17. Humpback whale leisurely rolling around after surfacing to breathe. Wide ventral grooves run along its underside with females having a 15cm diameter hemispherical lobe in the genital region. This distinguishes them visually from males who generally have their penis hidden within a genital slit. Males reach sexual maturity when about 7 years old and the females at about 5 years.

Humpback Whale, Tonga