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DISPLAYING POSTS TAGGED: antarctica (4)

The truth is in the tooth

Author
by Kate C
Publish date
30 October 2012
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Leopard seals have jagged, three-lobed postcanine teeth at the backs of their jaws that fit together closely, almost like pieces of a jigsaw. These teeth were long presumed to allow these seals to sieve krill from the water, but the exact mechanism remained a mystery until now.

Leopard seal with mouth open A leopard seal at Taronga Zoo showing its teeth. The leopard seal has large canine teeth at the front of its jaw, and sieve-like cheek teeth at the back.
Image: Erich Fitzgerald
Source: Museum Victoria
 

skull and tooth of leopard seal The skull and postcanine tooth of the leopard seal. This detail comes from a working drawing in pencil, watercolour and indian ink that Becker made in preparation for Prodromus of the Zoology of Victoria.
Image: Ludwig Becker
Source: Museum Victoria
 

David Hocking and Dr Alistair Evans of Monash University, and Dr Erich Fitzgerald of Museum Victoria, have shown for the first time exactly how leopard seals can eat large prey, like penguins and seal pups, as well as small prey like krill. By observing live leopard seals at Taronga Zoo, their ingenious study reports that leopard seals use suction to draw small prey items into their mouths, then expel seawater out through the 'sieves' of their peculiar cheek teeth.

In this video, these scientists report their findings, as published last week in the journal Polar Biology.

 

Links:

David P. Hocking, Alistair R. Evans & Erich M. G. Fitzgerald. 'Leopard seals (Hydrurga leptonyx) use suction and filter feeding when hunting small prey underwater' in Polar Biology, published online 29 October 2012.

Caught and Coloured: Leopard seal

Ice Ice Baby

Author
by Mel
Publish date
3 May 2012
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Mel helps manage MV's Marine Invertebrates collections. In her spare time she works with honorary associate Mark O’Loughlin and others to develop her specialist knowledge of holothuroids, or sea cucumbers.

Ice was what I saw from my porthole each morning as I’d wake yet again to the realisation... Woohoo! I’m in Antarctica!

What a wonderful realisation it was. For nearly two months this summer my home was the British ice-strengthened research vessel the RSS James Clark Ross, and I loved every minute of my freezing, rolling, ice-crunching scientific voyage. On board at the invitation of the British Antarctic Survey and with the support of Museum Victoria, I was part of the biological research team tasked with collecting marine benthinc invertebrates from the shelf and slopes of the Weddell Sea in Western Antarctica.

View from the top View from the top of the RSS James Clark Ross
Image: Mel Mackenzie
Source: Museum Victoria

My regular work in the museum's Marine Invertebrate Collections held me in good stead to assist the biological team with our daily work of collecting, sorting, identifying, preserving, and DNA-sampling specimens as we brought these bottom-dwelling 'beasties' up in nets and sleds from the ocean floor. Our aim was to assess the biodiversity and evolutionary history of the area, and my particular focus was on sea cucumbers (holothuroids) which I have studied for a number of years now under the mentorship of Museum Victoria honorary associate Mark O'Loughlin.

James Rudd (ship’s doctor) The biology team
Image: Mel Mackenzie
Source: British Antarctic Survey

Relatives of animals such as the sea star, many sea cucumbers actually look more like sausages with tentacles (which explains their name), and have developed a variety of different feeding and reproductive methods to adapt to environments worldwide. They are diverse in Antarctic waters with over 180 species (including many undescribed) recorded south of the Antarctic Convergence, and as such, they make a good group for evolutionary study. Often coming up squashed in trawls they can be tricky to identify, but the key lies in a variety of identifiers from tentacle shape and number, to tube-foot arrangement and the tiny little skeletal remnants known as 'ossicles' which can be viewed in dissolved tissue under a microscope.

