Review of crocodilian communication: A research gap in acoustic and chemical signals in Gharial (Gavialis gangeticus)

Paper Details

Review Paper 11/07/2023
Views (503) Download (72)

Review of crocodilian communication: A research gap in acoustic and chemical signals in Gharial (Gavialis gangeticus)

Jailabdeen Ajjim, G. Archunan
J. Bio. Env. Sci.23( 1), 52-61, July 2023.
Certificate: JBES 2023 [Generate Certificate]


Crocodilians are a diverse group of reptiles that have been extensively studied for their morphology, behaviour, and ecology. However, the communication and signalling mechanisms in crocodilian species, especially for the critically endangered gharial, remain poorly understood. Acoustic communication in crocodilians is relatively well-documented, but the production and reception of acoustic signals remain understudied. The application of new technological advancements, such as the acoustic camera used in frogs, could greatly advance acoustic research in various species of crocodilians. In contrast, chemical communication research is comparatively more limited for all species of crocodilians, and has been limited to sampling captive animals, primarily in zoos. Studying both acoustic and chemical signalling in gharials could significantly contribute to the understanding of their behavioural ecology and aid conservation aspects. Furthermore, it would considerably enlarge the representation of contemporary crocodilians since gharials in captivity are few and largely unstudied. This review summarizes current understanding of acoustic and chemical communication in crocodilians and highlights the need for future research.


Ache BW, Young JM. 2005. Olfaction: diverse species, conserved principles. Neuron 48(3), 417-430.

AjjiM J, Lang JW, Singh RK, Archunan G. 2018. Gharial communication: acoustic signalling via”pops”. PP.1-6, in Proceedings: 13th Western Pacific Acoustics Conference; New Delhi.

AjjiM J, Lang J W, Archunan G. 2023. Gharials communicate via acoustic “POP” signals. Cibtech Journal of Zoology, 12, PP. 107-114

Alberts AC. 1990. Chemical properties of femoral gland secretions in the desert iguana, Dipsosaurus dorsalis. Journal of Chemical Ecology, 16, 13-25.

Archunan G. 2009. Vertebrate pheromones and their biological importance. Journal of Experimental Zoology, India, 12(2), 227-239.

Beeck V C, Heilmann G, Kerscher M, Stoeger AS. 2022. Sound Visualization Demonstrates Velopharyngeal Coupling and Complex Spectral Variability in Asian Elephants. Animals, 12(16), 2119.

Bennett SC. 1992. Sexual dimorphism of Pteranodon and other pterosaurs, with comments on cranial crests. Journal of Vertebrate Paleontology, 12(4), 422-434.

Belzer B. 2002. A nine year study of eastern box turtle courtship with implications for reproductive success and conservation in a translocated population. Turtle and Tortoise Newsletter, 6(1), 17-26.

Bradbury JW, Vehrencamp SL. 1998. Principles of animal communication. Sinauer Associates, Sunderland.

Britton AR. 2001. Review and classification of call types of juvenile crocodilians and factors affecting distress calls. Crocodilian biology and evolution, 18, 364-77.

Bruinjé AC, Coelho F E, Maggi BS, Costa GC. 2020. Chemical signalling behaviour in intrasexual communication of lizards lacking femoral pores. Ethology, 126(7), 772-779.

Calsbeek R, ZamoraCamacho FJ, Symes L B. 2022. Individual contributions to group chorus dynamics influence access to mating opportunities in wood frogs. Ecology Letters, 25(6), 1401-1409.

Campbell HW. 1973. Observations on acoustic behavior of crocodilians. Zoologica, 58(1), 1-11.

Chabert T, Colin A, Aubin T, Shacks V, Bourquin SL, Elsey R M, Acosta JG, Mathevon N. 2015. Size does matter: crocodile mothers react more to the voice of smaller offspring. Scientific Reports, 5(1), 15547.

Cooper Jr W E, Vitt L J. 1984. Conspecific odor detection by the male broad‐headed skink, Eumeces laticeps: Effects of sex and site of odor source and of male reproductive condition. Journal of Experimental Zoology, 230(2), 199-209.

Cooper Jr WE. 1996. Chemosensory recognition of familiar and unfamiliar conspecifics by the scincid lizard Eumeces laticeps. Ethology, 102(3), 454-464.

Cooper WE, Steele LJ. 1997. Pheromonal discrimination of sex by male and female leopard geckos (Eublepharis macularius). Journal of Chemical Ecology, 23, 2967-2977.

Cooper Jr. WE, PèrezMellado V. 2002. Pheromonal discriminations of sex, reproductive condition, and species by the lacertid lizard Podarcis hispanica. Journal of Experimental Zoology, 292(6), 523-527.

Diegert CF, Williamson TE. 1998. A digital acoustic model of the lambeosaurine hadrosaur Parasaurolophus tubicen. Journal of Vertebrate Paleontology, 18(3), 38A.

Dinets V. 2010. Nocturnal behaviour of American Alligator (Alligator mississippiensis) in the wild during the mating season. Herpetological Bulletin, 111, 4-11.

