Elsevier

Animal Behaviour

Volume 68, Issue 6, December 2004, Pages 1435-1442
Animal Behaviour

Group courtship, mating behaviour and siphon sac function in the whitetip reef shark, Triaenodon obesus

https://doi.org/10.1016/j.anbehav.2004.02.018Get rights and content

We analysed video records of three mating events involving nine free-living whitetip reef sharks in Cocos Islands, Costa Rica to examine reproductive behaviour in this species. We describe several behaviours never before documented in this species, and four behaviours never before documented in any elasmobranch. Here, we also present the first hypothesis for the function of the male's paired reproductive organs, the siphon sacs, to be based on observations of mating sharks. We introduce terminology for three separate siphon sac structural components that are externally visible during courtship and mating in this species. Based on our analyses, as well as evidence from past mating studies, the siphon sacs in whitetip reef sharks appear to be used to propel sperm into the female's reproductive tract, not for flushing the female's reproductive tract of sperm from previous males. We discuss the implications of ‘group courtship’, ‘siphon isthmus constriction’, ‘reverse thrusting’, ‘postrelease gaping’ and ‘noncopulatory ejaculation’.

Section snippets

Methods

Digital video taken by S. Waterman at Cocos Island, Costa Rica in February 2001 recorded three mating events between whitetip reef sharks. There appeared to be hundreds of whitetip reef sharks present during 4 days of diving in the area, and the average water temperature was 24°C. Water depths at the site of mating activity varied from 12 to 18 m and reproductively active whitetips have been seen in this place and season for many years. From the video, it appeared that there were more males

Results

We determined actively courting individuals to be different in each of the three mating events based on their spot patterns and fin markings. Most surrounding males also appeared to be different for each event, although one male was observed circling during both events 1 and 2. Of the three mating events analysed, two (events 1 and 3) were between a single male and female per event. The other (event 2) initially involved four males and one female, with two of the males achieving pectoral fin

Discussion

Behaviours observed in this study closely paralleled those catalogued by Pratt & Carrier (2001) from observations of mating in nurse sharks, Ginglymostoma cirratum, and other elasmobranchs. These behaviours include: ‘arch’, ‘avoid’, ‘group behaviour’, ‘pectoral grasp’, ‘positioning and alignment’, ‘clasper flexion’, ‘insertion and copulation’ and ‘separating’. This is the first time several of these behaviours have been observed in whitetip reef sharks. Furthermore, the analysis of the video

Acknowledgments

We thank S. Waterman for allowing us to use his excellent underwater video footage for our analyses. We also thank J. Castro, E. Conklin, D. Strang and two anonymous referees for their helpful comments on this manuscript.

References (32)

  • J.M. Dodd

    Reproduction in cartilaginous fishes (Chondrichthyes)

  • P.W. Gilbert et al.

    The clasper–siphon sac mechanism in Squalus acanthias and Mustelus canis

    Comparative Biochemistry and Physiology

    (1972)
  • J.C. Carrier et al.

    Group reproductive behaviour in free-living nurse sharks, Ginglymostoma cirratum

    Copeia

    (1994)
  • J.I. Castro

    Biology of the blacktip shark, Carcharhinus limbatus, off the southeastern United States

    Bulletin of Marine Science

    (1996)
  • J.I. Castro et al.

    The reproductive biology of the chain dogfish, Scyliorhinus rotifer

    Copeia

    (1988)
  • D.D. Chapman et al.

    Mating behavior of southern stingrays, Dasyatis americana (Dasyatidae)

    Environmental Biology of Fishes

    (2003)
  • A.F. Dixson

    Observations on the evolution of genitalia and copulatory behaviour in primates

    Journal of Zoology

    (1987)
  • W.G. Eberhard

    Sexual Selection and Animal Genitalia

    (1985)
  • W.G. Eberhard

    Animal genitalia and female choice

    American Scientist

    (1990)
  • A.E. Economakis et al.

    Aggregation behavior of the grey reef shark, Carcharhinus amblyrhynchos, at Johnston Atoll, central Pacific Ocean

    Environmental Biology of Fishes

    (1998)
  • K.A. Feldheim et al.

    Multiple paternity of a lemon shark litter (Chondrichthyes: Carcharhinidae)

    Copeia

    (2001)
  • R.G. Gilmore

    Reproductive biology of lamnoid sharks

    Environmental Biology of Fishes

    (1993)
  • R.G. Gilmore et al.

    Reproduction and embryonic development of the sand tiger shark, Odontaspis taurus (Rafinesque)

    U.S. Fisheries Bulletin

    (1983)
  • I. Gordon

    Pre-copulatory behaviour of captive sand tiger sharks, Carcharias taurus

    Environmental Biology of Fishes

    (1993)
  • A.H. Harcourt et al.

    Testis weight, body weight, and breeding system in primates

    Nature

    (1981)
  • C.J. Harvey-Clark et al.

    Putative mating behaviour in basking sharks off the Nova Scotia Coast

    Copeia

    (1999)
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    1

    H. L. Pratt is at the Mote Marine Laboratory, 24244 Overseas Highway, Summerland Key, FL 33042, U.S.A.

    2

    J. C. Carrier is at the Department of Biology, Albion College, Albion, MI 49224, U.S.A.

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