Sea cucumbers and bivalves clinging to urchin spines. Sea cucumbers and bivalves clinging to urchin spines.
Image: Mel Mackenzie
Source: Museum Victoria

With my previous experience of Antarctic sea cucumbers limited to pickled museum specimens, I was very excited to finally see these animals in living colour! They were amazingly diverse, from the tiny Psolids which clung to sea-urchin spines, to my favourite football-shaped 'sea-pigs' which the ship crew were delighted to see. We even got some footage (from cameras lashed to one of our collecting sleds) of different species feeding and moving about on the sea floor.

Along with sea cucumbers we saw many other amazing critters, from nets crawling with sea spiders to beautiful glass sponges filled with brittle stars and deep-sea fish with 'lights' attached to their heads... and that was just from below the water! On top we saw breaching Minke whales, majestic Emperors and curious (and chatty) chin-strap penguins against the always gorgeous background of floating icebergs. Stopping in the sub-Antarctic British Base at Signey to help close up for winter, we even had the chance to see (while firmly holding our noses) the huge elephant seals which roll their way around the camp.

Emperor penguin (left), Elephant seals Emperor penguin (left), Elephant seals at the UK’s Signy base
Image: Mel Mackenzie
Source: Museum Victoria

Links:

Skeletons of sea cucumbers, MV Blog post, April 2011

Penguin Awareness Day

Author
by Karen Rowe
Publish date
20 January 2012
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Karen Rowe is a Research Associate at MV where she studies evolutionary ecology and behaviour in birds and mammals.

January 20th is an auspicious day for birding enthusiasts, marking Penguin Awareness Day. With 17 species currently recognised, members of the family Spheniscidae (pronounced sfen-IS-kuh-dee) are found only within the southern hemisphere. While most of us think of penguins as cold-adapted animals, surviving long treks over ice to breed and raise their young in the middle of winter, many species live further north, among the islands off of Antarctica, along the coasts of New Zealand and Australia, and one species is found on the Galapagos Islands (the aptly named Galapagos Penguin).

Royal Penguins Royal Penguins (Eudyptes schlegeli) – among Elephant Seals on Macquarie Island.
Image: Julie McInnes
Source: Julie McInnes
 

As a group, penguins possess an amazing array of adaptations, uniquely suited to their predominately marine existence. Unlike other birds, penguins have solid, rather than air-filled bones, to help them dive in the water. They have highly modified feathers that form a thick insulating layer that cover the body, rather than growing in the well-defined feather tract found in other birds. They also have unique eyes that allow them to see clearly both on land and in the sea. And while their short legs and feet make them seem awkward on land, many species actually travel tremendous distances over land and rocks to reach their breeding sites – some even traveling as far as three kilometres from water.

Magellanic Penguin Captive Magellanic Penguin (Spheniscus magellanicus) floating in the water. The coloured flipper band allows zoo keepers to distinguish between individuals.
Image: Erich Fitzgerald
Source: Museum Victoria
 

Extant species show a wide range of body sizes, from our own Little (or Fairy) Penguins, weighing 1.1 kg and standing 40 cm tall, to the largest species, the Emperor Penguin, at a whopping 30 kg and up to 115 cm tall.

Little Penguins Little Penguins (Eudyptyla minor) in captivity. These coloured leg bands are another way to tell individuals apart.
Image: Erich Fitzgerald
Source: Museum Victoria
 

But even the Emperor Penguin is dwarfed in size by some of the extinct fossil penguins, including a 15-million-year-old giant penguin (Anthropodyptes gilli) from Victoria that may have approached twice its size. Senior Curator of Vertebrate Palaeontology, Dr. Erich Fitzgerald studies fossil penguins here at Museum Victoria. "Victoria was home to a remarkable diversity of penguins over the last 20 million years," says Dr. Fitzgerald. "The tiny Little Penguin living in Australia today is an oddity on a geologic timescale. The fossil record tells us that most penguins that have lived in Australia were large to huge in size and that at any one time there were perhaps two or more species coexisting here." Currently, Dr. Fitzgerald and his student, Travis Park, are working on six-million-year-old fossil penguins found in Melbourne on the shores of Port Philip Bay that are thought to be the size of the living Gentoo and Emperor Penguins.

