Marine Mammals Flashcards
What is Laurasiatheria?
A major clade of mammals including carnivorans, hoofed mammals, bats, and pangolins.
How are carnivorans classified within Laurasiatheria?
Carnivorans are split into two branches:
- Feliformes (cat-like): Includes cats, hyenas, civets, and mongooses.
- Caniformes (dog-like): Includes dogs, bears, seals, sea lions, raccoons, skunks, and mustelids.
What are key characteristics of carnivorans?
Carnassial teeth for slicing meat.
Compressed, sharply pointed claw bones (unguals), often retractable.
What distinguishes feliform carnivorans?
Tend to be adapted for climbing and ambush predation, with enlarged, fully retractile claws (except cheetahs) and strong specialization for carnivory.
Do feliforms include aquatic or marine species?
No, most are terrestrial or arboreal, though some, like the water mongoose and otter civet, forage in shallow water.
What are notable adaptations of cats (Felidae)?
Reduced molars, specialized for carnivory.
Jaguars (Panthera onca) are robust swimmers and hunt in aquatic environments but are not aquatic species.
What characterizes caniform carnivorans?
Includes a mix of long-legged predators (e.g., dogs, wolves) and smaller omnivores or small-mammal predators.
Herbivory has evolved at least three times.
Which caniform groups are aquatic or amphibious?
Pinnipeds (seals, sea lions, walruses): Fully aquatic.
Mustelids (e.g., otters): Amphibious predators with adaptations for water.
How did dogs (Canidae) evolve?
Ancestral dogs were small, fox-like omnivores. Larger, cursorial predators evolved during the Miocene with the rise of grasslands and large hoofed mammals.
What are key adaptations of otters for aquatic life?
Dense, fine fur for insulation (sea otters have 125,000 hairs/cm²).
Webbed digits for propulsion and sensitive whiskers for prey detection.
Streamlined bodies and high-positioned sensory organs (eyes, nose, ears).
How do sea otters (Enhydra lutris) differ from other otters?
Fully aquatic, diving to 100m for prey like crabs, mollusks, and urchins.
Use tools (rocks as anvils) to break open hard shells.
The heaviest otter, reaching up to 45kg, with a life centered entirely in coastal waters.
What ecological role do sea otters play?
Control sea urchin populations, preventing overgrazing of kelp forests. Loss of otters leads to trophic cascades, impacting marine ecosystems.
What is the evolutionary history of bears?
Evolved from raccoon-like ancestors in the Late Eocene. Early bears were omnivorous; some later specialized as predators or herbivores.
What adaptations do polar bears (Ursus maritimus) have for aquatic life?
Long necks for pulling prey and enhanced field of vision.
Hollow, insulating fur and thick blubber.
Partially webbed digits and powerful paddling ability for long-distance swimming (up to 687km).
How has climate change affected polar bears?
Declining sea ice reduces their ability to hunt seals, leading to thinner bears and lower cub survival rates. They are also heavily polluted with bioaccumulated chemicals.
