Nicole K

DISPLAYING POSTS BY: Nicole K (11)

Nicole K

Nicole works with museums around Australia to create field guide apps for Apple and Android devices. She has a passion for wildlife and loves that her job involves sharing this passion in such an innovative and engaging way.

Moon gazing across the globe

Author
by Nicole K
Publish date
22 July 2012
Comments
Comments (6)

Your Question: How can my wife and I gaze at the full moon together, but from opposite sides of the globe?

Our enquirer is in Jervis Bay, on the East Coast of Australia. His wife is in Ottawa, Canada. They contacted Museum Victoria to ask if we can help them plan a romantic evening – a full Moon-gazing date on opposite sides of the Earth.

A full moon seen from Ontario, Canada. A full moon seen from Ontario, Canada.
Image: Michael Gil
Source: Wikimedia Commons
 

The next full Moon will occur on the 1st or 2nd of August 2012 (depending on what time zone you are in). In Ottawa, the Moon will rise at 7:55pm EDT (Eastern Daylight Time) on 1 August. It will be at its absolute fullest at 11:27pm and will continue to be visible until it sets on 2 August at 6:28am.

Sadly in Jervis Bay's time zone, the full Moon will occur when the Moon is not visible from that side of the Earth, at 1:27pm AEST (Australian Eastern Standard Time). The Moon will have set that morning at 6:24 and will not rise again until 5:32 that evening.

All is not lost, however. The Moon-watching date can still occur, just not at the precise moment when the Moon is at its fullest. Our couple will just have to wait a few hours.

When the Moon rises on the night of 2 August in Jervis Bay (at 5:32pm AEST), it will be 3:32am in Ottawa (EDT). The Moon will be visible in both places and will remain so until it sets in Ottawa at 6:28am (EDT). This means our two Moon-gazers can watch the still-very-full Moon "together" for nearly 3 hours.

If the idea of getting up so early diminishes the romance from the Canadian perspective, our Moon-gazers can wait a few days – if they are happy to look at a Moon that is no longer full.

On 4 August, the Moon will rise in Jervis Bay at 7:38pm (AEST). It will be 6:02am in Ottawa (EDT). The Moon will be visible in both locations until it sets in Ottawa at 8:48am. Unfortunately this means the Canadian half of our Moon-gazing couple will be looking at the Moon during daylight (the Sun will rise in Ottawa on 4 August at 5:51am).

While arranging this date was tricky, it was only possible because our lovers are not on exactly opposite sides of the Earth. If they were, there would be no chance of viewing the Moon that the same time (for more than an instant and only then if they had a perfect view of the horizon). And one of them would have to be in a boat. Less than 4% of all land on Earth (and no part of the Australian mainland) is antipodal (diametrically opposite) to land: the antipode of Jervis Bay is in the North Atlantic Ocean; the antipode of Ottawa is in the Indian Ocean.

Maps showing Jervis Bay, Australia, and its antipode, in the North Atlantic Ocean. Maps showing Jervis Bay, Australia, and its antipode, in the North Atlantic Ocean.
Image: Antipodes Map
Source: Antipodes Map
 

Links

Melbourne Planetarium: Skynotes

Melbourne Planetarium: Moon Phases

US Navy: Rise/Set times for Sun/Moon

Antipodes Map

timeanddate.com

The biggest whale

Author
by Nicole K
Publish date
8 June 2012
Comments
Comments (0)

Your Question: Is the Whale Shark the biggest whale in the sea?

Whale Sharks are certainly big. The largest recorded was over 12 metres long!

A Whale Shark <i>Rhincodon typus</i> A Whale Shark Rhincodon typus
Image: Shiyam ElkCloner
Source: Shiyam ElkCloner, Wikimedia Commons
 

But Whale Sharks are not whales; they're sharks – the largest shark in the sea. Twelve-metre sharks might sound terrifying, but Whale Sharks are filter feeders. They eat plankton.

  A Whale Shark in the waters off Tofo Beach, Mozambique. A Whale Shark in the waters off Tofo Beach, Mozambique
Image: Jon Hanson
Source: Jon Hanson, Wikimedia Commons
 

The Whale Shark is not, however, the largest shark that ever lived. That was Carcharocles megalodon, popularly known as the Megalodon. Fossils indicate that this species grew to 16 metres long. Unlike the gentle Whale Shark, Megalodon was the stuff of nightmares. A formidable hunter, Megalodon had the largest teeth of any shark, immensely powerful jaws and enormous speed. Thankfully, Megalodon lived 28 to 1.5 million years ago.

The now extinct <i>Carcharodon megalodon</i> had the biggest teeth of any known shark species. Palaeontologists have found fossil Megalodon teeth that are 18cm long! The now extinct Carcharodon megalodon had the biggest teeth of any known shark species. Palaeontologists have found fossil Megalodon teeth that are 18cm long!
Image: Rodney Start
Source: Museum Victoria
 

The largest whale in the sea is the Blue Whale, Balaenoptera musculus. They are truly enormous. There is a complete skeleton of a Blue Whale on display at the Melbourne Museum. It's a whopping 17.2 metres long, but that's actually not that big in Blue Whale terms.

