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).
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| 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.
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| 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
I never knew Orcas possessed strong family bonds and social structure. Thats so interesting that differences in learning, such as the different hunting techniques can lead to strong variation between families. You say potential speciation, has there been much research on whether speciation has occurred, even in smaller isolated populations?
ReplyDeleteHi Elsea,
DeleteIt is thought that cultural differences in the form of learned behaviours between ecologically divergent killer whale populations have resulted in such strong isolation, even when orca communities are in sympatry, that speciation could definitely be developing. Not sure how long that process would take though :)
Very cool! I find it absolutely astounding at how these animals show different cultures and also the variety of different hunting styles is absolutely incredible! I’ve heard stories that killer whales are one of the few mammals that “play” with their prey – and may not even eat it after killing it. Is this true? How do you think culture has evolved in this group of animals! Great post!
ReplyDeleteHi Tasmin!
DeleteI have heard about orcas that play with prey, in particular one incident on the beaches of Patagonia where a mature female beached herself and captured a sea lion pup, only to gently return it to the shore after. I am not sure why these incidents occur, but perhaps orcas are so intelligent and complex that they may feel sympathy? I think culture may have evolved in these animals due to their level of intelligence and ability to observe and learn. Based on findings regarding their ability to mimic behaviours from one another, it would be likely that a pod could learn to specialise in a particular successful hunting technique or other social behaviours and eventually pass it on to following generations. Combined with their difference in home ranges and variety of language dialects, all these factors are probably likely for the formation of individual cultures.
Thanks for your thought-provoking and fascinating insights into these diverse and strange hunting techniques across the animal kingdom! I’ve enjoyed the style and content of your posts and will keep my eyes open for new and emerging ideas in this field for sure!
ReplyDelete