Marine Mammal Sensory & Sound Production Systems MARE 390 Dr. Turner

1. Marine Mammal Sensory & Sound Production Systems MARE 390 Dr. Turner

2. Sound Production, transmission, & reception of sounds produced by marine mammals unique – airborne & waterborne Manner differs between taxa & media Purposes: Communication within species to location of unseen targets with echolocation

3. Sound Propagation Acoustic energy characterized by velocity, frequency, wavelength, & amplitude Human hearing 18 Hz to 15kHz Marine mammal vocalizations above & below < 18 Hz (infrasonic) > 20 kHz (ultrasonic)

4. Sound in Air & Water Sound travels 5X faster in water (1550m/s) than air (340m/s) depending upon temperature & salinity (depth) Why increased capacity for sound production? Poor light transmission & vision in water

5. Functions of Sound Dolphins – large variety of whistle-like sounds; can understand complex linguistics Many sounds used for communication Signature calls identify individuals Loud impulse sounds – debilitation of prey, self-defense, intimidation of conspecifics Echolocation – active detection & identification of a target with sound

6. Acoustic Signal Frequency, duration, & energy level are portrayed as: Spectrogram (frequency with time) Power spectrum (sound pressure levels with time) Frequency spectrum (sound pressure levels with frequency)

7. Acoustic Signal Spectrogram (frequency with time) Power spectrogram (sound pressure levels with time) Frequency spectrum (sound pressure levels with frequency)

8. Use of Sounds Low frequency sounds – attenuate more slowly so good for long distance communication High frequency sounds – attenuate more quickly but have the potential to provide more information on target resolution

9. Mammalian Ear Evolved for detection of sound vibrations in air Amplitude (loudness) determined by the number of hair cells stimulated Frequency (pitch) depends upon the distribution pattern of stimulated hair cells

10. Pinniped Sounds Sounds produced 1° with larynx 2° - teeth & pharyngeal pouches Typical mammalian ear with modifications amplify sound reception engorged with blood during diving

11. Cetacean Sounds Nasal sacs ventral to blowhole produce sounds including whistles & echolocation Monkey-lips or Phonic lips – produce sounds as air is forced through them tweaking end of air-filled balloon

12. Cetacean Sounds

13. Sperm Whale Head

14. Sound Propagation Melon contains low-density lipids which serve as an acoustic lens to create focused directional sound beams

15. Mysticete Rhythms Mysticete larynx possesses structures homologous to vocal folds - are capable of sound generation

16. Mysticete Rhythms (U-fold) in the lumen of the larynx - vibration of edges may generate sounds - walls of the laryngeal sac can serve as a resonant space

17. Sound Reception All cetaceans have good hearing Auditory canal narrow in odontocetes; plugged in mysticetes Glove finger – projection of eardrum into ear canal

18. Odontocete Reception Unique sound reception pathway – jaw Pan Bones - Posterior portions of mandibles, flared, thin to transparency Filled with low density lipid – similar to melon Directly connects with the auditory bulla of the middle ear

19. Odontocete Reception

20. Other Marine Mammals Sea Otters & Polar Bears – no special adaptations; similar to terrestrial mammals Sirenians – have lipid filled zygomatic process (skull bone) connects to ear analogous to pan bone in odontocetes Poor directionality and lack of high frequency sound reception reason for high number of boat strikes

21. Pinniped Sounds In air vocalizations – classified by species, age, & sex Otariids more vocal than phocids Male calls – barks, roars, grunts Mother-pup calls – used specifically for recognizing & locating each other Underwater vocalizations – typically male “songs”

22. Pinniped Sounds Weddell seal N. Elephant seal California sea lion

23. Other Marine Mammal Sounds Walruses – males produce a series of knocking sounds Sirenians – chirp-squeaks; little geographic variation; key in keeping calves with mothers Sea otters – above water low-frequency sounds; similar to sea lions Polar bears – females – defensive growls; males - chuffs

24. Other Marine Mammal Sounds Walrus Manatee Sea Otter Polar Bear

25. Cetacean Sounds Echolocation – projecting short-duration sounds and listening for reflected echoes Signature whistles – narrow band frequency modulated (FM) sound with harmonic structure; specific to individuals Mysticete sounds – low-frequency sounds used for long distance communication Prey stunning sounds – loud blasts of sound called “bangs” to debilitate prey

