Blue whale

Whales are an important part of the marine food chain and play a huge role in maintaining the health of our oceans.

While it may be considered an endangered species, the blue whale is truly international, occurring in all oceans except the Arctic, and enclosed seas of course. Before whaling there may have been as many as 250,000; today, it is one of the world's rarest species, with the population of blue whales numbering just 10,000-25,000. Most biologists consider it among the most endangered of the great whales. Only one population, in the northeast Pacific off California, is showing real signs of recovery and it contains around 3,000 animals.

Blue whales require enormous amounts of food, but they’re a boon to rather than a burden on the ocean ecosystem. Their iron-rich poo is a really important source of nutrients in the marine food chain, promoting Southern Ocean productivity, which boosts fishery yields. These nutrients, particularly iron and nitrogen, are vital for phytoplankton, at the base of the food chain. Because plankton help to remove carbon dioxide from the atmosphere, you could go as far as to say that blue whales are carbon neutral. However you calculate it, whales are fertiliing their feeding grounds and providing sufficient nutrients to sustain krill populations.

Although there is debate surrounding the taxonomy of blue whales, there are five distinct subspecies: Antarctic blue whales in the Southern Ocean (Balaenoptera musculus intermedia); North Atlantic and North Pacific blue whales (Balaenoptera musculus musculus); Pygmy blue whales, found in the Southern Indian Ocean (Balaenoptera musculus brevicauda); Northern Indian Ocean (Balaenoptera musculus indica) and South Pacific Ocean (Balaenoptera musculus unnamed species) whales.

Did you know?

Blue whales dive for 10-20 minutes, and usually feed at depths of less than 100 metres.