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Facts about Minke Whales

Sonia Nair
The minke whale is small and sleek with a pointed, triangular snout and dark-colored body. This story compiles some interesting facts about this whale.
Like other baleen whales, the minke whale too uses the comb-like baleen plates in its mouth to filter out plankton, krill, and small fish from the water.
Minke whales are baleen whales that belong to the suborder Mysticeti. These whales comprise the genus Balaenoptera of the family Balaenopteridae. Being a baleen whale, the minke whale indulges in filter feeding using the baleen plates on its upper jaw. The members of the family Balaenopteridae are also called rorquals, due to the pleated skin folds below their mouth. Minke whales are the most abundantly found baleen whales..

Minke Whale Taxonomy

As of now, there are two recognized species of minke whales. They are:

1. Common (or northern) minke whale (Balaenoptera acutorostrata)
2. Antarctic (or southern) minke whale (Balaenoptera bonaerensis)
According to some taxonomists, there is a third species called the dwarf minke whale. However, they are still not recognized as a separate species. The northern minke whale has two subspecies: (i) Balaenoptera acutorostrata scammoni in the North Pacific; and (ii) Balaenoptera acutorostrata acutorostrata in the North Atlantic.

What Does a Minke Whale Look Like?

✦ Size: Minke whales are believed to be the second smallest among the baleen whales. Females can grow slightly bigger than the males and attain an average body length of around 25 feet.
In case of males, the length may range between 23 to 24 feet. However, the maximum length of a minke whale can be around 35 feet. While their average body weight ranges between four to five tons, some can grow up to ten tons.
The minke whale has a sleek, streamlined body that is dark gray to black in color. The ventral side of its body may have a lighter or whiter shade. The upper rostrum (snout) is narrow and triangular with a ridge that extends to the two blowholes that are located near the top of the head.
✦ Baleen Plates and Throat Grooves: Instead of teeth, this whale has two rows of yellowish-white baleen plates that grow on the upper jaw. Each side of the jaw has around 300 baleen plates that can be about 11 inches in length. The structure of the baleen plates resemble the teeth of a comb.
In Antarctic minke whales, the baleen plates can have a combination of white and gray colors. Even the number and size of baleen plates are said to be higher in the southern species. It is said that dwarf minke whales have white baleen plates with a thin black border. The throat grooves are actually pleated folds of skin.
These grooves are found below the mouth and extend to the pectoral flippers. The function of this structure is to expand the buccal cavity (mouth), so as to take in the maximum amount of water, along with the prey.

Throat grooves and flippers

✦ Flippers and Fins: The sickle-shaped (falcate) dorsal fin of a minke whale is located towards the posterior side of the body. These whales have small ridges near the tail. The broad flukes (two lobes of the tail) with a notched center have pointed tips.
The pectoral flippers in northern minke whales are long with a broad, white band. Antarctic minke whales do not have this band, but their flippers may have white edges.
In case of the dwarf minke whale, a white patch can be seen on the upper part of the flippers. This white patch may extend to the back. In general, the flippers of these whales have pointed tips.
The features of minke whales may vary slightly with the species, their geographical location, etc. Individuals of the same species and location may also display some variations.

Where are Minke Whales Found?

While common minke whales are found in most of the oceans in the Northern Hemisphere, the Antarctic ones are found in the Southern Hemisphere. The latter can be seen in the southern Atlantic Ocean, between 20°S to 65°S.
During summer, they can be found in regions where there are thick layers of ice. Antarctic minke whales are found in large numbers in areas, like Prydz Bay, the Weddell Sea, and the Ross Sea.
The common minke whales are found in almost all oceans, especially in the latitude range of 65°S to 80°N. Apart from the North Atlantic and North Pacific, these whales can also be seen in the Southern Hemisphere.

The range of dwarf minke whales may sometimes overlap with that of the Antarctic ones. They can be found in oceans near Australia and South Africa. Minke whales are highly migratory, especially the common minke whales. They can be seen in both coastal and offshore waters. Sometimes, these whales are seen in bays and estuaries too.

Diet and Feeding Habits

Both the baleen plates and throat grooves help the whale in filter feeding, which involves gulping large amounts of water. The skin folds (of the throat grooves) expand to accommodate maximum amount of water in a single move.
The water is then filtered through the baleen plates that function like a sieve to retain the prey inside the mouth. While Antarctic minke whales feed exclusively on krill, a common minke whale's diet consists of a wide array of fish, like sardines, squid, herring, copepods, etc. They may also feed on plankton.

Filter feeding in a baleen whale

Minke Whale Behavior

Minke whales are mostly solitary in nature, but small groups of two to three individuals are not uncommon. During migration, these whales may move around in large numbers. Minke whales are really fast swimmers who can move at a maximum speed of 24 miles per hour.
During feeding, these whales lower their speed to 6 miles per hour. As they dive, they arch their backs and display the dorsal fin, but the flukes may not be seen. Usually, they take short dives that last for around ten minutes, though they are capable of taking longer dives too.
They breathe through the blowholes located on the top of the head. They take in air at the surface, but the spouts are not that prominent, as they exhale far below the water surface. The spouts are more visible in the Antarctic species.
✦ Reproduction: Minke whales reach sexual maturity around the age of three to eight. Antarctic minke whales may take longer (seven to eight years), when compared to the common ones. Usually, mating takes place during winter, and the gestation period is around 11 months. A single calf is born with a body weight of 0.4 to 0.5 tons and a length of 8 to 12 feet.
✦ Vocalization: These whales are known for their unique vocalization. Some of their sounds are so unusual that they are named star wars, boing, etc. Other vocalizations include clicks, grunts, pulse trains, and thumps. The name 'star wars' was given, as the particular sound resembled that of a laser gun from 'Star Wars'. It is believed that this particular sound is used by these whales to attract females.
Minke whales are said to be the most abundant among the baleen whales. While the common minke whale comes under the 'Least Concern' list of the IUCN (International Union for Conservation of Nature), the Antarctic minke whale is in the 'Data Deficient' list.
As of now, the population of minke whales is considered stable, but certain regions have shown a decline in numbers due to whaling and fishing activities. Another possible threat is underwater sounds that may interfere with their communication