The Pygmy Blue Whale on display at the Melbourne Museum (<i>Balaenoptera musculus brevicauda</i>) The Pygmy Blue Whale on display at the Melbourne Museum (Balaenoptera musculus brevicauda)
Image: Rodney Start
Source: Museum Victoria
 

Melbourne Museum's Blue Whale is a Pygmy Blue Whale (the smallest of the three subspecies of Blue Whale) and it's not fully grown. It's only about half the length of the longest Blue Whale on record, which measured 33.58 metres! That is about as long as a Boeing 737 jet aeroplane. This not only makes Blue Whales the largest whales in the sea; it makes them the largest animal that ever lived!

The comparative sizes of a Blue Whale, a human and a Hector's Dolphin, the smallest cetacean (whales, dolphins and porpoises) The comparative sizes of a Blue Whale, a human and a Hector's Dolphin, the smallest cetacean (whales, dolphins and porpoises)
Image: T. Bjornstad
Source: T. Bjornstad, Wikimedia Commons
 

Sharks and whales are very different creatures. Sharks are fish; most are ectothermic ("cold-blooded") and breathe underwater through gills. Whales are mammals; they are endothermic ("warm-blooded"), breathe air and feed milk to their young. Blue Whales, like (almost) all mammals, give birth to live young – the biggest babies in the world. A newborn Blue Whale is as big as an elephant!

Links

MV Blog: Whale vs Shark

Megalodon: Fossil Shark Tooth

InfoSheet: Shark Teeth

InfoSheet: Blue Whale

Treasures: Blue Whale

Who’s been eating my Easter Eggs?

Author
by Nicole K
Publish date
13 April 2012
Comments
Comments (3)

Your Question: Who or what has been eating my Easter Eggs?

This week, the Discovery Centre was sent some pictures of Easter eggs. It's a sad story: they'd been gnawed, and not by their rightful owner (who was very interested to find out who the culprit was).

Gnawed Easter chocolates Gnawed Easter chocolates
Image: Anonymous
Source: Anonymous
 

Usually we need to see a specimen or a photograph of an animal in order to identify it, but the chocolate thief had left behind a clue – teeth marks.

Gnawed Easter chocolate Gnawed Easter chocolate
Image: Anonymous
Source: Anonymous
 

We sent the photographs to Museum Victoria's Senior Curator of Mammals. He examined the marks and reported that they had been made by the incisors of a small rodent, most likely a House Mouse, Mus musculus. His identification came with another sad story – his own chocolate Bilby had suffered the same fate!

A House Mouse, <i>Mus musculus</i> A House Mouse, Mus musculus
Image: Rodney Start
Source: Museum Victoria
 

Rodents have very distinctive teeth – a pair of incisors in the upper jaw and another pair in the lower jaw. The incisors grow continuously (like our fingernails), so rodents have to do a lot of gnawing to grind them down. In fact, the name "rodent" comes from the Latin words "gnaw" (rodere) and "tooth" (dentis). The gnawing process also acts to sharpen the incisors.

The skull of a House Mouse, <i>Mus musculus</i> The skull of a House Mouse, Mus musculus
Image: Marnie Rawlinson, Cathy Accurso and Ken Walker
Source: Museum Victoria
 

Wild House Mice are primarily granivorous (they eat grains and seeds), but they will eat almost anything. It seems that, like us, they love chocolate.

Happy Easter House Mice!

Got a question? Ask us!

Links:

Introduced Rodents

Collections Online: Easter

The colour of birds' eggs

Author
by Nicole K
Publish date
19 March 2012
Comments
Comments (4)

Your Question: Why are bird eggs so variable in their colours and patterns?

The colour and colour pattern of bird eggs vary enormously from species to species (and often between individuals of the same species, and sometimes between the eggs of the same mother).

  A tray of eggs from Museum Victoria's H.L White egg collection, showing the diversity of patterns and colours for a single species, the Australian Magpie <i>Gymnorhina tibicen</i>. A tray of eggs from Museum Victoria's H.L White egg collection, showing the diversity of patterns and colours for a single species, the Australian Magpie Gymnorhina tibicen.
Image: Michelle McFarlane
Source: Museum Victoria
 

Eggs are made of calcium carbonate, which is white. White is therefore the default colour for bird eggs, but many birds lay coloured or colourfully-patterned eggs. Why?

The colouration of bird eggs can often be explained by the animal's biology and behaviour. The eggs of ground-nesting birds, for example, need to be well-camouflaged to avoid discovery by predators. They are usually coloured and patterned to match the substrate they are laid upon.

The highly-camouflaged eggs of the American Golden Plover <i>Pluvialis dominica</i>, which nests on the ground. The highly-camouflaged eggs of the American Golden Plover Pluvialis dominica, which nests on the ground.
Image: MeegsC
Source: Wikimedia Commons
 

Tree-nesters, on the other hand, usually have blue or green eggs.

