Dolphin Development

From Embryology


Dolphin anatomy


Some Recent Findings

  • Seasonality, estrous cycle characterization, estrus synchronization, semen cryopreservation, and artificial insemination in the Pacific white-sided dolphin (Lagenorhynchus obliquidens). [1] "Ovulations and conceptions occurred from August to October. Peak mean serum testosterone, cross-sectional testicular area , and sperm concentration occurred in July, August, and September respectively. Spermatozoa were only found in ejaculates from July to October. Estrous cycles were 31 d long and were comprised of a 10 d follicular and 21 d luteal phase. Ovulation occurred 31.2 h after the onset of the LH surge and 19.3 h after the LH peak."
  • True hermaphroditism: first evidence of an ovotestis in a cetacean species[2] "An immature unilateral hermaphrodite common dolphin (Delphinus delphis) was found stranded on the southwest coast of the UK. The external phenotype was that of a female, but internally there was one ovotestis, containing both ovarian follicles and testicular tubular elements, and a contralateral ovary. Ovarian portions of the ovotestis appeared normal and demonstrated follicular development, whereas the testicular tissue exhibited hypoplasia and degeneration."


Suborder Odontoceti, toothed whales

  • Family Delphinidae, oceanic dolphins
  • Family Platanistidae
  • Family Iniidae
  • Family Lipotidae
  • Family Pontoporiidae


  • Common bottlenose dolphin (Tursiops truncatus)
  • Indo-Pacific bottlenose dolphin (Tursiops aduncus)
  • Burrunan dolphin (Tursiops australis)

Development Overview

Limb Development

Hind-limb loss in embryos of the dolphin.[3]

Researchers have identified that Sonic hedgehog (Shh), that in limb development is the signaling activity of the zone of polarizing activity (ZPA), is absent from the dolphin hind-limb bud. An absence of Hand2, an upstream regulator of Shh, leads to the failure to establish a ZPA.[3] The hind-limb bud initiates, but then bud arrests and degenerates around the fifth gestational week.

Dolphin limb development 02.jpg

Links: Limb Development | Sonic hedgehog


  1. T R Robeck, K J Steinman, M Greenwell, K Ramirez, W Van Bonn, M Yoshioka, E Katsumata, L Dalton, S Osborn, J K O'Brien Seasonality, estrous cycle characterization, estrus synchronization, semen cryopreservation, and artificial insemination in the Pacific white-sided dolphin (Lagenorhynchus obliquidens). Reproduction: 2009, 138(2);391-405 PubMed 19494046 | Reproduction
  2. S Murphy, R Deaville, R J Monies, N Davison, P D Jepson True hermaphroditism: first evidence of an ovotestis in a cetacean species. J. Comp. Pathol.: 2009, 144(2-3);195-9 PubMed 20708743
  3. 3.0 3.1 J G M Thewissen, M J Cohn, L S Stevens, S Bajpai, J Heyning, W E Horton Developmental basis for hind-limb loss in dolphins and origin of the cetacean bodyplan. Proc. Natl. Acad. Sci. U.S.A.: 2006, 103(22);8414-8 PubMed 16717186 | PNAS


O T Oftedal Lactation in whales and dolphins: evidence of divergence between baleen- and toothed-species. J Mammary Gland Biol Neoplasia: 1997, 2(3);205-30 PubMed 10882306


Mark Sklansky, Michael Renner, Patricia Clough, Gregg Levine, Michelle Campbell, Rae Stone, Todd Schmitt, Ruey-Kang Chang, Jayne Shannon-Rodriguez Fetal echocardiographic evaluation of the bottlenose dolphin (Tursiops truncatus). J. Zoo Wildl. Med.: 2010, 41(1);35-43 PubMed 20722252

Eric W Montie, Gerald E Schneider, Darlene R Ketten, Lori Marino, Katie E Touhey, Mark E Hahn Neuroanatomy of the subadult and fetal brain of the Atlantic white-sided dolphin (Lagenorhynchus acutus) from in situ magnetic resonance images. Anat Rec (Hoboken): 2007, 290(12);1459-79 PubMed 17957751

Vera M F da Silva, Anthony M Carter, Carlos E Ambrosio, Ana F Carvalho, Marina Bonatelli, Marcelo C Lima, Maria Angelica Miglino Placentation in dolphins from the Amazon River Basin: the Boto, Inia geoffrensis, and the Tucuxi, Sotalia fluviatilis. Reprod. Biol. Endocrinol.: 2007, 5;26 PubMed 17597550

David Sedmera, Ivan Misek, Milan Klima, Robert P Thompson Heart development in the spotted dolphin (Stenella attenuata). Anat Rec A Discov Mol Cell Evol Biol: 2003, 273(2);687-99 PubMed 12845705

K N Gray, R H Conklin Multiple births and cardiac anomalies in the bottle-nosed dolphin. J. Wildl. Dis.: 1974, 10(2);155-7 PubMed 4856964


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Cite this page: Hill, M.A. 2017 Embryology Dolphin Development. Retrieved March 23, 2017, from

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© Dr Mark Hill 2017, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G