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Photo courtesy of super devoika





Blue whales have the largest penises on Earth. An erect blue whale penis is 12 inches in diameter and ten feet in length. It is fibroelastic like those of the blue whale's artiodactyl relatives. The retracted penis curves in an S-shaped loop and stays inside the body. When erect, it peaks out of the genital slit. Blue whales also have a distal spiral valve as a spermatic tube. Cetaceans do not have scrotums like terrestrial mammalian males do. Mammalian scrotums lower ambient temperature to keep sperm viable, so cetaceans had to find a way to compensate. And they did. Blood in veins that go through fins and the fluke loses heat. When that blood is sent directly to the testes, the sperm are cooled below body temperature and remain viable. The females have a long vulva with two nipples on each side to nourish newborns. They go in heat any time of the year, but the most common is during the migration to warmer waters for mating season.

Whale Penis

Blue whale penis. Photo courtesy of rwhgould




Blue whales reach sexual maturity between the age of 5 and 10. They are dioecious and undergo sexual reproduction. Normally, they migrate near the equator to reproduce. Blue whales undergo a very elaborate mating ritual. The male and female spend time rolling around each other, then they take a deep dive into the ocean abyss as they continue to communicate with each other. Suddenly, they fly upwards and cross the surface, and as the do the male thrusts the penis into the vulva and ejaculates.


Sexual Reproduction


Blue whales reproduce via sexual meiosis. The male and female each produce haploid gametes. Male gametes are sperm, and the female gametes are eggs. A single sperm and egg fertilize to form a diploid zygote. They fertilize internally, meaning sperm is deposited inside the female.

Gametic meiosis

Photo courtesy of Wikipedia Commons.

Development and Birth


Since blue whales are placental mammals, the fetus develops inside of the mother in the uterus. The blue whale fetus grows quickly at 1 inch per day after 3 months of gestation, and by the seventh month it stretches to 12 feet in length. The calf is born tail first after a 12 month pregnancy, and it weighs 6,000 pounds. Birth occurs primarily in winter and in early spring in warm waters. When born the calf immediately swims to the surface for oxygen. The mother watches over the young calf for a year, feeding it up to 200 pounds of milk per day.

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