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DISPLAYING POSTS TAGGED: marine biology (33)

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

Fishes of Australia website

Author
by Di Bray
Publish date
8 August 2012
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Di is Senior Collections Manager in our Sciences Department and is absolutely passionate about all things sciency. She loves telling people about the amazing and unique fishes found in our waters.

After a prolonged gestation, we recently launched the beautiful Fishes of Australia website in Adelaide at the Annual Conference of the Australian Society for Fish Biology

Fishes of Australia website banner showing title and fish Fishes of Australia website banner.
Source: Museum Victoria
 

The website, funded by the Australian Biological Resources Study, is hosted by Museum Victoria on behalf of OzFishNet, a group of fish experts who work at, or are associated with, museums in Australia and the CSIRO. Senior curator Martin Gomon and I worked with the museum's in-house design and development team to build the site, which will appeal to everyone with an interest in Australian fishes, whether they be divers, anglers, aquarists, students, teachers, or researchers. 

Leafy Seadragon fish Leafy Seadragon, Phycodurus eques
Image: Graham Short
Source: Fishes of Australia
 

Australia's amazingly rich and diverse fish fauna comprises about 5000 species. With so many fishes, the website is a work in progress, but photographs of over 800 species are already in the website's gallery. Eventually, we'll include detailed images and information on all Australian fishes – including tiny desert gobies from hot artesian springs in central Australia, weird and wonderful deep-sea critters found offshore, and all species on the Great Barrier Reef.

Green Moray Eel Green Moray Eel
Image: Steve Dreezer
Source: Steve Dreezer
 

We're also including fishes found in our territorial waters – those from our Antarctic and Subantarctic waters, plus the fishes of Ashmore, Cartier, Lord Howe, Norfolk, Christmas and Cocos Keeling islands.

Alison's Blue Devil fish Alison's Blue Devil, Paraplesiops alisonae
Image: Rudie Kuiter
Source: Aquatic Photographics
 

We've included a couple of user-friendly interactive keys – one to fish families, and the other to freshwater fishes (including the nasty introduced ones). Try them out on that weird fish you caught last summer, or put a name on your favourite aquarium species. We thank the many fantastic photographers who have allowed us to use their gorgeous images that illustrate the site.

Kiwi Hatchetfish Kiwi Hatchetfish, Polyipnus kiwiensis
Image: Robin McPhee & Mark McGrouther
Source: NORFANZ Founding parties
 

Threadfin Dragonfish Threadfin Dragonfish
Image: Julian Finn
Source: Museum Victoria
 

And finally, please 'Like' us on Facebook and tell us what you think.

Links:

www.fishesofaustralia.net.au

Orange army on the sea floor

Author
by Kate C
Publish date
23 May 2012
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Every year, thousands of Giant Spider Crabs (Leptomithrax gaimardii) congregate in Port Phillip Bay ahead of their annual winter moult.

When solitary, these crabs are often hard to spot; algae, sponges and sea squirts set up shop on their shells and provide excellent camouflage. However when the crabs aggregate and march, this hungry army is easy to spot. They scavenge whatever food they can find, including the wildlife on the shells of one another. The spectacle of hundreds of large orange crabs against the bare, sandy sea floor is an amazing sight.


It’s still a bit of a mystery what the aggregations are all about but senior curator Dr Julian Finn has some ideas from several years of observation.

Like many crustaceans, Giant Spider Crabs are protected by their hard body shell, rather like a suit of armour. The trouble is that a hard shell doesn’t allow room for growth. Crabs must shed their old skin to get bigger; they can expand their size in the brief window before the new skin hardens. The process of moulting takes up to an hour and all the crabs in an aggregation moult almost simultaneously.

Spider crab emerging Spider crab emerging from its old shell. The new shell is a vivid orange colour.
Image: Julian Finn
Source: Museum Victoria
 

Newly-moulted Giant Spider Crab Newly-moulted Giant Spider Crab in its fresh orange shell.
Image: Julian Finn
Source: Museum Victoria
 

A soft, freshly-moulted crab is irresistible to predators such as rays, seals and birds. By aggregating in the thousands an individual crab reduces its chance of being eaten, much the same way as mammals in herds find protection in numbers. Movement into shallow waters may help the crabs, usually dispersed throughout Port Phillip Bay, aggregate in a single mass and gain refuge from the strong tidal currents that scour the deep channels.

