At one month in the womb, dolphins develop tiny leg-like limb buds that vanish within two weeks, and the animals swim in amniotic fluid for the next 11 months of gestation. Scientists say that evolutionary trick is a sign that the highly intelligent mammals descended from dog-like land creatures.
At nine months, the dolphin has no more room in the mother's uterus, so the fetus curls inside the uterine wall. Hairs like tiny whiskers on the dolphin will fall out after birth as a result of water pressure, but the pores will remain open.
At birth, the dolphin can see and swim, and has the musculature to follow its mother to the top of the ocean to get its first breath. When dolphins breathe, they exchange 80 percent of the oxygen in their bodies. Humans, in contrast, swap out only 17 percent.
Like humans, dolphins use sex as a form of bonding within their social groups. They have long sessions of foreplay, but the actual sex act lasts only seconds. Female dolphins have only one calf at a time and wait four and a half years between pregnancies.
Photo by Pioneer Productions
