Marine Mammal Taxonomic Groups Flashcards
What are some characteristics of marine mammals?
- Breath air through lungs
- Warm-blooded
- Bare live young
- Suckle their young
What are the four taxonomic groups of marine mammals?
- Pinnipeds
- Sirenians
- Otters
- Cetaceans
What are some key differences between mammals living in water and air
- Inability to exchange gases at all times
- Increased rate of heat loss
- Relative weightlessness (results in larger body size)
- Greater resistance to movement
- Changed characteristics of sound propagation (sound travels faster and farther in water)
- Low-light conditions
What are the 3 different orders of marine mammals?
- Carnivora
- Sirenia
- Cetacea
What is the most diverse order of marine mammals?
Cetacea
(90 species)
What are some characteristics of the order Cetacea?
- Streamlined body shape
- Blubber
- No pinnae
- No hind limbs only front limbs (flippers)
- Intra-abdominal testes (within body cavity)
- Mostly hairless
- Horizontal flukes (tail flippers)
What are the two sub-orders of Cetaceans?
- Odontoceti
(Dolphins and Porpoises) - Mysticeti
(Baleen whales)
What are some characteristics of the sub-order Odontocetei?
- Teeth
- Single blowhole
- Asymmetrical cranium
- Melon
- Large size range between species (ex: small porpoises vs sperm whale)
What are some characteristics of the sub-order Mysticeti?
- Baleen plates
- Paired blowholes
- Symmetrical cranium
- Must be large in order to filter feed
Not a large range of body size like Odontesites
What is a key difference between dolphins and porpoises?
The melon
- Porpoises: melon extends to apex of snout
- Dolphins: melon ends before snout
Does body size reflect prey size in Mysticetes?
No, baleen does
- Short baleen = large prey (fish)
- Longer baleen = small prey (plankton)
What is the purpose of rorquals?
Allows whales to extend buccal region (take in large quantities of water)
What are some morphological adaptations of Mysticetes?
- Baleen
- Enlarged buccal cavity (throat region)
- Mandibles joined by flexible ligament
- Throat grooves (rorquals)
- Cavum ventrale (muscles)
What are the three filter feeding strategies of Mysticetes?
- Skimmers
- 1 step - Gulpers
- 2 steps - Sifters
- 2 steps
Describe the foraging behavior of skimmers?
Ram filtration
- Baleen bristles filter out plankton as water flows through
- Whale uses tongue to push out water through baleen
- Ex: Right whale
Swim with their mouths open
Describe the foraging behavior of gulpers?
Step 1: Take in gulp of water (engulfs dense patch of prey)
Step 2: Force water out through baleen
- Ex: Rorquals
Describe the foraging behavior of sifters?
- Bottom feeders
Step 1: Take in sediments from bottom of water column
Step 2: Force sediments out, keep nutrients - Ex: Gray whales
What are the two sub-orders of the order Carnivora?
- Pinnipedia
- Fissipedia
What are the three families within the sub-order Pinnipedia?
- Otariidae
- Phocidae
- Odobenidae
What is the family within the sub-order Fissipedia?
Mustelidae
Describe the morphology of Pinnipeds
- Streamlined body shape
- Hind flippers
- Homodont cheeck teeth (teeth are all about the same shape)
Describe the morphology of Phocidae
- Pinnae: Lacking
- Testes: Internal
- Upper canines: Normal
- Hind flipper mobility: No
- Ex: True seals
Describe the morphology of Otariidae
- Pinnae: Present
- Testes: Scrotal
- Upper canines: Normal
- Hind flipper mobility: Yes
- Ex: Eared seals
Describe the morphology of Odobenidae
- Pinnae: Lacking
- Testes: Internal
- Upper canines: Tusks
- Hind flipper mobility: Yes
- Ex: Walrus
Why is the breeding behavior of pinnipeds unique among marine mammals?
They are tied to land for breeding
Describe the morphology of marine otters
- Streamlined body shape
- Short legs / webbed feet
- Dense fur coats
- Heterodont dentition (teeth have different forms and functions)
Describe the morphology of sirenians
- Streamlined body shape
- Blubber
- Intra-abdominal testes
- Dorso-ventrally flattened tail fluke
- Axiliary mammary glands
- Sparse hair
- Pachyostotic bones (bones = dense +compact)
- Ex: Mantees, Dungongs, Stellar’s sea cow