Abstract
Toothed whales use vision, chemical sensing, and touch for short-range communication, but they produce sounds to communicate over ranges of hundreds to thousands of meters. Sperm whales and porpoises communicate and echolocate using click sounds, and many toothed whales may eavesdrop on clicks. Many toothed whale species have two sound sources, one specialized for echolocation and the other for communication. Killer whales can independently modulate low-frequency clicks and a higher-frequency component to make complex communication signals. Dolphins click from the right sound source and produce tonal whistles from the left sound source. Bottlenose dolphins develop an individually distinctive whistle, called a signature whistle, through copying elements of sounds in their natal environment. Dolphins in the laboratory imitate synthetic whistle-like sounds, demonstrating their capacity to learn to produce vocalizations, a skill that is rare among nonhuman mammals. Adult dolphins can imitate the signature whistles of partners for use as a vocal label. These individual-specific labels are suited to the fission-fusion societies of most dolphins, in which group composition may change every few minutes. Killer whales, by contrast, live in stable matrilineal groups. They produce stereotyped calls that change slowly over generations, and a process of dialect formation leads members of each group to share a group-specific call repertoire. The process of call change suggests that killer whales learn to modify their calls based upon listening to other whales, but evidence for vocal learning is weaker than for dolphins. Sperm whales are usually sighted in temporary groupings formed of several more stable social units that may join for several days at a time. Sperm whales communicate with rhythmic patterns of clicks called codas. Codas are believed to have a short enough range to suggest a primary function for communication within a group, perhaps identifying group and individual identity. Social units that share the same coda repertoire are defined as members of the same vocal clan. Social units of the same vocal clan may join one another but joining is rare among sympatric units that have different repertoires, suggesting a role for codas mediating affiliation between units. The same repertoire may be recorded over tens of thousands of km, with the vocal clan comprising tens of thousands of whales. If codas are learned, then vocal clans would represent stable cultural traditions on a grand scale, but evidence for vocal learning is weak in sperm whales. Toothed whales have complex communication systems, but more work is needed to fully understand the role of learning, and we need more detailed longitudinal study of social relationships to fully understand functions of social communication.
Keywords
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
Abramson JZ, Hernández-Lloreda MV, García L, Colmenares F, Aboitiz F, Call J (2018) Imitation of novel conspecific and human speech sounds in the killer whale (Orcinus orca). Proc R Soc B 285(1871):20172171
Alexander G, Shillito EE (1977) The importance of odour, appearance and voice in maternal recognition of the young in Merino sheep (Ovis aries). Appl Anim Behav Sci 3(2):127–135
Antunes R, Schulz T, Gero S, Whitehead H, Gordon J, Rendell L (2011) Individually distinctive acoustic features in sperm whale codas. Anim Behav 81(4):723–730
Aoki K, Sakai M, Miller PJ, Visser F, Sato K (2013) Body contact and synchronous diving in long-finned pilot whales. Behav Process 99:12–20
Au WW, Moore PW (1984) Receiving beam patterns and directivity indices of the Atlantic bottlenose dolphin Tursiops truncatus. J Acoust Soc Am 75(1):255–262
Au WW, Branstetter BK, Benoit-Bird KJ, Kastelein RA (2009) Acoustic basis for fish prey discrimination by echolocating dolphins and porpoises. J Acoust Soc Am 126(1):460–467
