Fish 475: Marine Mammalogy Taxonomy (continued) Friday, 3 April 2009 Amanda Bradford Course website: http://faculty.washington.edu/glennvb/fish475
Mysticeti: The baleen whales About 10-12 species; Formerly highly abundant in all the world s oceans and seas; Many species and populations depleted by commercial harvest Concentrated in or near regions of high productivity; Often make major migrations. Text reading reference: Section 1.2.2.1
General characteristics of the Mysticetes I: 1. Skulls Symmetrical; 2. Dorsal skull surface flat or convex; 3. Mandibles not articulated distally; 4. Teeth entire replaced by baleen in all species.
General characteristics of the Mysticetes II: 5. Great size and mass; 6. Exterior nostrils double; 7. Disproportionate enlargement of the head (> 20% of body length in all cases).
Balaenidae: Right whales Mysticete families: 2-4 species; All species and populations in dire peril except for the southern right whale; Feed primarily on small zooplankton.
Mysticete families: Balaenidae: Right whales Enormously disproportionate head typically one-third of body length; Highly convex upper skull surface; Thick blubber layer; Feed by skimming; Lack throat pleats.
Mysticete families: Neobalaenidae: Pygmy right whale 1 species; Rare and poorly known to science; All observations in the southern hemisphere; Upper skull surface convex, mandibles often convex as well; Ribs unusually large and numerous.
Mysticete families: Balaenopteridae: Rorquals 6-8 species; Many, but not all species and populations in dire peril; Richard Ellis Feed primarily on larger zooplankton (especially krill) or on schooling fish.
Mysticete families: Balaenopteridae: Rorquals Head proportionately smaller than in balaenidae; Upper skull surface typically flat; Blubber layer typically thinner than in balaenidae; Feed by lunging; Extensive development of throat pleats. Minke whale Blue whale Blue whale
Mysticete families: Eschrichtiidae: Gray whale 1 species; Four populations in the northern hemisphere: Two are extinct, one is critically endangered, and one is large and relatively stable; Several feeding strategies (skimming or midwater feeding for zooplankton, or bottom feeding for benthic crustaceans). Uko Gorter Illustrations/American Cetacean Society
Mysticete families: Eschrichtiidae: Gray whale Skull morphology intermediate between balaenidae and balaenopteridae; Baleen short and light colored; More heavily parasitized by epibiota than any other cetacean. Uko Gorter Illustrations/American Cetacean Society
Sirenians: General characteristics I: 1 1. Loss of rear limbs and pelvic girdle; 2. Modification of front limbs as flippers; 3. Propulsion by caudal spine; 4. Development of caudal flukes or paddle lacking skeletal elements. 3 4 2 Text reading reference: Section 1.2.3
Sirenians: General characteristics II: 5. Loss of pelage; 6. Development of subcutaneous blubber layer; 7. Retention of terminal nostrils.
Sirenians: General characteristics III: 8. Simplification of teeth for mastication of plant matter; 9. Herbivorous diet and associated digestive anatomy and physiology; 10. Multilobed prehensile lips.
Sirenian families: Trichechidae: Manatees Three extant species: West Indian Manatee West African Manatee Amazonian Manatee; Skull with slight ventral deflection; Tail is paddle-shaped Migratory, and able to utilize both fresh and salt water habitats.
Sirenian families: Dugongidae: Dugongs One extant species: Dugong; Forage on seagrasses on the sea bottom Skull with substantial ventral deflection; Tail is fluke-like resembling that of the cetaceans; Fully marine species with Indo- Pacific distribution.
Sirenian families: Hydrodamalidae: Sea cows One modern species, Steller s sea cow, hunted to extinction in 1767; Foraged on kelp canopies at the sea surface, and on algae in rocky intertidal habitats Skull with minor ventral deflection; Tail was fluke-like resembling that of the cetaceans;
Sirenian families: Hydrodamalidae: Sea cows (Continued) Fully marine species with distribution limited to the Commander Islands of the Russian Far East. Lacked wrist bones and digits (unique among the marine mammals; Probably unable to dive (also unique); Included in the family Dugongidae by some taxonomists.