26. Echolocation Used by about 20% of mammals (bats & odontocetes Evolved independently in 5 mammalian lineages (bats, shrews, hamsters, lemurs) Dolphins may use successive echolocation clicks followed by multiclick processing

27. Echolocation

28. Echolocation Bottlenose dolphin Risso’s dolphin Beluga whale Sperm whale

29. Signature Whistles Hypothesized that whistle broadcasts identity of the animal & other information (state of arousal, fear, food, etc) More social animals whistle more often Often different dialects representing regional distributions

30. Vocal Clans Killer whales & Sperm whales Pods share calls including calls specific to individuals Pods are loosely associated into clans; share clan specific calls as well – some but not all calls

31. Vocal Clans

32. Prey Stunning Sounds Blasts of sounds called “bangs” used to stun or debilitate prey First identified in sperm whales – jaw claps Energetics of sperm whale feeding ecology Evidence difficult to collect – 240-250 db of sound required for stunning

33. Empirical Evidence Empirical studies suggest that sounds not enough to debilitate – playback experiments; conducted with live fish but not live dolphins/porpoises

34. Mysticete Sounds Hypothesized to have some form of echolocation – never substantiated Different equipment – form/function of sounds production in odontocetes Most well known sound production from humpbacks- male songs

35. Mysticete Sounds Broad system clicks & pulses Low frequency whale tones with very long wavelengths Humpbacks sing long complex songs

36. Humpback Songs

37. Mysticete Sounds Blue whale Humpback whale Bowhead whale

38. Sound in the Ocean Sound pollution thought to be as detrimental to marine mammals as chemical, thermal, physical NATO & Navy Sonar war games ATOC – Acoustic Thermometry of Ocean Climate – 260 watt low frequency sounds

39. Sound in the Ocean Sound pollution thought to be as detrimental to marine mammals as chemical, thermal, physical NATO & Navy Sonar war games ATOC – Acoustic Thermometry of Ocean Climate – 260 watt low frequency sounds

40. Sound in the Ocean Sources of Human-Generated Ocean Noise Transportation: Aircraft, ships and boats, icebreakers, hovercrafts and vehicles on ice Dredging and Construction:Dredging, tunnel boring, other operations. Oil Drilling and Production:Drilling from islands and caissons, bottom-mounted platforms, and vessels; and offshore oil and gas production. Geophysical Surveys: Air-guns, sleeve exploders, and gas guns. Sonars: Fish finders, depth sounders, and military systems. Explosions Ocean Research: Seismology, acoustic propagation, acoustic tomography, acoustic thermometry

41. Sound in the Ocean Ocean Acoustic Tomography (Acoustic Thermometry) - technique used to measure temperatures across large distances in the ocean Sounds travel between transmitter and receiver of known distance (typically 100-5000km); time for sound to reach received depends upon temperature of water (and other variables)

42. Sound in the Ocean ATOC - Acoustic Thermometry of Ocean Climate Most infamous regarding marine mammals Public outrage and political reaction primarily caused by misinformation

43. Sound in the Ocean AMODE (Acoustic Mid-Ocean Dynamics Experiment) & SYNOP (Synoptic Ocean Prediction) – most recent versions

44. Workshop: Navy Sonar and Cetaceans: Why Does RIMPAC have us on High Alert?

45. What Is RIMPAC Rim of the Pacific Exercise – since 1971 World's largest international maritime exercise Hosted and administered by the US Navy, US Marine Corps, US Coast Guard & Hawaii National Guard Held biennially in June and July in Hawaii

46. Participants Always: United States, Canada, and Australia, Sometimes: United Kingdom, Japan, Republic of Korea, Chile, and Peru Observers: France, Singapore, Malaysia, the Philippines, Thailand, Colombia, Mexico, India, Ecuador, Indonesia, China and Russia

47. Purpose Enhance coordination armed forces in Pacific Key to military readiness; conflict "hot spots“ China & Taiwan North Korea & South Korea, US, Japan

48. Exercises Conduct ship-sinking & torpedo exercises Test new naval vessels and technology

49. Marine Mammals and Sound

50. Patterns of Concern Greece, May 1996 ‘atypical’ mass stranding of 12 Cuvier’s beaked whales associated with acoustic trials by vessels from NATO Bahamas, March 2000 16 whales (14 beaked, 2 minke) stranded over 2 days US Navy vessels were using active high intensity sonar Madeira, May 2000 3 Cuvier’s beaked whales over 4 days NATO naval exercises involving multiple ships