Au WW, Branstetter B, Moore PW, Finneran JJ (2012) The biosonar field around an Atlantic bottlenose dolphin (Tursiops truncatus). J Acoust Soc Am 131(1):569–576
Baird RW, Stacey PJ (1988) Variation in saddle patch pigmentation in populations of killer whales (Orcinus orca) from British Columbia, Alaska, and Washington State. Can J Zool 66(11):2582–2585
Barlow J, Taylor B (1997) Acoustic census of sperm whales in the eastern temperate North Pacific. J Acoust Soc Am 102:3213
Barrett-Lennard LG (2000) Population structure and mating patterns of killer whales (Orcinus orca) as revealed by DNA analysis. PhD Thesis UBC, Vancouver
Baxi KN, Dorries KM, Eisthen HL (2006) Is the vomeronasal system really specialized for detecting pheromones? Trends Neurosci 29(1):1–7
Best PB (1979) Social organization in sperm whales, Physeter macrocephalus. In: Winn HE, Olla BL (eds) Behavior of marine animals, vol 3. Plenum, New York, pp 227–290
Bigg MA, Olesiuk PF, Ellis GM, Ford JK, Balcomb KC (1990) Social organization and genealogy of resident killer whales (Orcinus orca) in the coastal waters of British Columbia and Washington State. Report of the International Whaling Commission 12:383–405
Bøttcher A, Gero S, Beedholm K, Whitehead H, Madsen PT (2018) Variability of the inter-pulse interval in sperm whale clicks with implications for size estimation and individual identification. J Acoust Soc Am 144(1):365–374
Byrne RW (1999) Imitation without intentionality. Using string parsing to copy the organization of behaviour. Anim Cogn 2(2):63–72
Caldwell MC, Caldwell DK (1965) Individualized whistle contours in bottlenose dolphins (Tursiops truncatus). Nature 207:434–435
Caldwell MC, Caldwell DK (1979) The whistle of the Atlantic bottlenosed dolphin (Tursiops truncatus)—ontogeny. In: Winn HE, Olla BL (eds) Behavior of marine animals: current perspectives in research, vol 3. Plenum, New York, pp 369–401
Christal J, Whitehead H, Lettevall E (1998) Sperm whale social units: variation and change. Can J Zool 76(8):1431–1440
Clausen KT, Wahlberg M, Beedholm K, Deruiter S, Madsen PT (2010) Click communication in harbour porpoises (Phocoena phocoena). Bioacoustics 20:1–28
Connor RC, Smolker RA, Richards AF (1992) Dolphin alliances and coalitions. In: Harcourt AH, de Waal FBM (eds) Coalitions and alliances in humans and other animals. Oxford University Press, Oxford, pp 415–443
Connor RC, Heithaus MR, Barre LM (2001) Complex social structure, alliance stability and mating access in a bottlenose dolphin ‘super-alliance’. Proc R Soc Lond B 268:263–267
Cranford TW, Amundin M, Norris KS (1996) Functional morphology and homology in the odontocete nasal complex: implications for sound generation. J Morphol 228(3):223–285
D’Amico AD, Gisiner R, Ketten DR, Hammock JA, Johnson C, Tyack P, Mead J (2009) Beaked whale strandings and naval exercises. Aquat Mamm 35:452–472
Da Cunha RGT, Byrne RW (2009) The use of vocal communication in keeping the spatial cohesion of groups: intentionality and specific functions. In: Garber PA, Estrada A, Bicca-Marques JC, Heymann EW, Strier KB (eds) South American primates. Springer, New York, pp 341–363
Deecke VB, Ford JK, Spong P (2000) Dialect change in resident killer whales: implications for vocal learning and cultural transmission. Anim Behav 60(5):629–638
Dudzinski KM (1998) Contact behavior and signal exchange in Atlantic spotted dolphins (Stenella frontalis). Aquat Mamm 24:129–142
Fahlman A, Loring SH, Levine G, Rocho-Levine J, Austin T, Brodsky M (2015) Lung mechanics and pulmonary function testing in cetaceans. J Exp Biol 215:2030–2038
Foote AD, Griffin RM, Howitt D, Larsson L, Miller PJ, Hoelzel AR (2006) Killer whales are capable of vocal learning. Biol Lett 2(4):509-12
Ford JKB (1987) A catalogue of underwater calls produced by killer whales (Orcinus orca) in British Columbia. Can Data Rep Fish Aquat Sci, No. 633
