Lecture 4 Flashcards
Study for the midterm and final
What is the Mandible and what is it used for?
- Lower Jaw
- is ued to obtain food to the digestive tract
What is the maxilla?
- The upper jaw
What is unique about the mandible in Cetaceans?
Aside from food, it acts as an organ for sound reception
Why is a wide range of adaptation and variation in marine mammal mandible favorable?
- allows an extensive range of prey animals that are used for food
What are the three levels of the ocean where food sources can be found?
- Pelagic (open water)
- Demensal (on/near bottom)
- Benthic (bottom sediment)
List the type of teeth found in marine mammals and their single letter abriviations
Front
- I = incisors (small teeth in front for gripping)
- C = Canines (Powerful, puncturing teeth found in pairs)
————————————————————-
Back
- PC = post canines (back of the mouth)
OR
- P = Premolars (Back of the mouth, cut, shear, and crush)
- M = Molars (Back of the mouth, cut, shear, and crush)
How do subscripts and superscripts work when labeling teeth
- Superscript = upper jaw (Maxilla)
- Subscript = lower jaw (Mandible)
Generally how many teeth do Pinnipedia have?
- Usually between 18-38 teeth
- Otariidae (eared seals 34-38 teeth)
- Phocidae (earless seals 22-36 teeth)
- Odobendiae (walrus 18-24 teeth)
What are the tusks used for in Walrus and how does the function differ between gender?
- Tusks continually growing canines
- Males = Display
- Females = Defense
- Both = used to disturb bottom while searching for prey
What are some examples of tooth variation in Pinnipedia?
- Crabeater seal - teeth designed to strain krill
- Leopard seal - long sharp to capture seal/penguins
How many functional teeth do Manatees have and how do they obtain new teeth and diet?
- 5 to 7 functional teeth
- 20 to 30 teeth during lifetime
- Teeth are replaced from rear to front
- Diet = vegetation
Describe Dugong’s dentition and diet
- Have fixed number of teeth
- Both sexes develop small tusks
- Tusks are not used as weapons
- Diet = vegetation
Describe Ursidae (polar bear) Dentition and diet
- Polar bears have 38 to 42 teeth
- Premolars/molars sharper than other bears
- Diet = seals
Describe Mustelidae (sea otters) Dentition
- approximately 32 teeth
- Reduced number of lower incissors
- Modified molars (larger and harder)
Describe Odontocete (toothed) whales dentition
- shape of mouth, jaw, and teeth vary between families
How do you differentiate between species of Cetaceans?
- Number of teeth
Describe Narwhals Dentition
- Long tusk (usually left canine tooth)
- Erupts anteriorily from head
- Reaches up to 3m
- males MAY have 2 tusks
- females may have tusk, but much shorter
- Sexual display ONLY, not fighting
- Spiral growth
Describe Phocoenidae (Porpoises) dentition and diet
- Equal number of teeth in upper AND lower jaw
- From 15 to 30 teeth
- Diet = Small pelagic herring anchovies, small fish close to surface
Describe Delphinidae (Dolphins) dentition and diet
- Large range of teeth numbers
- May vary from 0/2 to 65/58
- Teeth connical shape
- Diet = normally cephalopods, fish
Describe mysticetes (baleen) whales dentition
- adult have NO TEETH
- 2 rows of baleen plates
Describe Baleen function and how it grows
- Baleen plates strong and flexible
- Plates grow continuously
- Covered by sheath of keratin filled cells
- Acts as a filter to hold in prey but filter water out
How big of a difference can the Baleen be within Mysticete family?
10-fold difference between species
How does the skull shape influence behavior?
Skull shape reflects how they hunt for food
What are the parts of the Skull that is shared across marine mammals?
- Frontal Bone
- Orbit (eye location)
- Area of Turbinates (nasal area)
- Maxilla (upper jaw)
- Mandible (lower jaw)
- Zygomatic Arch
- Temporal bone
- Parietal bone
What is different between the skulls of marine mammals?
- Bones are the same
- Shape of the bones differ
