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Species AbstractThe Antarctic minke whale (Balaenoptera bonaerensis), is a large cetacean, in the family of Rorquals (Balaenoptera). The Minke is a baleen whale, meaning that instead of teeth, it has long plates which hang in a row (like the teeth of a comb) from its upper jaws. Baleen plates are strong and flexible; they are made of a protein similar to human fingernails. Baleen plates are broad at the base (gumline) and taper into a fringe which forms a curtain or mat inside the whale's mouth. Baleen whales strain huge volumes of ocean water through their baleen plates to capture food: tons of krill, other zooplankton, crustaceans and small fish.
Balaenoptera bonaerensis is among the smallest among the rorquals. Mature males average 8.36 m ineters (m) length and weigh 6.85 tons, but an adult reach a total length of 9.63 m and a body mass of 11.05 tons. Females are slightly longer with a mean total length of 7.57 m and a maximum measured length of 10.22 m. On average, B. bonaerensis is slightly longer than all forms of B. acutorostrata. Similar to Balaenoptera acutorostrata, Antarctic minke whales are dark grey on the back with a pale ventral side. The main recognition character that allows for the distinction of Antarctic minke whales from Balaenoptera acutorostrata is the absence of a white patch on the flippers in Antarctic minke whales. The rostrum is narrow and pointed. The dorsal fin is hook-shaped and located about two-thirds the length of the body from the anterior. Baleen plates are black on the left side and on the posterior two thirds of the right side, while the remaining baleen plates are white. The baleen plate filaments average about 3.0 mm in diameter. Antarctic minke whales have larger skulls than Balaenoptera acutorostrata.
Minke whales in Antarctic feeding areas can be solitary or form small groups. They are generally seen in groups of two to four individuals. Distribution of individuals within these groups is relatively random. There seems to be an enhanced amount of clustering in relatively enclosed areas (e.g., bays) as opposed to open water habitats. Antarctic minke whales sometimes uses the rostrum to break ice several centimeters in thickness to create breathing holes. The distance between two neighboring holes usually ranges from 200 m to 300 m. The species is noted to actively avoid ships that are in motion; furthermore, it uses “porpoising” behavior in doing so.