Dinets V. 2011. Effects of Aquatic Habitat Continuity on Signal Composition in Crocodilians. Animal Behaviour 82(2): 191–201.

Dinets V. 2013a. Long-Distance Signaling in Crocodylia. Copeia 2013(3): 517–26.

Dinets V. 2013b. Dragon songs: love and adventure among crocodiles, alligators, and other dinosaur relations. Skyhorse+ ORM.

Doody JS, Dinets V, Burghardt GM. 2021. The Secret Social Lives of Reptiles. JohnHopkins University Press, Baltimore

Dunn Jr B S, Weldon P J, Howard R W, McDaniel C A. 1993. Lipids from the paracloacal glands of the Chinese alligator (Alligator sinensis). Lipids, 28(1), 75-78.

Ehrenfeld JG, Ehrenfeld DW. 1973. Externally secreting glands of freshwater and sea turtles. Copeia, 305-314.

Eisner T, Meinwald J. 1995. The chemistry of sexual selection. Proceedings of the National Academy of Sciences, 92(1), 50-55.

García-Rubio S, Attygalle AB, Weldon PJ, Meinwald J. 2002. Reptilian chemistry: volatile compounds from paracloacal glands of the American crocodile (Crocodylus acutus). Journal of chemical ecology, 28, 769-781.

Garrick LD, Lang JW. 1977. Social Signals and Behaviors of Adult Alligators and Crocodiles. American Zoologist, 17(1), 225–239.

Garrick LD, Lang JW, Herzog HA. 1978. Social signals of adult American alligators. Bulletin of the AMNH; v. 160, article 3.

Grigg G, Kirshner D. 2015. Biology and evolution of crocodylians. CSIRO, Clayton, Australia.

Herzog HA, Burghardt GM. 1977. Vocalization in juvenile crocodilians. Zeitschrift für Tierpsychologie, 44(3), 294-304.

Hone DW, Naish D. 2013. The ‘species recognition hypothesis’ does not explain the presence and evolution of exaggerated structures in non‐avialan dinosaurs. Journal of Zoology, 290(3), 172-180.

Huggins SE, Parsons LC, Pena RV. 1968. Further study of the spontaneous electrical activity of the brain of Caiman sclerops: olfactory lobes. Physiological Zoology, 41(3), 371-383.

Johnsen PB, Wellington JL. 1982. Detection of glandular secretions by yearling alligators. Copeia, 1982(3), 705-708.

Knell RJ, Naish D, Tomkins JL, Hone DW. 2013. Sexual selection in prehistoric animals: detection and implications. Trends in ecology & evolution, 28(1), 38-47.

Labra A, Niemeyer HM. 1999. Intraspecific chemical recognition in the lizard Liolaemus tenuis. Journal of Chemical Ecology, 25, 1799-1811.

Lang JW, Chowfin S, Ross JP. 2019. Gavialis gangeticus. The IUCN Red List of Threatened Species 2019: e. T8966A3148543.

Legler J, Vogt RC. 2013. The turtles of Mexico: land and freshwater forms. University of California Press.

López P, Martín J. 2001. Pheromonal recognition of females takes precedence over the chromatic cue in male Iberian wall lizards Podarcis hispanica. Ethology, 107(10), 901-912.

Martín J, López P. 2011. Pheromones and reproduction in reptiles. Hormones and reproduction of vertebrates, 141-167.

Mason R T, Gutzke WH. 1990. Sex recognition in the leopard gecko, Eublepharis macularius (Sauria: Gekkonidae) Possible mediation by skin-derived semiochemicals. Journal of Chemical Ecology, 16, 27-36.

Mason RT. 1992. Reptilian pheromones. Biology of the Reptilia, Chicago: University of Chicago Press. 18, PP. 114–228.

Müller-Schwarze D. 2006. Chemical Ecology of Vertebrates. Cambridge: Cambridge University Press.

Murray CM, Crother BI, Doody J S. 2020. The evolution of crocodilian nesting ecology and behavior. Ecology and evolution, 10(1), 131-149.

Neill WT. 1971. The last of the ruling reptiles-Alligators, Crocodiles and their Kin. Columbia University Press 9, 1-486.

Quay WB. 1986. Glands. In Biology of the Integument: 2 Vertebrates (pp. 188-193). Berlin, Heidelberg: Springer Berlin Heidelberg.

Reber SA, Nishimura T, Janisch J, Robertson M, Fitch WT. 2015. A Chinese alligator in heliox: Formant frequencies in a crocodilian. Journal of Experimental Biology, 218(15), 2442–2447.

Reber SA, Janisch J, Torregrosa K, Darlington J, Vliet KA, Fitch W T. 2017. Formants provide honest acoustic cues to body size in American alligators. Scientific Reports, 7(1816), 1–11.

Reber SA. 2020. Crocodilians Are Promising Intermediate Model Organisms for Comparative Perception Research. Comparative Cognition and Behavior Reviews, 15.

Reese AM. 1915. The alligator and its allies. GP Putnam’s Sons.

