SIO 133 Marine Mammal Biology John Hildebrand Scripps Institution of Oceanography April 13, 2018 Biogeography, Sea Otters, Polar Bears
Marine Mammal Science Emerged as a discipline in last 20-30 years Expansion of literature 1495-1840 3 papers/year 1845-1960 28 papers/year 1961-1998 646 papers/year 1999-2004 856 papers/year Marine Mammal Science, Journal of Mammalogy, Canadian Journal of Zoology, Journal of Zoology, Fisheries Bulletin, Marine Ecology Progress Series..
Marine Mammal Science Study of Mammal Mammals Increasing technology Remote sensing acoustic, satellite time-depth recorders crittercams Molecular ecology systematics taxonomy Physiology
Cosmopolitan species Killer whales (Orcinus orca) From Hoelzel 2002
Migratory species n Prey driven: Mysticetes Block et al. 2011 n Ice driven: polar species e.g. beluga, narwhal, bowhead Month of year
Blue whale stocks From McDonald et al. 2006
Anti-tropical distribution From Hoelzel 2002
Species distribution n Pan-tropical species n E.g. Spinner dolphins (Stenella longirostris) From Hoelzel 2002
Temperature-defined distribution n Short-finned pilot whales n Long-finned pilot whales Source: Duke University, OBIS-SEAMAP
Circumpolar species Beluga whales (Delphinapterus leucas) From Hoelzel 2002
Endemic species - River dolphins From Hoelzel 2002
Porpoises Coastal species From Hoelzel 2002
Gender-variable distribution Sperm whales (Physeter macrocephalus) Source: whaletrackers.com
Marine Mammal Systematics Kingdom Animalia Phylum Chordata SubPhylum Vertebrata + backbone + dorsal hollow nerve chord + bone/cartilage internal skeleton
Class Mammalia, 4000 species Viviparous Hair Lactation via the mammary gland 4 chambered heart Diphyodont dentition- 2 sets of teeth 7 cervical vertebrae 3 inner ear ossicles Respiratory system - diaphragm Endothermy
Platypus & Echidna Marsupials Mammalian Orders Scaly Anteaters Armadillos, Sloths, Anteaters Dogs, Cats, Bears, Weasels, Pinnipeds, Otters Shrews Elephant Shrews Rabbits, Hares, Pikas Mice, Rats Gorillas, Monkeys, Baboons, Humans Tree Shrews Flying Lemurs Bats Aardvarks Even-Toed Ungulates (Deer, Cows, etc.) Whales, Dolphins, Porpoises Odd-Toed Mammals (Horses, Rhinos) Hyraxes Manatees& Dugongs Elephants
Marine Mammal Taxonomic Groupings About 126 Species across 3 Orders Order Carnivoria (38 species) Polar bears, sea otters, seals, sea lions, walruses Order Cetacea (83 species) Baleen whales, toothed whales Order Sirenia (5 species) Manatees, dugongs
Order Carnivoria Includes 5 Families of Marine Mammals Mustelidae Sea otter Ursidae Polar bear Phocidae Seals (true seal) Otariidae Sea lions (eared seals) Odobenidae - Walrus
Family Mustelidae, Subfamily Lutrinae Enhydra lutris - Sea otter - N. American - Teeth for crushing shells - Fully marine Lontra felina - Marine Otter - S. American - endangered - exclusively marine foraging
Characteristics of Otters Body mass: <5 kg in marine otter 40 kg in sea otters. Shortened limbs, Lengthened and often stout tails, Slim and elongated head, neck and body Loosely articulated axial skeleton gives serpentine appearance
Characteristics of Otters Depend on dense fur for insulation Requires constant grooming (5-10% time) Enlarged rear flippers for heat loss Dive to > 100 m Sea otter s large lung and blood volumes facilitate floatation and oxygen storage
Phylogeny of Otters Enhydra lutris Lutra (1) Old World and sea otter (2) the New World otter (3) the giant otter
Enhydra lutris Family Mustelidae
Lontra felina Family Mustelidae
Family Ursidae Ursus maritimus - Polar bear - Evolved from brown bear - Teeth more like seals/sea lions than bears - Eats arctic seals - Threatened w/ climate change due to diminished sea ice Photo by Ansgar Walk
Phylogeny of Polar Bears
Ursus maritimus - Polar bear range
Polar bear - regions Durner et al. 2009 Ecological Monographs Vol 79
Diminishing Ice Durner et al. 2009 Ecological Monographs Vol 79
Tagged Polar Bear 1985-1995 Durner et al. 2009 Ecological Monographs Vol 79
Polar Bear Resource Selection Function Durner et al. 2009 Ecological Monographs Vol 79
Polar Bear Predicted Change Optimal Habitat 2001-2010 to 2041-2050 Durner et al. 2009 Ecological Monographs Vol 79
Polar Bear body mass decreasing