Terrestrial mammals get all the attention.  So we decided to show our aquatic mammals some love.  Sticking with cetaceans, today’s post is on the largest dolphin – orcas (Orcinus orca).

The word Orcinus is derived from Orcus – the mythological Roman god of the netherworld.  This is probably due to its fierce reputation as the ‘wolves of the sea’ as they are known to hunt other ocean mammals.

Orcas hunt in family groups, called pods, of up to 40 members using cooperative hunting strategies.  Different pods target different prey.  Resident pods tend to prefer fish while transient pods tend to target marine mammals.  Polar bears, birds, squids, even a moose has been recorded by analysing the stomach contents of orcas.

There are 3 recognised categories of vocalizations used by killer whales: clicks, whistles and discrete calls.  While clicks seem to be used solely for echolocation, whistles and discrete call are used when communicating within and among pods.  Each pod has their own dialect that sounds different from other pods.  This dialect tends to stay the same in a pod for up to six generations.

The IUCN Red list classifies orcas as a data deficit species – as further study is needed to determine whether there are more than one species of orca.  Send your sightings of orcas: http://mammalmap.blog.com/submit-your-sightings-online/

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