Similarly
to human populations, genes are partly influenced by culture, and in recent
years the effect of ‘cultures’ has become evident in global killer whale
communities. Ecologically specialised groups of orcas are known as 'ecotypes', and are found worldwide. Different ecotypes of orcas reside in different areas, hunt differently, and even have different language equivalents (Reisch et. al, 2012).
Image: An orca breaches itself to reach a sea lion pup playing in the shallows. Photographer Frank Wirth (Accessed 25 May, 2014) |
There are a variety of orca ecotypes, each specialising in certain types of prey. In studies conducted in the North Pacific over 40 years, no Resident Killer Whale (fish specialists) had ever been recorded taking mammalian prey, and no Transient Killer whale (dolphin, porpoise and seal specialists) had ever been recorded taking fish prey (Herman et. al, 2005). A variety of techniques for hunting are used, and vary from group to group. These can include intentional stranding or beaching, bubble netting, wave washing off ice floes, tail smacking, endurance based exhaustion tactics and drownings.
Image: A group of orcas approach a seal resting on an ice floe. Photographer Göran Ingman (Accessed 25 May, 2014) |
Due to complex social bonds within families, it is thought that young members of the pod are educated through both observation and direct lessons, with a recent study conducted in 2013 showing that orcas can perform action imitation behaviours, where they observe a behaviour from another individual, and copy it (Abramson et. al, 2013).
Such significant differences have lead to a potential divergent speciation of the orcas, with ecotypes of different regions showing a variety of changes in overall size, body coloration and markings (Reisch et. al, 2012).
Image: Sourced from nmfs.noaa.gov (Accessed 25 May, 2014)
As there are so many different hunting techniques in this species, I have linked only one video.
PLEASE NOTE: For all the pinniped lovers out there, there is no happy ending.
Video with thanks to Discovery on Youtube:
References:
Abramson, J.Z., Hern ández-Lloreda, V., Call, J., Colmenares, F. (2013) Experimental evidence for action imitation in killer whales (Orcinus orca). Animal Cognition. 16(1): 11-22
Ford, J.K.B.
(2009) ‘Killer Whale – Orcinus orca’ in Perrin, W.F, Würsig, B.G. and
Thewissen, J.G.M’s Encyclopedia of Marine
Mammals, Academic Press, London. pp. 650 – 657
Herman, D.
P., Burrows, D. G., Wade, P. R., Durban, J. W., Matkin, C.O., LeDuc, R. G.,
Barrett-Lennard, L.G., Krahn, M. M. (2005) ‘Feeding ecology of eastern North
Pacific killer whales Orcinus orca
from fatty acid, stable isotope and organochlorine analyses of blubber
biopsies’ Marine Ecology Progress Series.
302: 275-291. http://www.int-res.com.elibrary.jcu.edu.au/abstracts/meps/v302/p275-291/
Reisch, R.,
Barrett-Lennard, L. G., Ellis, G. M., Ford, J.K.B, Deecke, V. B. (2012) ‘Cultural traditions and the
evolution of reproductive isolation: ecological speciation in killer whales?’ Biological Journal of the Linnean Society,
106: 1–17