Lecture 4a: Skull and Teeth

Question 1

1) What is the proper name for the lower jaw
2) describe what is it used for in marine mammals?
3) what bone does it articulate with?
4) what bone is it in contact with?

Answer 1

1) Manidible
2) to obtain food to enter the digestive tract
3) with the skull
4) maxilla (upper jaw)

Question 2

What can the shape of the skull reflect? Contrast this between a cetacean with a short blunt skull vs. Long narrow skill)

Answer 2

Exhibit the maker of how they hunt or forage for their food becuase it acts as a organ for sound reception

Question 3

Pelagic

• what two areas can you find pelagic fish and define each
• decried the 4 main pelagic zones and their more common names

Answer 3

Inhabit the water column (Not bottom or shore)

• coastal (up to depth 655 ft; above continental shelf)
• oceanic (below continental shelf)

Epipelagic = sunlight 
mesopelagic = twilight
Bathypelagic = midnight
Abyssophelagic  = lower midnight

Question 4

Demersal

Answer 4

On or near bottom

Question 5

Benthic

Answer 5

In the bottom

Ie: sediment

Question 6

Skull: frontal bone

Answer 6

Portion of the skull above the eyes and includes the forehead, roof other nasal cavity and roof of the orbits (bony socket) of the eyes

Question 7

Skull: parietal bone

Answer 7

Protects the brain

Forms side and roof of the skull

Question 8

Skull: temporal bone

Answer 8

Forms base and sides of skull

Question 9

Skull: maxilla

Answer 9

Upper jaw bone
- support teeth and palate of skull.
Includes: eye sockets and lower parts and sides of the nasal cavity

Question 10

Skull: orbit

Answer 10

Eye location

- made up of 7 bones which protects, supports, and maximize the function of the eye

Question 11

Skull: Zygomatic Arch

Answer 11

Protects the eye
(Cheek)
- from temporal bone to maxilla
Masseter chewing muscles attaches here

Question 12

Skull: Area of Turbinates

Answer 12

Warms and moistens air

Structure made up of mix cartilage/bone to warm and moisten air

Question 13

Skull: Mandible (lower jaw)

Answer 13

Bone that forms the lower art of the skull (support teeth) and with maxilla the mouth

Question 14

Skull:

Compare shapes and location for sea otter

Answer 14

have really small heads, large zygomatic arch, large area of turbinates, parietal bone is larger, small frontal bone, enlarged maxilla and mandible

They are carnivores that use their teeth in a more diverse fashion for tearing and cracking of food.

Question 15

Skull:

Compare shapes and location for crab eater seal and bearded seal

Answer 15

Crabeater seals are carnivores that use their teeth to strain from the ocean water
Bearded sea are carnivores that use their teeth to capture small fish (flat teeth, gums are worn down; 34 teeth flat and thicker)

Question 16

Skull:

Compare shapes and location for Dolphin

Answer 16

Dolphins are carnivores with teeth that are uniform and conical in shape and used to capture prey
- cannot identify different kinds of teeth

Question 17

Skull:

Compare shapes and location for Manatee/Dugong

Answer 17

• use their teeth for grinding vegataration
  They only have 5 -7 functional teeth
  20-30 teeth/jaw in their lifetime
  Teeth are replaced from the rear

Question 18

1) What structures in marine mammals possibly has the widest range of adaptations and variations in comparison to terrestrial animals?
2) what is the purpose of this?

Answer 18

Mandibles

These adaptations and variations allows for an extensive range of prey animals that are used for food

Question 19

Mandibles & Dentitation: Cetaceans

What is another unique function for the mandible?

Answer 19

It acts as an organ for sound reception

Question 20

Mandibles & Dentition: Odontoceti Whales

How variable are the number of teeth? (In regards to shape, and numbers)

Answer 20

Shape of the mouth, jaw and the number of teeth may vary between families. but the shape of the teeth are similar throughout and teeth numbers are usually used to differentiate

Question 21

Mandibles & Dentition: Odontoceti Whales

What does 15/18 mean?

Answer 21

15 teeth in upper jaw

18 teeth in lower jaw

Question 22

Mandibles & Dentition: Narwhales

What is the unique structure they have? (Give the characteristics)

Answer 22

Long tissue that is from the LEFT canine tooth

• erupts anteriorily from the head
• may reach up to 3 m
• males may have 2 tusks
• females may ahve tusks but much shorter
• these are used for sexual display only! Not for fighting
• grows in a spiral (only species to do this)
• Recently thought to also be a sensory organ (detect salinity, etc)
• rest of ht e teeth are vestigial

Question 23

Mandibles & Dentition: Phocoenidae (porpoises)

1) number of teeth
2) shape of teeth
3) diet

Answer 23

1) equal number of teeth ranging form 15-30
2) flat spatula like teeth
3) coastal species: small pelagic herring anchovies, caplin
Falls porp: squalid, small mesopelagic fresh when closer to surface

