T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network


Whale (Sei whale) Balaenoptera borealis

Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Family: Balaenopteridae
Genus: Balaenoptera
Species: B. borealis
Binomial name: Balaenoptera borealis
Common name: Sei whale 

The Sei whale (Balaenoptera borealis) is a baleen whale, the third-largest rorqual after the blue whale and the fin whale. It inhabits most oceans and adjoining seas and prefers deep offshore waters. 
Around February and March sei whales migrate south to Antarctic feeding grounds, but do not venture near the pack ice, as blue or fin whales do. They return to warmer waters to calve, passing through the Pacific Ocean to the east of New Zealand between the mainland and the Chatham Islands

Balaenoptera borealis is a lean, sleek, dark bluish-grey with a lighter underside. Their average weight is >25 tonnes and a length of >19.5 metres. It has a tall, sickle-shaped dorsal fin that ranges in height from >90 cm and is placed about two-thirds of the way back from the tip of the rostrum. 
It has a relatively short series of 32–60 pleats or grooves along its ventral surface that extend halfway between the pectoral fins and umbilicus (belly button). The rostrum is pointed, and the pectoral fins are relatively short and are pointed at the tips. 
It has a single ridge extending from the tip of the rostrum to the paired blowholes that are a distinctive characteristic of baleen whales. The whale's skin is often marked by pits or wounds, which after healing become white scars. These are caused by "cookie-cutter" sharks (Isistius brasiliensis).

Sei whales are filter feeders that use two feeding methods. 
1: They skim the surface of the sea with their mouths half open. They then swallow what has collected on their baleen plates. 
2: Another method of feeding is to open their mouth wide taking in a huge quantity of food and water and then expel the water leaving behind krill, copepods, other zooplankton. Sei whales are estimated to live for more than 50 years.

Sei whales are a very fast whale, they have been recorded at 50 kilometres per hour in a sprint. In the early day, they were capable of outrunning whaler’s rowboats until the advent of motorised chasers. 
The sei whale is now internationally protected. In 2017 after the latest round of Japanese whale hunts carried out under a controversial research program conducted by Japan, after four months they ended with a total of 134 Sei whales killed.



A baby sei whale lies stranded on the beach at Motupipi, Golden Bay.


A graphic showing the size of an adult Sei whale compared with a human.

Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0/