An earlier explanation that the annual aggregations were related to mating has thus far proved unlikely, as following the moulting of tens of thousands of crabs, only the odd couple has been observed to mate. We still don’t know however what happens when they disperse back into deep water. Julian believes this sudden influx of tender crab meat is an important part of the Port Phillip Bay food chain.

Spider crab moults Hundreds of cast-off spider crab moults on the sandy seabed.
Image: Julian Finn
Source: Museum Victoria
 

If you'd like to see some Giant Spider Crabs without the need for SCUBA gear, have a look at the entrance of the Marine Life exhibition at Melbourne Museum.

Port Phillip Taxonomic Toolkit

Author
by Blair
Publish date
15 March 2012
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Hey check out www.portphillipmarinelife.net.au – the new Port Phillip Taxonomic Toolkit website we launched this week! It's a joint initiative between the Department of Sustainability and Environment, and us at the museum.

Juvenile Scalyfin, jellyfish and biscuit stars in Port Phillip Bay. Left to right: Juvenile Scalyfin, jellyfish and biscuit stars in Port Phillip Bay.
Image: Julian Finn | Mark Norman
Source: Museum Victoria
 

There is a spectacular gallery of over 2,000 photographs that make it the site to surf if you don't want to get wet this dive season. And if you do get wet, then it's the one place to learn about the cool stuff you've seen underwater.

Have a click around and find your favourite pretty fin or an awesome octopus!

albatross, isopod and Moray Eel from Port Phillip Bay. Left to right: albatross, isopod and moray eel from Port Phillip Bay.
Image: Julian Finn
Source: Museum Victoria
 

The site has 1,001 species from Port Phillip Bay with more to come in 2012. There are frowning faces of stargazers to picture-perfect blue devils, fish that walk instead of swim, cannibalistic sea cucumbers, and seahorses that eat lunch like sucking a hotdog out of a roll. They're all part of our truly amazing local marine life.

The Port Phillip Taxonomic Toolkit is primarily an identification and information resource for scientists and marine enthusiasts, but the images provide some fun and education for all audiences. There are also interactive menus to identify selected species as well as descriptions of characters that make the animals unique.

The project is funded by the Department of Sustainability and Environment's Seagrass and Reefs Program for Port Phillip Bay and will be completed later this year.

Hydrothermal vents

Author
by Kate C
Publish date
24 January 2012
Comments
Comments (1)

Collection Manager David Staples has recently returned from a six-week voyage with a team of British scientists studying the marine life on seamounts and hydrothermal vents in the southern Indian Ocean.

Hydrothermal vents are associated with active spreading centres of tectonic plate boundaries and are often referred to as black (or white) smokers because of the mineral-rich, super-heated fluids they spew into the water column.

A diverse and unique fauna lives in association with the vents and a short clip of what was seen on one of these vents at about 3km depth can be viewed here. Yeti crabs, sea spiders, scaly-foot gastropods, mussels, worms and shrimp can be seen moving quickly at the periphery of these high temperature plumes.

 

Video used with the kind permission of Dr Jon Copley, National Oceanography Centre, Southampton.

Links:

Mountain life beneath the sea

Black smoker in Dynamic Earth

2012 EOL Rubenstein Fellow

Author
by Kate C
Publish date
19 January 2012
Comments
Comments (1)

Dr Joanne Taylor has had a busy few months; just before Christmas the book that she co-edited was published, and now she has been selected as a 2012 Encyclopedia of Life (EOL) Rubenstein Fellow!

This prestigious fellowship is awarded by the Smithsonian Institution to support scientists to upload information about the species they study into the EOL. As a Rubenstein Fellow, Jo will be adding over 400 species of squat lobsters to this amazing resource about the world's biodiversity.

In 2009, Jo started a postdoctorate project to produce the first comprehensive book about this group of colourful crustaceans. The resulting book, The Biology of Squat Lobsters, was published by CSIRO last year.

Dr Jo Taylor Dr Jo Taylor in late 2011 with her hot-off-the-press preview copy of her book, The Biology of Squat Lobsters.
Source: Museum Victoria
 

Congratulations Jo!

Links:

MV News: New squat lobster species

MV News: Butterflies of the sea

Encyclopedia of Life

The Biology of Squat Lobsters, edited by Gary C B Poore, Shane T Ahyong and Joanne Taylor. CSIRO Publishing, 2011.

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