Fish 475: Marine Mammalogy

Transcription

1 Fish 475: Marine Mammalogy Taxonomy (continued) Friday, 2 April 2010 Amanda Bradford Course website:

2 Odontocete families: Kogiidae: Pygmy and dwarf sperm whales Teeth only in lower jaw; Extreme asymmetry of skull; Formerly included in the physeteridae; Small, rare, and poorly known to science.

3 Odontocete families: Delphinidae: Dolphins Most diverse of the marine mammal families species; Most species have prominent falcate dorsal fin, pronounced rostrum, and obvious acoustic melon above the skull; Typically live in long-term, stable, genetically-based social groups.

4 Odontocete families: Delphinidae: Dolphins Tooth number variable, with many teeth in most species; Bottlenose dolphin Teeth conical, in contrast to those of the Phocoenidae; Skull asymmetry is typically slight. Pantropical spotted dolphin Risso s dolphin

5 Odontocete families: Phocoenidae: Porpoises Widespread and often abundant; 6 species currently recognized; Social systems either absent or less strongly developed than in the delphinidae; Most species and populations utilize coastal habitats.

6 Odontocete families: Phocoenidae: Porpoises Teeth generally numerous and spoon shaped easily distinguished from teeth of delphinids; Dall s porpoise Rostrum typically more blunt than delphinids; Harbor porpoise Asymmetry of skull is minimal; Dorsal fin generally triangular rather than falcate

7 Odontocete families: The river dolphins: Boto (Iniidae) Platanistidae Iniidae Lipotidae Pontoporiidae La Plata River dolphin (Franciscana; Pontoporiidae)

8 Odontocete families: The river dolphins: Boto (Iniidae) Platanistidae Iniidae Lipotidae Pontoporiidae La Plata River dolphin (Franciscana; Pontoporiidae)

9 Odontocete families: The river dolphins: Extremely elongated rostra; Indus River dolphin Numerous teeth; Large sagittal crests in some cases; Poor eyesight; La Plata River dolphin Extreme development of acoustic capabilities; Relict habitats.

10 Mysticeti: The baleen whales About 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

11 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.

12 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).

13 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.

14 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.

15 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.

16 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.

17 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

18 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

19 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