sharks

Apex marine predators choose whom they hang with, researchers reveal. White sharks form communities, researchers have revealed. Although normally solitary predators, white sharks (Carcharodon carcharias) gather in large numbers at certain times of year in order to feast on baby seals.

These groupings, scientists had assumed, were essentially random – the result of individual sharks all happening to turn up in the same area, attracted by abundant food.
Now, however, a group of researchers including behavioural ecologist Stephan Leu from Macquarie University in New South Wales, Australia, have used photo-identification and network analysis to show that many of the apex predators hang out in groups which persist for years.

To make the findings, Leu and colleagues including Charlie Huveneers and others from Flinders University and the Fox Shark Research Foundation, both in South Australia, as well as French government research organisation CNRS, spent four and half years taking multiple photographs of almost 300 white sharks gathered around a seal nursery in the Neptune Islands in the Great Australian Bight.

Through the images they were able to identify individual sharks and, to their surprise, found that many were seen in proximity to specific others far more often than chance would determine.

“Rather than just being around randomly, the sharks formed four distinct communities, which showed that some sharks were more likely to use the site simultaneously than expected by chance,” says Dr Leu.

“The numbers varied across time, and we suggest that sex-dependent patterns of visitation at the Neptune Islands drive the observed community structure.
Our findings show that white sharks don’t gather just by chance, but more research is needed to find out why."

The paper – published in the journal Behavioural Ecology and Sociobiology – is the latest research to change perceptions about the behaviour of apex fish.

In August 2019 another group of scientists, led by Macquarie University’s Robert Perryman, established that manta rays (Mobula alfredi) also have structured and persistent social relationships that can be described as communities.

A jaw-full of mega shark teeth – rare evidence that a shark twice the size of a Great White stalked Australia's ancient waters – is to be unveiled at Melbourne Museum on today, Thursday 9 August. Usually shark teeth are found singly, but this time they have the whole set for the gigantic Great Jagged Narrow-Toothed Shark.

A prehistoric shark feast, the 9m long Great Jagged Narrow-Tooth Shark becoming a meal for several Sixgill Sharks. Credit: Peter Trusler / Philip Mullaly, the local Ocean Grove resident who found the mega shark teeth with Dr Erich Fitzgerald. Credit: Museums Victoria

Victorian Fossil Find Uncovers Prehistoric Leftovers of Colossal Shark Feast

A visit to his local beach will never be the same again for Philip Mullaly. The keen-eyed fossil enthusiast has found an extraordinary set of shark teeth - evidence that a shark nearly twice the size of a Great White once stalked Australia’s ancient oceans. The citizen scientist made the find in Jan Juc, a renowned fossil site along Victoria’s Surf Coast.

“I was walking along the beach looking for fossils, turned and saw this shining glint in a boulder and saw a quarter of the tooth exposed. I was immediately excited, it was just perfect and I knew it was an important find that needed to be shared with people,” recounts Mr Mullaly.

Up to 7 cm long, the teeth have been identified as being from an extinct species of mega-toothed shark - the Great Jagged Narrow-Toothed Shark (Carcharocles angustidens) - which could grow to more than 9-metres long, almost twice the length of today’s Great White Shark.

This shark stalked Victoria’s ancient sea approximately 25 million years ago, during the late Oligocene epoch. It was the top predator and would have preyed on small whales.

Recognising the significance of the discovery, Mr Mullaly contacted Dr Erich Fitzgerald, Senior Curator of Vertebrate Palaeontology at Museums Victoria with an offer to donate the teeth to Museums Victoria’s collection, an offer gratefully accepted.

Almost all fossils of sharks worldwide are just single teeth, so it is extremely rare to find multiple associated teeth from the same shark.

This is because sharks, who have the ability to regrow teeth - lose up to a tooth a day. Cartilage, the material a shark skeleton is made of, does not readily fossilise.

“These teeth are of international significance, as they represent one of just three associated groupings of Carcharocles angustidens teeth in the world, and the very first set to ever be discovered in Australia,” Dr Fitzgerald explains.

“By donating his discovery to Museums Victoria, Phil has ensured that these unique fossils are available for scientific research and education both now and for generations to come. This is absolutely essential for documenting and preserving Australia’s prehistoric history.”

Realising Mr Mullaly's haul was all from the same species, Dr Fitzgerald suspected that the teeth came from one individual shark and there might be more teeth still entombed in the rock at Jan Juc.

