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DISPLAYING POSTS TAGGED: cetacea (2)

First fossil of Pygmy Right Whale

Author
by Kate C
Publish date
10 August 2012
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The Pygmy Right Whale (Caperea marginata) is the oddball of the whale world. The bizarre anatomy of this species has confounded researchers for years – even its common name demonstrates our historical lack of understanding. Its arched upper jaw and skim-feeding behaviour is similar to the right whales however DNA analysis shows that Pygmy Right Whales are more closely related to the rorquals (family Balaenopteridae) than the true right whales (family Balaenidae).

The puzzle of the evolutionary history of this species was not helped by the fact that it appeared completely absent from the fossil record. Palaeontologist and whale expert Erich Fitzgerald was therefore extremely pleased to identify a lone fossil specimen in the Museum Victoria as a partial periotic (the bone that surrounds the inner ear) of an ancient relative of the Pygmy Right Whale.

One theory about this group, explains Erich, is that "the bizarre features of the Pygmy Right Whale evolved rapidly within the last three to four million years. But this fossil suggests that they're much older than that." The specimen, which Erich describes as "looking like a coconut," is larger than the periotic of the living Pygmy Right Whale and dates to the late Miocene. This makes it six million years old, which will help calibrate the whale phylogenies (evolutionary trees) that are based on DNA sequences.

four views from different angles of whale earbones. Comparison of the incomplete fossil specimen (left) with a complete earbone of a juvenile Pygmy Right Whale.
Image: Erich Fitzgerald
Source: Museum Victoria / Journal of Vertebrate Paleontology

 
It is the peculiar skeleton of the Pygmy Right Whale, particularly of its ear bones, that allowed Erich to identify such an odd and incomplete fossil. "Baleen whales in general have strange skulls but in Pygmy Right Whales the ear bones are particularly strange because the back end, of the periotic, is enormous and bulbous. This fossil has no features that would ally it with any other family."

The strangeness of this whale doesn't end with its skull. First up, there is its size; at just 6.5 metres long, it's the smallest living baleen whale. Compare this with its colossal distant relatives, such as the 33 metre Blue Whale. But there's more, says Erich. "If we look beyond the head, there are some really strange things. In particular, the Pygmy Right Whale has ribs that are flattened and expanded. It almost looks like the ribs have formed a shield over the organs." This may relate to their unusual way of swimming which requires a stiffer trunk. "A young animal filmed underwater in South Africa shows that they flex their entire body not just the tail. It's thought that the ribs may be expanded to help keep the body rigid during this movement."

Until this footage, almost all knowledge of the species came from stranded individuals. Recent aerial photographs of a pod of Pygmy Right Whales off the coast near Portland showed some kind of social behaviour but exactly what it is – feeding, reproducing or something else – is still unknown.

Museum of New Zealand Te Papa Tongarewa made this video with a dissection of a stranded whale which clearly shows the unusual ribs.

 

Links:

Erich M. G. Fitzgerald. 2012. Possible neobalaenid from the Miocene of Australia implies a long evolutionary history for the pygmy right whale Caperea marginata (Cetacea, Mysticeti). Journal of Vertebrate Paleontology 32(4): 976-980. DOI:10.1080/02724634.2012.669803

The Tetrapod Zoology blog has a series of three terrific posts about Pygmy Right Whales:
Caperea is really weird
More on little Caperea
Caperea alive

A whale of a time

Author
by Colin
Publish date
3 November 2011
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(Warning: this blog contains graphic images and bad puns.)

On 19 October I heard exciting news leaking down the underground corridors of Melbourne Museum and into the Live Exhibits Lab. Word that a Humpback Whale had beached itself on the western end of the Ninety Mile Beach in eastern Victoria, set my plan in motion to become involved in its subsequent recovery. I bailed up (approached) the Preparations Department manager Peter Swinkels in one of the corridors and offered my assistance. Fortunately he said yes and that if I could handle a tight squeeze in the car, I was welcome to come along and help out.