Penguin limb bones The upper wing bone (humerus) of living penguins compared with their fossil counterparts from Victoria. From left to right: the 18-million-year-old fossil Anthropodyptes gilli; the living emperor penguin Aptenodytes forsteri; the living fairy penguin Eudyptula minor; the living gentoo penguin Pygoscelis papua; and the 6-million-year-old fossil Pseudaptenodytes. Credit: Photograph by Erich Fitzgerald
Image: Erich Fitzgerald
Source: Museum Victoria
 

Emperor Penguin and chick Emperor Penguin and chick, Antarctica.
Image: Julie McInnes
Source: Julie McInnes
 

The unique ecology of penguins makes them particularly susceptible to a variety of human-induced threats. In particular, commercial fishing, often leading to death through by-catch or competition for prey items (which include fish, crustaceans, and cephalopods), directly impacts their survival. Penguins are also dependent on breeding grounds close to the shore and habitat loss is a major source of population declines. Smaller and fewer breeding grounds also promotes disease, as most species of penguins breed in large colonies.

Royal Penguin colony Royal Penguin colony. This species is endemic to Macquarie Island and this is the largest Royal Penguin colony with over 180,000 breeding pairs. The fluffy young penguin in the front on the right is in moult.
Image: Julie McInnes
Source: Julie McInnes
 

Although little research has been done looking at the impact of climate change on penguins, their specialised lifestyle suggests that climate change could have dramatic impacts on their distribution and abundance. "Penguins are an ancient group of birds, with a history stretching back some 65 million years to the extinction of the dinosaurs," says Dr. Fitzgerald. "In southern Australia they have persisted through the last 20 million years of major climatic changes, but it is unknown how they will respond to the current human-exacerbated wave of environmental upheaval. It would be a terrible shame to see this ancient and superbly successful group of birds become threatened with extinction within our lifetime."

Adelie Penguin, Bechervaise Island, Antarctica. Adelie Penguin, Bechervaise Island, Antarctica.
Image: Julie McInnes
Source: Julie McInnes
 

Links:

Emperor Penguins in the Wild: Amazing animals in a changing world

Penguins on Atlas of Living Australia

Happy Feet Two at IMAX Melbourne

Dear Antarctican

Author
by Leonie
Publish date
16 March 2011
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This post comes from Leonie Cash, a librarian at the Museum Victoria library.

The MV Library received one of 150 invitations sent for a worldwide gathering of book collectors, librarians, archivists, and historians known as The Antarctic Circle. This group is united by their interest in the art and history of Antarctic studies.

The meeting in New Hampshire is organised by Robert Stephenson, a retired Harvard professor and founder of The Antarctic Circle. Unfortunately we can't attend the meeting, but Robert visited us recently to inspect MV's copy of Aurora Australis. This book is one of 90 copies printed under harsh conditions in Antarctica in 1907-08 during Ernest Shackleton's Nimrod expedition.

Robert and Leonie Founder of The Antarctic Circle, Robert Stephenson, and MV librarian, Leonie Cash, with MV's copy of Aurora Australis.
Source: The Antarctic Circle
 

Robert has visited libraries and personal collectors around the world comparing copies of Aurora Australis and the individual features of each copy are painstakingly recorded on The Antarctic Circle website. Each Aurora Australis is unique; the book was bound with covers made from wooden packing-cases which contained the expedition's provisions. The MV copy is stencilled CHICKEN and is signed by Ernest Shackleton and George Marston. We also have the 1988 facsimile edition in the Rare Books Collection of the library.

Details of Aurora Australia Details of MV's copy of Aurora Australia. Left: signatures of Ernest Shackleton and George Marston. Right: the inside back cover reads 'CHICKEN' from the original packing crate.
Image: Jon Augier
Source: Museum Victoria
 

Pages from Aurora Australis Two pages of MV's copy of Aurora Australis.
Image: Jon Augier
Source: Museum Victoria
 

Links:

The Antarctic Circle

Details of MV's copy on The Antactic Circle

MV News: Library Week rare book viewing

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