Ford JKB (1989) Acoustic behavior of resident killer whales (Orcinus orca) off Vancouver Island, British Columbia. Can J Zool 67:727–745
Ford JKB (1991) Vocal traditions among resident killer whales Orcinus orca in coastal waters of British Columbia. Can J Zool 69:1454–1483
Ford JKB, Fisher HD (1983) Group-specific dialects of killer whales (Orcinus orca) in British Columbia. In: Payne R (ed) Communication and behavior of whales. Westview, Boulder, CO, pp 129–161
Gero S, Whitehead H, Rendell L (2016) Individual, unit and vocal clan level identity cues in sperm whale codas. R Soc Open Sci 3(1):150372
Herman LM, Peacock MF, Yunker MP, Madsen CJ (1975) Bottle-nosed dolphin: double-slit pupil yields equivalent aerial and underwater diurnal acuity. Science 189(4203):650–652
Janik VM, Sayigh LS (2013) Communication in bottlenose dolphins: 50 years of signature whistle research. J Comp Physiol A 199(6):479–489
Janik VM, Slater PJB (1997) Vocal learning in mammals. Adv Study Behav 26:59–99
Janik VM, Slater PJB (1998) Context-specific use suggests that bottlenose dolphin signature whistles are cohesion calls. Anim Behav 56:829–838
Janik VM, Sayigh LS, Wells RS (2006) Signature whistle shape conveys identity information to bottlenose dolphins. Proc Natl Acad Sci 103(21):8293–8297
Jensen FH, Perez JM, Johnson M, Soto NA, Madsen PT (2011) Calling under pressure: short-finned pilot whales make social calls during deep foraging dives. Proc R Soc Lond B Biol Sci 23:20102604. https://doi.org/10.1098/rsbl.2011.0701
Jensen FH, Beedholm K, Wahlberg M, Bejder L, Madsen PT (2012) Estimated communication range and energetic cost of bottlenose dolphin whistles in a tropical habitat. J Acoust Soc Am 131:582–592
Johnson MP, Tyack PL (2003) A digital acoustic recording tag for measuring the response of wild marine mammals to sound. IEEE J Ocean Eng 28(1):3–12
Jones G, Siemers BM (2011) The communicative potential of bat echolocation pulses. J Comp Physiol A 197(5):447–457
Ketten DR (1997) Structure and function in whale ears. Bioacoustics 8(1–2):103–135
King SL (2015) You talkin’ to me? Interactive playback is a powerful yet underused tool in animal communication research. Biol Lett 11(7):20150403
King SL, Sayigh LS, Wells RS, Fellner W, Janik VM (2013) Vocal copying of individually distinctive signature whistles in bottlenose dolphins. Proc R Soc Lond B 280:20130053
King SL, Harley HE, Janik VM (2014) The role of signature whistle matching in bottlenose dolphins, Tursiops truncatus. Anim Behav 96:79–86
Kishida T, Kubota S, Shirayama Y, Fukami H (2007) The olfactory receptor gene repertoires in secondary-adapted marine vertebrates: evidence for reduction of the functional proportions in cetaceans. Biol Lett 3(4):428–430
Laland KN, Galef BG (2009) The question of animal culture. Harvard University Press, Cambridge, MA
Laland KN, Janik VM (2006) The animal cultures debate. Trends Ecol Evol 21(10):542–547
Lammers MO, Au WW (2003) Directionality in the whistles of Hawaiian spinner dolphins (Stenella longirostris): a signal feature to cue direction of movement? Mar Mamm Sci 19(2):249–264
Macfarlane NBW (2016) The choreography of belonging: toothed whale spatial cohesion and acoustic communication. PhD Dissertation, MIT/WHOI Joint PhD Program, Cambridge, MA
Madsen PT, Payne R, Kristiansen NU, Wahlberg M, Kerr I, Møhl B (2002a) Sperm whale sound production studied with ultrasound time/depth-recording tags. J Exp Biol 205:1899–1906
Madsen PT, Wahlberg M, Møhl B (2002b) Male sperm whale (Physeter macrocephalus) acoustics in a high-latitude habitat: implications for echolocation and communication. Behav Ecol Sociobiol 53:31–41
Madsen PT, Carder DA, Bedholm K, Ridgway SH (2005) Porpoise clicks from a sperm whale nose—convergent evolution of 130 kHz pulses in toothed whale sonars? Bioacoustics 15:195–206
