Sun Compass

Question 1

Theory: Time memory is used to remember where food was
Why was this rejected?

Answer 1

There was proof that a circadian clock is used instead (Continuous clock goes against encoding specific times of day)

Question 2

Amphipod jumping direction experiment
- When released close to water (La Jolla)
- When released close to water in La Jolla (from Santa Barbara)
- When released on dry land (Del Mar)
- W/out sun
—No landmarks—
- Released near water on North Island (from Del Mar)
- Released at North Island w/ 90° (6 hr delay) shift (from Del Mar)

What cues are used?

Answer 2

• Jump towards land
• Jump towards land in La Jolla
• Jump towards water
• Jump in any direction
  ——
• Jump towards land in direction of Del Mar
• Jump in direction according to its circadian clock

Local cues and sun + circadian clock

Question 3

Talitris saltador collected in Italy and released on a beach in Brazil
- Were released at 10 AM Italy time and would usually go SW (60° clockwise)
- Sun is slightly NE in Brazil at 6:30 AM local time

Answer 3

Instead went SE based on position of sun from Italy

Question 4

Bees
Waggle dance
- Distance of food from hive is correlated with what in the dance?

Answer 4

Communicate distance, direction, quality; and time of food availability
Waggles show direction w/ respect to the sun (Up in vertical honeycomb is towards sun) - Figure 8 shows diff locations depending on wing and abdomen vibrations

• Duration of waggling run
• Duration of return run
• Duration of sound
• Number of waggles

Question 5

Reasons for migration
What do birds use to determine direction during migration

Answer 5

Reasons: Lack of food/water availability, reproduction, temperature

Cues: Environmental cues and sun

Question 6

Starling migratory study
- Birds were in cage during migratory season and saw wild birds flying outside

What happened when:
- It was sunny
- It was cloudy
- There was a mirror reflecting direction of sun

Answer 6

Sunny -> Huddled in SW corner of cage
Cloudy -> Were dispersed
Mirror -> Huddled in NE (opposite) corner of cage

Question 7

Starling migratory study
- Birds put in cage and step on ink that track where they go towards food in a funnel depending in artificial light

What happened when:
- Light was off
- Light moved 15° per hour
- Light’s position stayed constant

Answer 7

Light off -> Error in angle
15° per hour -> Starling compensated 15° every hour (Shows birds don’t see sun as just a stationary object)
Constant -> Moved 15° counterclockwise per hour

Question 8

Monarch butterfly migratory study
- Wire attached to butterfly in chamber w/ fake sun

What happened with a:
- 6-hour shift (90°)

Answer 8

Butterfly also shifted 90°

Question 9

What clock proteins do monarch butterflies have?
How many clocks do they have?

Answer 9

Cry, Per, Tim
Two -> One on each side (antenna) with a central clock (brain) to create even orientation

Question 10

Monarch butterfly antenna study (Sun compass orientation)
- One antenna removed
- Two antennas w/ one phase disrupted
- Removing the disrupted antenna

Answer 10

Still able to orient to sun

Starts confusion and freerunning
- Antennas’ signals won’t be synced

Confusion will be fixed