Encountering Orca: The elusive Type Ds

by Jamie Watts (guest blogger)

02 November 2012 - On the way back from South Georgia towards the Beagle Channel, just coming onto the shelf near Isla de las Estados, a very nice surprise. Delphine announces 'orcas' before breakfast. Up onto the bridge, and there they were - a little way off, a group of three, then further ahead and further over another small group. All heading northwest, all travelling, but in no particular hurry. 

Straight away they looked different. Very pointed, slightly swept back dorsal fins, lots of black, moderately sized for orcas. Then the flash of white above the eye – tiny. I doubt myself at first but after a couple more breaths from the other orcas it’s very clear. Type Ds.  Jet black backs, gorgeously pointed and swept fins, the rounded, pilot whale-like snout and tiny eyepatch – doesn’t look like any other orca.

  

Photo © Andrew Bishop

We always knew there was only one species of orca, found worldwide. Even after a couple of decades of intensive study particularly of the Vancouver Island and Alaska orcas, the huge differences between populations were just thought to be clan variations. In the meantime, soviet researchers in the Antarctic – where the majority of the world’s orcas are found – described two grey-backed forms as new species. It was the cold war, Russian research was either ignored or unknown in the west, and the type specimens of the new species were lost in a museum flood.

But in the last few years, the rather different Antarctic types have become rather well-known.  Most are smaller than the ‘regular’ orcas, and grey and cream rather than black and white, with large or slanted eye-patches. Their coloration and their proportions are rather different.

Photo © Andrew Bishop

Then we started getting genetic work done on orca populations - and there are rather large differences between populations. Even the Vancouver Island orcas are probably two entirely different species. Turns out we have in the Antarctic at least four different forms: Type 'A' big 'normal' orcas (which may further prove to be several groups), type 'B' - grey and cream with huge eye patches (there are probably two very different sub-types here, one large and one small), type 'C' - small, grey and cream, and with a slanted eye patch. And then there is the enigmatic type 'D'. 

Photo © Andrew Bishop

The Ds were only described in 2010. We have no genetic material, almost nothing on their behaviour. Researchers looking through photographic records found pictures of some very odd-looking orcas. Seven records, all around the edges of the Antarctic. Unlike every other orca, their snout is rounded like a pseudorca or a pilot whale. The fins are gorgeously sleek, sharply pointed and swept-back. And the eyepatch – tiny, a fraction of the size seen in other orcas.  They are almost intermediate between orcas and their closest relatives. They’ve been photographed seven times. Until this morning.

After breakfast, twenty miles away, a larger male and a couple more – again type D. I’d love to stop and somehow try and get some sloughed skin – something.  But we’re running tight on time. Ushuaia beckons.

You can see more of Jamie's work at www.jamiewatts.co.uk. 

Photo © Andrew Bishop