So we left the Museum the following Monday and headed for McGaurens Beach, a small stretch of coast located between Yarram and Sale. The car ride down was a bit of a squeeze with Peter Swinkels, Steven Sparrey (Preparation), Brendon Taylor (Preparation), Michael Pennell (Image Management & Copyright) and I (Live Exhibits) all stuffed into the Hilux for the three hour trip down to McGaurens Beach. We arrived around lunchtime, and started to inspect the dead whale and the surrounding conditions (such as the tide) to plan our course of action.

Humpback whales (Megaptera novaeangliae) belong to the suborder Mysticeti, the group known as the baleen whales. Baleen is the keratin (the same material your fingernails) plates that the whales use to filter their food (krill, other zooplankton and small fish) with. Adult humpback whales can measure between 12-16 metres, and can weigh over 30 tonnes!

When we arrived at McGaurens Beach the whale sat just above the low tide mark. It would make it very hard to work on the whale when the tide came in, so we decided to move it higher up the beach and out of reach of the tide. This way we could work on it all day.

Humpback Whale on beach The Humpback Whale 6 days after it had died.
Image: Colin Silvey
Source: Museum Victoria
 

To avoid damage to the flippers we removed them before the excavator dragged the whale up past the high tide mark. Although the excavator weighed 25 tonnes, it still struggled to pull the whale 50m up the beach.

Cutting off whale flippers Cutting off the flippers to enable easy movement up the beach.
Image: Colin Silvey
Source: Museum Victoria
 

To cut off the flippers and through the flesh we used very large sharp knives and a special knife shaped like a hockey stick, called a flensing tool. Flensing tools were what whalers used to use to cut the blubber off whales before commercial whaling was banned in 1986 by the International Whaling Commission (IWC). Some legal whaling still continues today in indigenous communities as traditional hunting, and through exploiting legal loopholes under the guise of scientific research.

Peter Swinkels with a traditional flensing tool Manager of Preparation, Peter Swinkels, with a traditional flensing tool.
Image: Colin Silvey
Source: Museum Victoria
 

After dragging the body past the high tide mark we took measurements of different parts of the whale. These measurements will be added to a big database full of information that helps us understand these wonderful creatures of the sea.

Measuring a whale Measuring the width of the tail flukes.
Image: Colin Silvey
Source: Museum Victoria
 

After all the measurements had been recorded it was time to remove the skeleton. Firstly, we needed to find some small vestigial bones that are the remnants of the whale's hip and hind legs. Millions of years ago the ancestors of the modern whales we see today had front and rear limbs, and while the forelimbs slowly evolved into flippers, the hind limbs slowly disappeared and all that is left is a few tiny bones.

Vestigial hind limbs of Humback Whale Peter Swinkels holding the vestigial hind limbs.
Image: Colin Silvey
Source: Museum Victoria
 

After cutting away most of the flesh and blubber we removed the vertebrae (the backbone). Slowly and carefully, we removed the ribs, the skull, and the mandible (the jawbone). All the fleshy waste was returned to sea, where it would be eaten and broken down by scavenging animals and bacteria.

Whale remains on beach The pile of blubber we made after removing it from the carcass.
Image: Colin Silvey
Source: Museum Victoria
 

Once we had all the bones, we dug a big hole and put the bones into it. We bury the bones so that bacteria and other flesh eating organisms can clean the bones for us. In about six months, we will return to where the bones are buried and bring them back to the museum for a few touch ups and further measurement. Perhaps one day they will be put on display at Melbourne Museum for you to see.

Whale bones in sand All the bones about to be buried in order to let the flesh decompose before taking them to Melbourne Museum.
Image: Colin Silvey
Source: Museum Victoria
 

Links:

ABC Gippsland: radio interview with Erich Fitzgerald

ABC Gippsland: photos and story about whale recovery

Infosheet: Blue Whale

MV News: Rare whale retrieved (2008)

MV Blog: What's that smell?

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