Madsen PT, Jensen FH, Carder D, Ridgway S (2011) Dolphin whistles: a functional misnomer revealed by heliox breathing. Biol Lett 8(2):211–213
Madsen PT, Lammers M, Wisniewska D, Beedholm K (2013) Nasal sound production in echolocating delphinids (Tursiops truncatus and Pseudorca crassidens) is dynamic, but unilateral: clicking on the right side and whistling on the left side. J Exp Biol 216:4091–4102
Mass AM, AYa S (1989) Distribution of ganglion cells in the retina of an Amazon river dolphin, Inia geoffrensis. Aquat Mamm 16:49–56
Mesnick SL, Evans K, Taylor BL, Hyde J, Escorza-Trevino S, Dizon AE (2003) Sperm whale social structure: why it takes a village to raise a child. In: De Waal FBM, Tyack PL (eds) Animal social complexity: intelligence, culture, and individualized societies. Harvard University Press, Cambridge, pp 444–464
Miksis JL, Tyack PL, Buck JR (2002) Captive dolphins, Tursiops truncatus, develop signature whistles that match acoustic features of human-made sounds. J Acoust Soc Am 112:728–739
Miller PJ (2002) Mixed-directionality of killer whale stereotyped calls: a direction of movement cue? Behav Ecol Sociobiol 52(3):262–270
Miller PJ, Shapiro AD, Tyack PL, Solow AR (2004a) Call-type matching in vocal exchanges of free-ranging resident killer whales, Orcinus orca. Anim Behav 67(6):1099–1107
Miller PJO, Johnson MP, Tyack PL (2004b) Sperm whale behaviour indicates the use of rapid echolocation click buzzes ‘creaks’ in prey capture. Proc R Soc B 271:2239–2247
Miller PJO, Johnson MP, Madsen PT, Biassoni N, Quero ME, Tyack PL (2009) Using at-sea experiments to study the effects of airguns on the foraging behavior of sperm whales in the Gulf of Mexico. Deep-Sea Res 56:1168–1181
Møhl B (2001) Sound transmission in the nose of the sperm whale, Physeter catodon. A post mortem study. J Comp Physiol A 187:335–340
Møhl B, Wahlberg M, Madsen PT, Heerfordt A, Lund A (2003) The monopulsed nature of sperm whale clicks. J Acoust Soc Am 114(2):1143–1154
Montgelard C, Catzeflis FM, Douzery E (1997) Phylogenetic relationships of artiodactyls and cetaceans as deduced from the comparison of cytochrome b and 12s rRNA mitochondrial sequences. Mol Biol Evol 14(5):550–559
Morisaka T, Connor RC (2007) Predation by killer whales (Orcinus orca) and the evolution of whistle loss and narrow-band high frequency clicks in odontocetes. J Evol Biol 20(4):1439–1458
Nachtigall PE, Hall RW (1984) Taste reception in the bottlenosed dolphin. Acta Zool Fenn 172:147–148
New LF, Moretti DJ, Hooker SK, Costa DP, Simmons SE (2013) Using energetic models to investigate the survival and reproduction of beaked whales (family Ziphiidae). PLoS One 8(7):e68725
Norris KS (1991) Dolphin days: the life and times of the spinner dolphin. W. W. Norton & Company, New York
Olesiuk PF, Ellis GM, Ford JKB (2005) Life history and population dynamics of northern resident killer whales (Orcinus orca) in British Columbia. Canadian Science Advisory Secretariat Research Document 2005/045. ISSN 1499-3848
Oliveira C, Wahlberg M, Johnson M, Miller PJ, Madsen PT (2013) The function of male sperm whale slow clicks in a high latitude habitat: communication, echolocation, or prey debilitation? J Acoust Soc Am 133(5):3135–3144
Pihlström H (2008) Comparative anatomy and physiology of chemical senses in aquatic mammals. In: Thewissen JGM, Nummela S (eds) Sensory evolution on the threshold: adaptations in secondarily aquatic vertebrates. University of California Press, Berkeley, pp 95–109
Quick NJ, Janik VM (2012) Bottlenose dolphins exchange signature whistles when meeting at sea. Proc R Soc B 279(1738):2539–2545
Quintana-Rizzo E, Mann DA, Wells RS (2006) Estimated communication range of social sounds used by bottlenose dolphins (Tursiops truncatus). J Acoust Soc Am 120(3):1671–1683
Rendell LE, Whitehead H (2003) Vocal clans in sperm whales (Physeter macrocephalus). Proc R Soc Lond B Biol Sci 270(1512):225–231