Reese A M. 1921. The structure and development of the integumental glands of the Crocodilia. Journal of Morphology, 35(3), 581-611.

Roberto IJ, Botero-Arias R. 2013. The distress call of Caiman Crocodilus crocodilus (Crocodylia: Alligatoridae) in western Amazonia, Brazil. Zootaxa, 3647(4), 593-596.

Rose FL, Drotman R, Weaver WG. 1969. Electrophoresis of chin gland extracts of Gopherus (Tortoises). Comparative Biochemistry and Physiology, 29(2), 847-851.

Shafagati A, Weldon PJ, Wheeler JW. 1989. Lipids in the paracloacal gland secretions of dwarf (Paleosuchus palpebrosus) and smooth-fronted (P. trigonatus) caimans. Biochemical systematics and ecology, 17(5), 431-435.

Singh LAK, Rao RJ. 1990: Territorial behaviour of male Gharial Gavialis gangeticus in the National Chambal Sanctuary, India. Journal of the Bombay Natural History Society. 87(1):149-151.

Solomon SE. 1984. The characterisation and distribution of cells lining the axillary gland of the adult green turtle (Chelonia mydas L.). Journal of Anatomy, 138(Pt 2), 267.

Staniewicz AM. 2020. Acoustic communication of rare and threatened crocodilians and its use for population monitoring (Doctoral dissertation) School of biological science, University of Bristol.

Stevenson C. 2019. Crocodiles of the world: A complete guide to Alligators, Caimans, Crocodiles and Gharials. New Holland Publishers.

Urra H, Marín JF, Páez-Silva M, Taki M, Coulibaly S, Gordillo L, García-Ñustes M A. 2019. Localized Faraday patterns under heterogeneous parametric excitation. Physical Review E, 99(3), 033115.

Vergne A L, Avril A, Martin S, Mathevon N. 2007. Parent-offspring communication in the Nile crocodile Crocodylus niloticus: Do newborns’ calls show an individual signature? Naturwissenschaften 94, 49–54.

Vergne AL, Pritz MB, Mathevon N. 2009. Acoustic communication in crocodilians: from behaviour to brain. Biological Reviews, 84(3), 391-411.

Vergne AL, Aubin T, Taylor P, Mathevon N. 2011. Acoustic signals of baby black caimans. Zoology, 114(6), 313-320.

Vliet KA. 1989. Social Displays of the American Alligator. American Zoologist, 29, 1019-1031.

Weldon PJ, Shafagati A, Wheeler JW. 1987. Lipids in the gular gland secretion of the American alligator (Alligator mississippiensis). Zeitschrift für Naturforschung C, 42(11-12), 1345-1346.

Weldon PJ, Sampson H W. 1988. The gular glands of Alligator mississippiensis: Histology and preliminary analysis of lipoidal secretions. Copeia, 80-86.

Weldon PJ, Shafagati A, Wheeler J W. 1988. Lipids from the paracloacal glands of the American alligator (Alligator mississippiensis). Lipids, 23(7), 727-729.

Weldon PJ, Scott TP, Tanner M J. 1990. Analysis of gular and paracloacal gland secretions of the american alligator (Alligator mississippiensis) by thin-layer chromatography Gland, sex, and individual differences in lipid components. Journal of Chemical Ecology, 16, 3-12.

Weldon PJ, Tanner MJ. 1991. Gular and paracloacal gland secretions of crocodilians: A comparative analysis by thin-layer chromatography. Biochemical Systematics And Ecology, 19(2), 133-141.

Weldon PJ, Ferguson MW. 1993. Chemoreception in crocodilians: anatomy, natural history, and empirical results. Brain, Behavior and Evolution, 41(3-5), 239-245.

Weldon PJ, Wheeler JW. 2001. The chemistry of crocodilian skin glands. Crocodilian Biology and Evolution. GC Grigg, F. Seebacher, and CE Franklin (eds.). Surrey Beatty and Sons, Sydney, 286-296.

Weldon PJ, Flachsbarth B, Schulz S. 2008. Natural products from the integument of nonavian reptiles. Natural product reports, 25(4), 738-756.

Wheeler JW, Ibrahim SA, Weldon PJ. 1999. 2, 3-Dihydrofarnesyl and citronellyl esters in the paracloacal gland secretions of the brown caiman (Caiman crocodilus fuscus) from Costa Rica. Biochemical systematics and ecology, 27(1), 27-32.

Whitaker R, Basu D. 1982. The gharial Gavialis gangeticus): A review. Journal of the Bombay Natural History Society. Bombay, 79(3), 531-548.

Wiman C. 1931. Parasaurolophus tubicen n. sp. aus der Kreide in New Mexico. Nova Acta Regia Societas Scientarum Upsaliensis series 4,7,1-11.

Winokur RM, Legler JM. 1975. Chelonian mental glands. Journal of Morphology, 147(3), 275-291.

Wyatt, TD. 2014. Pheromones and Animal Behaviour. Cambridge: Cambridge University Press.

Young BA. 2003. Snake bioacoustics: toward a richer understanding of the behavioral ecology of snakes. The Quarterly Review o