American Robin <i>Turdus migratorius</i> eggs in nest The American Robin, Turdus migratorius, which nests in trees, lays bright blue eggs.
Image: Laslovarga
Source: Wikimedia Commons
 

Birds whose eggs are hidden from view (in hollows, burrows or deep nests), or who sit on their eggs continuously throughout incubation, tend to have white eggs.

  The now extinct Paradise Parrot <i> Psephotus pulcherrimus</i>, which laid its eggs in termite mounds, had white, unpatterned eggs. The now extinct Paradise Parrot Psephotus pulcherrimus, which laid its eggs in termite mounds, had white, unpatterned eggs.
Image: Rodney Start
Source: Museum Victoria
 

The patterns on eggs have developed over eons via natural selection – the better the camouflage, the more likely the eggs are to survive and pass on the genes for well-camouflaged eggs to the next generation. Ornithologists have classified egg patterns and given each "style" a name in order to distinguish them: splashed, blotched, spotted, dotted, marbled, streaked, scrawled, overlaid, capped, and wreathed.

Eggs from Museum Victoria's Ornithology Collection Eggs from Museum Victoria's Ornithology Collection
Image: John Broomfield
Source: Museum Victoria

Colour also provides another form of protection: it is thought to act as a sunscreen, protecting the developing foetus from UV light. The addition of colour also strengthens the eggshell. Birds that are calcium-deficient lay thin-shelled eggs, which are more likely to break. Scientists have found that birds that have multiple clutches in a single season have more highly-coloured eggs in the second and subsequent clutches (when the mother's calcium supplies are reduced). Patterned colouration is also more common in areas with calcium-deficient soils.

The specific colours are incorporated into the shell in the final stage of egg development. Blue and green colour comes from a pigment called biliverdin (which is the same pigment that causes green bruises in humans). In egg colouration, biliverdin comes from bile; the red and brown colour on eggs comes from protoporphyrins, which comes from blood.

The Red-vented Bulbul <i>Pycnonotus cafer</i> lays red eggs. The Red-vented Bulbul Pycnonotus cafer lays red eggs.
Image: J. M. Garg
Source: Wikimedia Commons
 

Australia's native birds are protected. It is illegal to collect eggs or to interfere with birds' nests without a permit. Details of regulations and permits can be obtained from the Department of Sustainability and Environment.

Links:

Museum Victoria's Ornithology Collection

H.L. White Collection of Australian Birds’ Eggs

The evolution of egg colour and patterning in birds

Australian Magpie Eggs

The science of poo

Author
by Nicole K
Publish date
22 January 2012
Comments
Comments (3)

Your Question: Why do scientists study animal poo?

Poo is truly fascinating stuff. Each deposit contains a minefield of information about its owner and the environment it lives in.

Animal poos (scats) come in a multitude of different shapes and sizes. Each species produces its own unique parcels. You can therefore discover which species are present in an area (and how abundant they are) by looking at what they leave behind.

The square droppings of a Common Wombat, <i>Vombatus ursinus</i> The square droppings of a Common Wombat, Vombatus ursinus
Image: Alan Henderson
Source: Minibeast Wildlife
 

The relative size of a deposit can also give you an idea of the age/size of he/she who dunnit. Sometimes, it's even possible to determine the sex and reproductive receptivity of the animal (by the smell).

The condition of the scat (taking recent weather conditions into account) will tell you how recently the animal was there – if it's still fragrant and sticky, you know you're fresh on the trail.

An animal's poo can also reveal the diet of the depositor. Long-term studies of scats can provide information about how animals' diets change over time and the seasonal abundance of their food sources.

A broken-up scat of a Thorny Devil <i>Moloch horridus</i>, revealing that  it has fed exclusively on ants. A broken-up scat of a Thorny Devil Moloch horridus, revealing that it has fed exclusively on ants.
Image: Alan Henderson
Source: Minibeast Wildlife
 

The scats of carnivorous (meat-eating) animals can be an invaluable source of information about the presence and abundance of their prey species. Fur, teeth and bones are not usually digested as they pass through the digestive system and come out relatively intact. As foxes and owls are far better at finding small animals than we are, scats can contain crucial records for scientists studying endangered species.

The scat of a European Red Fox <i>Vulpes vulpes</i> The scat of a European Red Fox Vulpes vulpes
Image: Karen Rowe
Source: Museum Victoria
 

Poo is also a useful indicator of animal health. Scats contain parasites, hormones and DNA (in the animal's own skin and hair cells). Scientists can therefore use the clues in poos to monitor infections, perform genetic analyses and gather information on stress levels and reproductive state, all without touching or even seeing the animal.

Got a question? Ask us!

Links:

Square Poo

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Updates on what's happening at Melbourne Museum, the Immigration Museum, Scienceworks, the Royal Exhibition Building, and beyond.

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