Why become speckled? Ontogeny and function of speckling in Shark Bay bottlenose dolphins ( Tursiops sp.) 1

Bottlenose dolphins in Shark Bay, Western Australia, develop speckled patterns on their ventral sides starting at around 10.2 years of age, with speckles increasing in number and density throughout their lifespan. This study, tracking 88 dolphins from birth to age 34, found that while the onset of speckling does not differ significantly by sex, it correlates with sexual maturity in females, particularly aligning with the age of first parturition. The research suggests that speckle patterns likely serve a communicative function rather than concealment, as predation risk and hunting success peak much earlier in life. This finding challenges traditional assumptions about color pattern functions in cetaceans and highlights the potential for ventral speckling to signal reproductive status or condition.

Krzyszczyk, E., & Mann, J. (2011). Why become speckled? Ontogeny and function of speckling in Shark Bay bottlenose dolphins ( Tursiops sp.) ¹. Marine Mammal Science, 28(2), 295–307. Portico. https://doi.org/10.1111/j.1748-7692.2011.00483.x