Question 24

Mandibles & Dentition: Delphinidae (dolphins)

1) number of teeth
2) shape of teeth
3) diet

Answer 24

1) large range of teeth numbers (0/2 to 65/58)
2) conical in shape
3) normally Cephalopods fish

Question 25

Mandibles & Dentition: Mysticetes whales | Do adults have teeth? What do they have instead

Answer 25

``` No teeth Baleen plates (2 rows) instead that extend centrally from the upper jaw ```

Question 26

Mandibles & Dentition: Mysticetes (baleen) whales what are baleen plates? What is the use of them? What are they covered with?

Answer 26

Are strong yet flexible Grow continuously after being worn down by the tongue and grey Covered by a sheath of keratin filled cells

Question 27

Mandibles & Dentition: Mysticetes (baleen) whales | Does the density of baleen (baleen fibres/ cm2) vary within mysticetes family? If so by how much? (Gray vs. Right whale)

Answer 27

There is a 10 fold difference between species Gray whales: 155/ cm2 and 0.4=0.5 m in length Right whales: more than 350/cm2 and longer than 3m

Question 28

Mandibles & Dentition: Mysticetes (baleen) whales | What forms the filter surface?

Answer 28

The inner fringe becomes entangled and forms this

Question 29

Mandibles & Dentition: Mysticetes (baleen) whales | What are the length differences of baleen and how does it affect feeding techniques?

Answer 29

Right whales have very long and dense baleen so they have narrow rostrum, which makes them have a skimmer technique Grey whales have a gulper technique bc their mouths are wider from the not as long baleen but less dense

Question 30

Mandibles & Dentition: Pinnipedia | Are their teeth all similar in shape? Give an explanation for this?

Answer 30

No, have different types of teeth specialized for specific task as and diets . Ex: crab eater seals (strain like teeth) and bearded seals (flatter and thicker teeth)

Question 31

Mandibles & Dentition: Pinnipedia | Describe how they are referred to?

Answer 31

Incisors, Canines, Post canines, Premolars, Molars

Question 32

Mandibles & Dentition: Pinnipedia | Where are incisors and what are they used for

Answer 32

Front of ht e moth | Small gripping teeth

Question 33

Mandibles & Dentition: Pinnipedia | Where are canines and what are they used for

Answer 33

Beside the incisors, | Powerful, puncturing teeth found in PAIRS

Question 34

Mandibles & Dentition: Pinnipedia | Where are post canines and what are they used for? What are the also referred to as?

Answer 34

Back of the mouth Cut, shear and crush food Premolars or Molars

Question 35

Mandibles & Dentition: Pinnipedia What is the range of numbers they might have in total? (Compare otariidae, phocid, and walrus)

Answer 35

Range between 18-38 teeth Otariids: 34-38 teeth Phocids: 22-26 teeth Walrus: 18-24 teeth

Question 36

Mandibles & Dentition: Pinnipedia What is unique about the walrus? (Characteristics, purposes, sex differences)

Answer 36

Both sexes have tusk Tusks are NOT for feeding Males: use them for display Female: for defence

Question 37

``` Mandibles & Dentition: Pinnipedia What are the shapes of the following teeth: (discuss their diets) 1) Bearded seals 2) Crabeater seals 3) Walrus ```

Answer 37

1) flat and thick teeth used to capture and crush their food. Diet: shrimp, crabs, clams 2) strainer teeth Diet: krill 3) long growing canines - disturb the bottom; thick and flat teeth for crushing shells Diet: bottom feeders: shellfish, small fish, clams

Question 38

Mandibles & Dentition: Sirenia --> Manatee 1) how many teeth in their mouth at any one time? 2) what is unique to manatee teeth and describe this 3) what is their diet consist of?

Answer 38

1) 5-7 functional teeth in the upper and lower jaw --> 20/30 teeth/jaw during their lifetime 2) teeth grow from the rear as they get worn down and fall out 3) Herbivores: vegetation (ie: sea grasses)

Question 39

Mandibles & Dentition: Sirenia --> Dugongs | How do teeth compare to manatee?

Answer 39

They have a fixed number of teeth Both sexes develop small tusks (<15 cm) Tusks are NOT used for weapons Also herbivores

Question 40

Mandibles & Dentition: Ursidae (Polar bears) 1) how many teeth do they have? 2) how specifically do their teeth differ from other bears? Why?

Answer 40

1) 38-42 teeth | 2) premolars/molars are sharper than other bears because more carnivorous and shows an evolutionary adaptations

Question 41

Mandibles & Dentition: Mustelidae (Sea Otters) 1) how many teeth do they have? 2) What if any differences are there compared to other carnivores? Why? 3) describe their diet

Answer 41

1) 32 teeth 2) reduced number of lower incisors; modified molars 3) hard shelled invertebrates