There aren't any good pictures of Sei Whales, so here is a drawing.
The Sei Whale, Balaenoptera borealis, can grow to be about 65 feet long, and 50 tons.
It can be found in all oceans, but prefers deep off-shore waters, and avoids polar and tropical waters as well as semi-enclosed bodies of water.
The Sei Whale feeds at the surface of the ocean. It swims on its side through swarms of zooplankton or small fish, to obtain about a ton of food each day.
It is also from the phylum Cordata, which means that it has each of the following at some point in its life:
a notochord
pharyngeal slits
a hollow dorsal nerve cord
an endostyle
post-anal tail
Mating occurs in temperate subtropical areas during the winter. The gestation period is estimated to be anywhere from Ten and a half months, to a year. The reason that the period is such a large range is because no one has been able to observe the entire pregnancy cycle yet.