Rendell L, Whitehead H (2005) Coda playbacks to sperm whales in Chilean waters. Mar Mamm Sci 21(2):307–316
Richards DG, Wolz JP, Herman LM (1984) Vocal mimicry of computer-generated sounds and vocal labeling of objects by a bottlenosed dolphin, Tursiops truncatus. J Comp Psychol 98:10–28
Sakai M, Hishii T, Takeda S, Kohshima S (2006) Flipper rubbing behaviors in wild bottlenose dolphins (Tursiops aduncus). Mar Mamm Sci 22(4):966–978
Sayigh LS, Tyack PL, Wells RS, Scott MD (1990) Signature whistles of free-ranging bottlenose dolphins, Tursiops truncatus: mother-offspring comparisons. Behav Ecol Sociobiol 26:247–260
Sayigh LS, Tyack PL, Wells RS, Solow AR, Scott MD, Irvine AB (1999) Individual recognition in wild bottlenose dolphins: a field test using playback experiments. Anim Behav 57:41–50
Sayigh LS, Esch HC, Wells RS, Janik VM (2007) Facts about signature whistles of bottlenose dolphins (Tursiops truncatus). Anim Behav 74:1631–1642
Schulz TM, Whitehead H, Gero S, Rendell L (2008) Overlapping and matching of codas in vocal interactions between sperm whales: insights into communication function. Anim Behav 76(6):1977–1988
Schulz TM, Whitehead H, Gero S, Rendell L (2011) Individual vocal production in a sperm whale (Physeter macrocephalus) social unit. Mar Mamm Sci 27(1):149–166
Shapiro AD, Tyack PL, Seneff S (2011) Comparing call-based versus subunit-based methods for categorizing Norwegian killer whale, Orcinus orca, vocalizations. Anim Behav 81(2):377–386
Similä T, Ugarte F (1993) Surface and underwater observations of cooperatively feeding killer whales in northern Norway. Can J Zool 71(8):1494–1499
Smolker R, Pepper JW (1999) Whistle convergence among allied male bottlenose dolphins (Delphinidae, Tursiops sp.). Ethology 105:595–617
Smolker R, Mann J, Smuts B (1993) Use of signature whistles during separations and reunions by wild bottlenose dolphin mothers and infants. Behav Ecol Sociobiol 33(6):393–402
Sørensen PM, Wisniewska DM, Jensen FH, Johnson M, Teilmann J, Madsen PT (2018) Click communication in wild harbour porpoises (Phocoena phocoena). Sci Rep 8(1):9702
Strager H (1995) Pod-specific call repertoires and compound calls of killer whales, Orcinus orca Linnaeus 1758, in the water of northern Norway. Can J Zool 73:1037–1047
Tamaki N, Morisaka T, Taki M (2006) Does body contact contribute towards repairing relationships? The association between flipper-rubbing and aggressive behavior in captive bottlenose dolphins. Behav Process 73(2):209–215
Tavolga MC, Essapian FS (1957) The behavior of bottle-nosed dolphin (Tursiops truncatus): mating, pregnancy, parturition and mother-infant behavior. Zoologica 42:11–31
Teloni V, Johnson MP, Miller PJ, Madsen PT (2008) Shallow food for deep divers: dynamic foraging behavior of male sperm whales in a high latitude habitat. J Exp Mar Biol Ecol 354:119–131
Tougaard J, Carstensen J, Teilmann J, Skov H, Rasmussen P (2009) Pile driving zone of responsiveness extends beyond 20 km for harbour porpoises (Phocoena phocoena, (L.)). J Acoust Soc Am 126:11–14
Tougaard J et al (2014) Cetacean noise criteria revisited in the light of proposed exposure limits for harbour porpoises. Mar Pollut Bull. https://doi.org/10.1016/j.marpolbul.2014.10.051
Tyack P (1986) Whistle repertoires of two bottlenosed dolphins, Tursiops truncatus: mimicry of signature whistles? Behav Ecol Sociobiol 18:251–257
Tyack PL (2000) Dolphins whistle a signature tune. Science 289(5483):1310–1311
Tyack PL (2009) Effects of human-generated sound on marine mammals. Phys Today 62:39–44
van Opzeeland I, Corkeron PJ, Leyssen T, Simila T, Van Parijs SM (2005) Vocal behaviour of Norwegian killer whales, Orcinus orca, during carousel and seiner foraging on spring-spawning herring. Aquat Mamm 31:110–119
