocids that forages while nursing a pup; Widespread in North Pacific and North Atlantic; Feed on a variety of coastal fishes, including herring, hake, salmon, surf perch, and rockfish
Walruses: Benthic feeding: Trophic biology of pinnipeds 11 G. Anderson Sedimentary habitats Shallow water (<100m) Invertebrate prey, primarily clams (up to 5000 ingested per feeding session); Utilize vibrissae to locate prey; G. Anderson Utilize water jets, fanning of sediment with flippers, and shoveling with muzzle to excavate prey; Utilize suction to extract prey tissue from shells G. Ehlme G. Ehlme
Trophic biology of pinnipeds 12 Walruses: Benthic feeding: Important influence on the structure and dynamics of the benthic communities in Arctic regions: Alaska Department of Fish & Game Modification of clam density and demography; Physical effects on sediments, with biological consequences Oliver et al. 1983
Trophic biology of pinnipeds 13 Walruses: Benthic feeding: Cool underwater videos! Goran Ehlme Reference: Levermann, N., A. Galatius, G. Ehlme, S. Rysgaard, and E.W. Born. 2003. Feeding behavior of free-ranging walruses with notes on apparent dextrality of flipper use. BMC Ecology 3: 9.
Polar bear foraging 1 Primary foraging habitat: Sea ice; Primary prey: Phocid seals on the ice. Key influence on all aspects of the life histories of Arctic pinnipeds; Also prey on walrus and belugas.
2 Polar bear foraging When stranded on land as a result of poor ice conditions: Feed on whatever is available and catchable, including vegetation.
1 Sirenian foraging Key general patterns: 1. All species herbivorous; 2. All species with dentition resembling terrestrial mammalian herbivores and designed for grinding vegetation; 3. All species with continuously deciduous teeth, erupting in the posterior jaw, moving forward, and shedding from the anterior jaw; 4. All species with primary cellulose digestion in the colon (similar to elephants and hyraxes); 5. All species with relatively low metabolic rates and, with some exceptions, minimal cold tolerance.
2 Sirenian foraging Key general patterns: 1. All species herbivorous
3 Sirenian foraging Manatee Key general patterns: 2. All species with dentition resembling terrestrial mammalian herbivores and designed for grinding vegetation Manatee Reindeer
4 Sirenian foraging West Indian manatee Key general patterns: 3. All species with continuously deciduous teeth, erupting in the posterior jaw, moving forward, and shedding from the anterior jaw Shedding of oldest teeth New eruptions
Sirenian foraging 5 Key general patterns: 4. All species with primary cellulose digestion in the colon (similar to elephants and hyraxes)
6 Sirenian foraging Key general patterns: 5. All species with relatively low metabolic rates and, with some exceptions, minimal cold tolerance.
7 Sirenian foraging Patterns by families: Dugongs (dugongidae): Obligate bottom feeders; Forage primarily on sea grasses; May cause ecologically significant disturbance to sedimentary ecosystems.
Sirenian foraging 8 Patterns by families: Sea cows (hydrodamalidae or dugongidae): Obligate surface feeders; Forage primarily on kelps; Probably able to forage in the rocky intertidal zone during winter despite great size and limited mobility.
Sirenian foraging 9 Patterns by families: Manatees (trichechidae): Generalized feeders; Consume a wide variety of plant types at surface, midwater, and on the bottom; Amazonian manatee may be able to tolerate obligatory seasonal fasts imposed by seasonal changes in river water levels.