Unit 3 (Exam 3)

What are the 7 types of behavior? Know Examples.

1. Foraging

2. Sexual

3. Predation avoidance / defense

4. Migration

5. Competition

6. Parental

7. Social

What is foraging?

the act of looking for, collecting, and consuming food

What are the mechanisms of foraging in odontocetes?

• highly derived mandibles

• suction feeding in some species

• orofacial morphology

What are odontocetes using their teeth for?

Not really chewing, but for echolocation

• also used to grasp onto their prey and drag it across the seafloor until it breaks up into smaller pieces

• if you look into a stomach, you will see whole chunks of food or whole fish

• can also choke often on food, can tell from fish being stuck in their throats

What are the mechanisms of foraging in mysticetes?

• baleen

  • food particles get stuck in this mesh when the water gets filtered out through this baleen

• balaenids’ maxilla has higher arch

What are the four main foraging methods?

The four main methods are divided by taxa:

1. Engulfment (Balaenopteridae)

2. Benthic suction (Eschrichtiidae)

3. Skim feeder (Neobalaenidae)

4. Skim feeder (Balaenidae)

Who has the largest baleen (ranked)?

1. Skim feeders

2. Engulfment feeders

3. Benthic suction feeders

What are the mechanisms of foraging in pinnipeds?

• Some employ suction feeding

  • short, wide rostra and scoop-like jaws

• similar skull and tooth structure to dogs

• crabeater and leopard seals use filter feeding to eat krill

  • use cheek teeth as sieve

What are the mechanisms of foraging in the walrus?

• walrus have vastly different skulls

  • maxillary bones enlarged for tusks

  • short, wide rostrum for benthic feeding

• use tusks to pull out of water; not for feeding

What are the mechanisms of foraging in sirenians?

• unique - herbivores

• pronounced and expanded premaxilla

  • even more so in dugongs

• dugong rostrum turned 70° downward

  • manatees ~ 26-30°

• only obligate marine mammals to chew!

  • manatees have replaceable teeth

  • dugongs have peg-like teeth

What are the mechanisms of foraging in sea otters?

• use forepaws to dig clams and pry urchins off rocks

• sea otter teeth are adapted for crushing

• short, blunt skulls

• increased occlusal surface

• modified jaws muscles

What are the mechanisms of foraging in polar bears?

• completely carnivorous

• large masticatory muscles and teeth

• reduction in molar size and blades of carnassial teeth

• skulls more different than terrestrial bears than previously thought

Difference between strategy vs tactic? Examples?

Strategy — genetically based decision rule that results in the use of certain tactics (what they can do physiologically)

• humpback → baleen

• orca → agility / body size

Tactic — used to pursue a strategy and include behaviors (HOW they can use this physiology)

• humpback → bubble-net feeding

• orca → beaching

What are some foraging tactics, what strategy drives each tactic?

• stalking and ambushing

  • morphology and stealthiness (polar bears)

• prey herding / manipulation

• prey debilitation

• tool use

  • strategy? (sea otters and dolphins)

• benthic foraging

  • strategy? (dolphins)

• batch feeding

• kleptoparasitism and scavenging

group foraging tactic:

• some just aggregates of individuals

• others are cooperative groups

  • prey sharing

• can be difficult to determine

filter feeding tactic:

• all baleen whales, some pinnipeds

  • crabeater, leopard, and Antarctic fur seals

• Pinniped adaptations not as extensive as mysticetes

  • cusps

what are the three types of filter feeding found in mysticetes?

1. suction feeding (gray whales)

2. continuous ram feeding (right and bowhead whales)

3. lunge feeding (rorquals)

diets (specialists vs. opportunists)

• specialists have a narrow, specific diet

  • sperm whales, sirenians

• opportunists have a much broader diet

  • killer whales, bottlenose dolphins, humpbacks

specialists vs opportunists: who is more sensitive to environmental change?

overall, specialists are

• but if you’re comparing a sperm whale vs a humpback whale, the sperm whale may be a specialist but squid are down deep and SO abundant, while humpbacks eating plankton communities may be more vulnerable

• actually, copepods today have less nutritional value than copepods historically → results in fitness consequences for the animals

what can diet tell us?

how do we figure out diet in cetaceans / marine mammals?

• stomach content analysis

  • pros: detailed, by volume/weight

  • cons: time-frame, digestion rates, depredation (decomposition stage), body availability, empty stomach (starving), resource heavy(ish), snapshot

    • how do we know if it’s something that the cetacean ate that is what killed it? did it eat something weird? are you representative of the population?

    • bycatch are more representative of the population because they didn’t wash up dead from something else

What are stable isotopes? Why do we use them?

Definition:

• naturally occurring isotopes

• pass between prey and consumer

• retention time based on tissue type

Differences between carbon and nitrogen isotopes?

Carbon

• represents inshore/offshore

• indicates sources of primary productivity

• known gradients in marine environment

Nitrogen:

• indicates trophic level spot

• may occur in marine gradients

How to get tissue samples from live, swimming dolphins?

• remote biopsy sampling (guns or crossbows)

  • prey: sampling or fish markets