Wartzok D, Altmann J, Au W, Ralls K, Starfield A, Tyack PL (2005) Marine mammal populations and ocean noise: determining when noise causes biologically significant effects. National Academy Press, Washington, DC
Watkins WA, Schevill WE (1977) Spatial distribution of Physeter catodon (sperm whales) underwater. Deep Sea Res 24:693–699
Watwood SL, Tyack PL, Wells RS (2004) Whistle sharing in paired male bottlenose dolphins, Tursiops truncatus. Behav Ecol Sociobiol 55:531–543
Watwood SL, Owen ECG, Tyack PL, Wells RS (2005) Signature whistle use by temporarily restrained and free-swimming bottlenose dolphins, Tursiops truncatus. Anim Behav 69:1373–1386
Watwood SL, Miller PJO, Johnson M, Madsen PT, Tyack PL (2006) Deep-diving foraging behavior of sperm whales (Physeter macrocephalus). J Anim Ecol 75:814–825
Weaver A (2003) Conflict and reconciliation in captive bottlenose dolphins, Tursiops truncatus. Mar Mamm Sci 19(4):836–846
Weilgart L, Whitehead H (1993) Coda communication by sperm whales (Physeter macrocephalus) off the Galapagos Islands. Can J Zool 71(4):744–752
Weilgart L, Whitehead H (1997) Group-specific dialects and geographical variation in coda repertoire in South Pacific sperm whales. Behav Ecol Sociobiol 40:277–285
Wells RS (1991) The role of long-term study in understanding the social structure of a bottlenose dolphin community. In: Pryor K, Norris KS (eds) Dolphin societies: discoveries and puzzles. University of California Press, Berkeley, pp 199–225
Wells RS (2003) Dolphin social complexity: lessons from long-term study and life-history. In: De Waal FBM, Tyack PL (eds) Animal social complexity: intelligence, culture, and individualized societies. Harvard University Press, Cambridge, pp 32–56
Whitehead H (1998) Cultural selection and genetic diversity in matrilineal whales. Science 282(5394):1708–1711
Whitehead H (2003) Sperm whales: social evolution in the ocean. University of Chicago Press, Chicago
Whitehead H, Rendell L (2004) Movements, habitat use and feeding success of cultural clans of South Pacific sperm whales. J Anim Ecol 73(1):190–196
Whitehead H, Weilgart L (1991) Patterns of visually observable behaviour and vocalizations in groups of female sperm whales. Behaviour 118:275–296
Whitehead H, Waters S, Lyrholm T (1991) Social organization in female sperm whales and their offspring: constant companions and casual acquaintances. Behav Ecol Sociobiol 29:385–389
Yurk H (2005) Vocal culture and social stability in resident killer whales (Orcinus orca). Dissertation, University of British Columbia, Vancouver
Yurk H, Barrett-Lennard L, Ford JK, Matkin CO (2002) Cultural transmission within maternal lineages: vocal clans in resident killer whales in southern Alaska. Anim Behav 63(6):1103–1119
Zimmer WMX, Johnson M, Madsen PT, Tyack PL (2005a) Echolocation clicks of Cuvier’s beaked whales (Ziphius cavirostris). J Acoust Soc Am 117:3919–3927
Zimmer WMX, Tyack PL, Johnson M, Madsen P (2005b) 3-Dimensional beam pattern of regular sperm whale clicks confirms bent-horn hypothesis. J Acoust Soc Am 117:1473–1485
Zimmer WMX, Madsen PT, Teloni V, Johnson MP, Tyack PL (2005c) Off-axis effects on the multi-pulse structure of sperm whale usual clicks with implications for the sound production. J Acoust Soc Am 118:3337–3345
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2019 Springer Nature Switzerland AG
About this chapter
Cite this chapter
Tyack, P. (2019). Communication by Sound and by Visual, Tactile, and Chemical Sensing. In: Würsig, B. (eds) Ethology and Behavioral Ecology of Odontocetes. Ethology and Behavioral Ecology of Marine Mammals. Springer, Cham. https://doi.org/10.1007/978-3-030-16663-2_2
Download citation
DOI: https://doi.org/10.1007/978-3-030-16663-2_2
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-030-16662-5
Online ISBN: 978-3-030-16663-2
eBook Packages: Biomedical and Life SciencesBiomedical and Life Sciences (R0)