The minke whale (Balaenoptera acutorostrata) is the second smallest of the baleen whales, measuring about 32.8 feet (10 m) in length. A distinctive triangular head, narrow and pointed snout, and sickle-shaped dorsal fin make this whale easy to identify. Generally, minke whales are black, gray, or brown on their dorsal surface and a light color on their ventral surface. These active, agile whales have good maneuverability and speed, able to travel at 10.4 miles per hour (17 kph) for short periods of time.
As baleen whales, minkes are carnivores whose mouths are equipped with smooth baleen plates for filtering small organisms from gulps of water. Minkes can be found worldwide and are known to live in deep oceans, along coasts, and in coral reefs. Instead of seasonal migration, they only travel to follow their food. Sometimes minkes chase schools of small fish such as sardines and herring, swimming beneath and scooping them up in their open mouths. As in humpbacks, the throats of minkes are pleated so that they can expand their bite size.
Females enter their reproductive periods on 14-month cycles. Gestation lasts for 10 months, and calves are born in mid-winter. There is usually only one calf, but twins and triplets do occur. A newborn calf is only about 8.53 feet (2.6 m) long but grows quickly on its mother’s milk, which supports the baby whale for four or five months. Young whales reach sexual maturity at seven years of age and live to be about 50 years old.
Minke whales are most often solitary animals, although they are also seen in small groups. When food is plentiful, several hundred animals may congregate in the feeding grounds where they communicate with grunts, clicks, and breaching. The sounds they produce are very low-frequency waves that can travel long distances under water. Worldwide populations of minke whales are larger than most other groups of whales, consisting of about a million animals. Because the whales are small, they have escaped predation by humans and maintained almost-normal population sizes.