Cetaceans

Question 1

Pakicetus

Answer 1

Primary land animals (Thewissen et al, 2001)

Question 2

Pakicetus bones

Answer 2

Limb bones are osteosclerotic = aquatic habitats

Heavy bones provide ballast

They could stand in water, almost totally immersed, without loosing visual contact withthe air

Question 3

What is the the involucrum in cetaceans?

Answer 3

The medial tympanic wall is inflated

Question 4

What is the tympanic plate in cetaceans?

Answer 4

Thinning of the lateral tympanic wall

Question 5

Artiodactyls walls

Answer 5

The median and lateral tympanic walls are more similar in thickness

Question 6

Rodhocetus body

Answer 6

Is an Eocene whale that had short limbs with long hands and feet that were probably webbed.

It had a sacrum that was immobile with four partially fused sacral vertebrae

It possesses land mammal characteristics = evolutionary of land to sea

Question 7

Thermoregulation

Answer 7

Aquatic environment is a heat sink

Large brain needs lots of heat- in built thermogenic system

Large appendages act as radiators

Question 8

Do animals feel cold like humans?

Answer 8

Skin is innovated with temperature-sensing nerve cells

They have the ability to sense temperature

They respond to temperature stimuli

Question 9

Thermal properties of water

Answer 9

Specific neat per unit volume X 3,400 that of air

Thermoconductivity is x25 that of air

Question 10

Polar oceanic water temperature

Answer 10

Can get as cold as -2°C

Question 11

Seawater in temperate or tropic temperature

Answer 11

Can drop as low as -1°C if you go deep enough below the surface

Question 12

How do endothermic marine mammals deal with it?

Answer 12

One way of minimizing heat loss is to have a relatively low surface area-to-volume ratio:

A small amount of skin= across which heat is exchanged within the environment

Large volume of body tissue-which generates heat

Larger animals send to have lower surface area-to-volume ratios

Question 13

What is blubber?

Answer 13

Excellent insulation in the form of fur or blubber

Animals that spend most their time in water rely on more blubber

Question 14

Metabolic activity - killer whales

Answer 14

Basic metabolic rate vs body mass for killer whales

Killer whales have significantly higher metabolic rate than a terrestrial mammal with similar mass

Question 15

Highlights of cetacean brains

Answer 15

Highly developed neocortex

High degree of foliation

High degree of folding associated with neocortex

Question 16

Imitation behaviour

Answer 16

Important type ot social leaving that car readily lead stable cultures

Question 17

Social motor imitation - study in dolphins

Answer 17

Demonstrated first by dolphins= allowed to see each other but not the trainers

The demonstrator dolphin was instructed to perform a behaviour

Then the imitator had to mimic the behaviour

Both dolphins performed the behaviour

Question 18

Four challenges of whale vision

Answer 18

Pressure
Optic refraction of surrounding environments
Cold
Light levels

Question 19

Snarks vision

Answer 19

Accommodation due to lens displacementnot distortion
Displacement may be achieved via intra ocular pressure changes
Achieved via axial displacement of the ocular globe using retractor/protractor muscles

Question 20

Six facts about snark vision

Answer 20

Photoreceptors sensitivity is shifted towards Bluewave lengths
Vision is monochromatic
Tapetum are present
Highly vascularised
Thickened sclera and cornea
Large extrinsic ocular muscles

Question 21

Oscine (songbird) birds and humpback wales

Answer 21

Use song complexity to assess male fitness, whereas the role of complexity in humpback whale song is uncertain owing to local population-wide conformity to one song pattern

Question 22

Song patterns of humpback whales

Answer 22

Depends on where the live, with populations inhabiting different ocean basins normally singing singing quite distinct songs

They would sing a consistent song year after year

Question 23

When do male humpback whales?

Answer 23

Sing while migrating to and from their breeding grounds, and when they are at the grounds themselves

Song is thought to be a form of sexual display/courtship, but it is not known whether its main purpose is to repel other males or to attract females

Question 24

Males in same population

Answer 24

Produce the same song, which changes through time and all singers maintain the changes, implying that there is a cultural transmission and evolution as in some bird songs

Question 25

Ocean basin

Answer 25

Songs across an ocean basin are broadly similar-differences increase with distance- but populations in different oceans separated by continents have apparently unrelated songs

Question 26

Four main components of echolocation

Answer 26

Propagation
Focusing
Reception
Interpretation

Question 27

What is focusing (melon)?

Answer 27

Low density lipids (oil filed) = acoustic lens
Similar density to surrounding water-less refraction

Fine adjustment of beam focus according to target distance

Question 28

Is there a relationship between sound and prey capture? Miller et al (2004)

Answer 28

During foraging dives, sperm whales produce long series of regular clicks at 0.5-2s intervals / interspersed with rapid-click buzzes called ‘creaks’

Using rags that measured sound, depth and orientation to test whether the behaviour of diving sperm whales support the hypothesis that creaks are produced during prey capture

Sperm whales spent most of their bottom time within one or two depth bands, apparently feeding in vertically stratified prey layers

Question 29

Predators and foraging decisions

Answer 29

Based upon sensory into about resource availability

Sperm whales employ a directed search behaviour by modulating their overall sonar sampling with the intention to exploit a particular prey later.

They forage opportunistically during some descents, well actively adjusting their acoustic gaze to track different pray

Whilst foraging within patches sperm whales adjust their clicking rate both to search new water volumes as they turn to match the price distribution