Course evaluation submission:

Transcription

1 Course evaluation submission: 1. Forms to pick up today: a) one yellow form for overall course comments; b) one form A to evaluate Glenn; c) one form H to evaluate your TA. 2. Return forms to Sophie: At the end of the Final Examination (make sure your name gets checked off ); points added to course grade if forms are returned at the Final Examination.

2 Final examination 15 short answer questions; Similar format to 2009 final examination (see course website); ~75% of questions from second half of term, ~25% from first half; Wednesday, 9 June 2010, 2:30 4:20 pm, rm 107 FSH

3 Synopsis of responses: Low stakes writing, assignment #3: The question: During class discussions about "depensation" (the low per capita birth rates that sometimes are observed in small populations with abundant food resources), it was noted that one cause of this condition is that in small populations, location suitable mates for reproduction may be difficult if the population is widely spread and has low density. In the 1960s it was noted that blue whales were both rare and widely spread, due to decades of excessive harvest by the commercial whaling industry. However, since that time blue whale populations have grown steadily, albeit slowly. The data suggest that location of mates has not been a major problem despite the low numbers and broad dispersion in blue whale populations. Suggest a plausible mechanism by which mate location can occur despite the low numbers and broad dispersion in blue whale populations.

4 Synopsis of responses: Low stakes writing, assignment #3: Summary of responses: 37 students responded, with a total of 89 suggested answers. Most popular responses: 1. Aggregation at traditional breeding locations at traditional times each year: Use of high-intensity vocalizations that travel across long distances: 28* 3. Aggregation at locations of high productivity that are used for feeding as well as breeding: 8 4. Adult males and females form lifelong pair bonds and remain together constantly, allowing immediate contact without search during breeding season: 4 5. Prolonged period of estrous and reproductive competency, allowing mating whenever adult males and females encounter one another: 3 6. Use of echolocation to find mates: 3 *One student indicated that he learned this from reading the outside of a CrackerJack box

5 Synopsis of responses: Low stakes writing, assignment #3: Summary of responses: 37 students responded, with a total of 89 suggested answers. Most popular responses: 1. Aggregation at traditional breeding locations at traditional times each year: Use of high-intensity vocalizations that travel across long distances: 28* 3. Aggregation at locations of high productivity that are used for feeding as well as breeding: 8 4. Adult males and females form lifelong pair bonds and remain together constantly, allowing immediate contact without search during breeding season: 4 5. Prolonged period of estrous and reproductive competency, allowing mating whenever adult males and females encounter one another: 3 6. Use of echolocation to find mates: 3 *One student indicated that he learned this from reading the outside of a CrackerJack box

6 Synopsis of responses: Low stakes writing, assignment #3: Summary of responses: 37 students responded, with a total of 89 suggested answers. Other suggestions (one response each): 1. Travel in small mixed-sex packs year-round to ensure breeding success when breeding season occurs; 2. Male-biased sex ration to ensure that any animal encountered by a male is likely to be a female; 3. Sperm storage capability by females, allowing mating on any encounter with a male, with storage to delay fertilization until the appropriate time/season; 4. Highly sensitive chemoreceptive abilities to facilitate location of mates; 5. Great size of blue whales makes them easy to find; 6. Extremely high maternal investment in calves to ensure that every calf has a high survival probability; 7. Large litter sizes; 8. High degree of physiological synchronization in male and female breeding cycles; 9. Maintain aggregations year-round; 10. Climate change is producing better environmental conditions for blue whale reproduction.

7 Fish 475: Marine Mammalogy Acoustics 4 June 2010 Text reading reference: Chapter 6 Course website:

8 Frequency or pitch 1 OceanLink

9 Sound pressure level (aka amplitude or loudness ) 2

10 3 Units of sound pressure level Pascal (P): Pressure resulting from a force of one Newton applied to an area of 1 m 2 Typically expressed as micropascals (μp): 1 μp = 1 x 10-6 P

11 Sound waveform representations 4

12 Convention for expressing sound pressure levels: Decibels (db) 5 Decibel: 1 db = 20[log 10 (P/P 0 )] Where: P 0 = 1 μp for sounds measured in water P 0 = 20 μp for sounds measured in air [Dimensionless!]

13 Speed, frequency, and wavelength 6 Typical sound speeds (c): Example at sea: In water: c = ~1500 m/s In air: c = ~340 m/s (@ 1 atm) Relating the variables: If f=20 Hz (lower frequency limit for human hearing), then λ = 75 m! λ = c/f Where: λ is wavelength, & f is frequency

14 7 Hearing capabilities of marine mammals Methods of measurement: 1) Auditory evoked potentials; 2) Behavioral responses; 3) Other approaches

15 8 Measuring auditory evoked potential Determination of neurological discharge in response to auditory stimuli of varying frequency and sound pressure levels Ted Cranford

16 Measuring auditory evoked potential 9 Ted Cranford

17 Behavioral observations 10 Pt. Defiance Zoo & Aquarium UC Santa Cruz

18 11 Other approaches to measurement of auditory acuity Monitor for changes in heart rate in response to auditory stimuli of varying frequency and sound pressure level J. Miksis

19 12 Ted Cranford

20 13 Audiograms: Cetaceans and pinnipeds University of Rhode Island

21 14 Audiograms: Sirenians University of Rhode Island

22 Hearing anatomy: The terrestrial mammalian model 15 Auditory canal open to the exterior; Tympanic membrane well tuned to respond to airborne compression waves

23 Hearing anatomy: Internal ears of marine mammals are consistent with terrestrial ancestry 16 Internal ear image from a blue whale D. Ketten, WHOI National Geographic Society

24 17 Hearing anatomy: Adaptations in the odontocetes Ear canal does not open Externally; Sound transmitted to the auditory receiving area of the skull by way of the lower jaw, mandibular (acoustic) window, and specialized lipid bodies ( fatty channels ).

25 Hearing anatomy: Adaptations in the odontocetes 18 Killer whale Mandibular window Risso s dolphin Bottlenose dolphin

26 19 Hearing anatomy: Adaptations in the odontocetes D. Ketten, WHOI

27 CAT scan of dolphin head 20 Ted Cranford

28 21 Sound production in the odontocetes J. Van der Toorn

29 22 Sound production in the odontocetes Actually, I don t make noise through my mouth! J. Van der Toorn

30 Sound production in the odontocetes 23 Key structural advances: 1) Phonic lips/dorsal bursa complex; 2) Acoustic melon; 3) Concave upper surface of skull; 4) Vestibular sacs. OceanLink

31 Sound production in the odontocetes 24 Vestibular air sacs: Allow air to be moved rapidly across the phonic lips, providing the vibrations that generate outgoing sounds, without the need to exhale. ThinkQuest 98

32 Sound production in the odontocetes: CAT scan of sperm whale head 25 Ted Cranford

33 Sound production & reception in the odontocetes 26 University of Rhode Island

34 27 Echolocation in odontocetes University of Rhode Island

35 Echolocation in odontocetes 28 Echolocation clicks: 1) High frequency: khz (λ=~7-15 mm); 2) Most effective at ranges of m, and for target sizes of 5-15 cm; 3) Absorption loss significant beyond 200 m range.

36 Echolocation in odontocetes 29 Why high frequencies for clicks? Since lower frequencies travel much farther (lower rate of absorption), why not click at lower frequencies? Key reason: Target resolution: Higher frequency echos provide much more information about the target Example: A bottlenose dolphin can discern a B-B from a kernel of corn at a range of 15 m in total darkness NOAA

37 Echolocation in odontocetes: Some audio examples 30 NOAA