So, in December 2017 and January 2018, Dr Fitzgerald led a team of Museums Victoria palaeontologists, volunteers, associates and Mr. Mullaly on two expeditions to excavate the site.

Battling summer heat, and with only a tiny window each day to access the site at low tide, the team dug out the entire boulder, collecting more than 40 teeth.

Most of the teeth belonged to the giant shark Carcharocles angustidens, but in addition, several smaller teeth were found revealing something even more surprising...

Comparison of Carcharocles angustidens and a Great White Shark. Credit: Peter Trusler

In the boulder, were several teeth of a smaller shark, the Sixgill Shark (Hexanchus).

According to Museums Victoria palaeontologist Tim Ziegler, these came from several different individuals and would have become detached from their jaws as they were scavenging on the huge carcass of the Carcharocles angustidens after it died.

“The teeth of the sixgill shark work like a crosscut saw, and tore into the Carcharocles angustidens like loggers felling a tree. The stench of blood and decaying flesh would have drawn scavengers from far around.

“Sixgill sharks still live off the Victorian coast today, where they live off the remains of whales and other animals. This find suggests they have performed that lifestyle here for tens of millions of years.”

This new discovery cements Jan Juc as one of Australia’s most important fossil sites, as it continues to provide us with unique insights into the deep history of Australia’s marine life including whales, dolphins, sharks and countless smaller marine animals.

The general public will have a rare and limited opportunity to see these incredible teeth specimens when they go on display at Melbourne Museum as part of National Science Week on Thursday 9 August. The display will be open until Sunday 7 October.

The Mega Shark Fossil Find display will feature all 45 fossil shark teeth, as well as state-of-the-art life-sized 8-metre long digital animation which will appear to swim around the gallery floor surrounding the showcase.

For National Science Week, Melbourne Museum has programmed a suite of palaeontology events, including fossil identifications, Jurassic Park 3D in IMAX (18 Aug), (19 Aug) and The Giants of Palaeontology talk with Dr Fitzgerald and fellow Museums Victoria palaeontologist Dr Tom Rich (19 Aug).

The Mega Shark Fossil Find opens to the public as part of National Science Week on Thursday 9 August, and will run until Sunday 7 October.

Museums Victoria’s field research at Jan Juc is carried out with the support of the Department of Environment, Land, Water and Planning, Surf Coast Shire Council and the Great Ocean Road Coast Committee.

SYDNEY: Just a week after another fatal shark attack in Australia, University of Sydney PhD candidate and shark policy expert Christopher Neff is leading a world-first project to help reduce the public’s fear of sharks.

The project, entitled ‘Taking the Bite Out of Jaws: An evidence-based look at public fear of sharks’, is part of the Shark Week activities running until Saturday this week at Sea Life Sydney Aquarium.

The research will use 10 iPad touch-screens to survey Aquarium visitors when they enter and exit the Aquarium’s ‘Shark Valley’ exhibit to register their perceptions of sharks after witnessing different science- and conservation-based messages.

“Movies and television have made scaring people about sharks the easy part. This research is trying to find a new way to reduce public fears of sharks,” said Neff.

“This study uses iPads to survey people before and after they walk through an underwater tunnel with sharks swimming over them. We are looking at what messages lower people’s concerns about sharks because this can create more opportunities for shark bite prevention and conservation education.”

Following the week of survey collection, the statistical data will be analysed to seewhich messages are the most effective to reduce fears. Once the results have been reviewed, the survey will be adjusted and the project will be tested at other aquariums around the world.

Shark Week activities at Sea Life Sydney Aquarium are supported by the Sea Life Conservation Fund and the Save Our Seas Foundation.

For other candobetter.net articles on sharks see: the Secret life of sharks by Peter Kimley (book review) and "Jaws 2009, Coming soon to your shores" about how the monster shark in Jaws was actually a metaphor for property developers ruining local democracy and landscape.

Book Review

A. Peter Klimley, The Secret life of Sharks, Simon & Schuster, New York, 2003.

“There was a massive procession of whales and fish passing by us and moving in the direction of Seamount Espiritu Santo. The first in this animal parade were twenty or so pilot whales. Then came a crescent-shaped formation of dolphin-fish. Then followed a large school of tuna. Were we privileged to be witnessing the slow migration of this whole assemblage toward its next destination, Espiritu Santo? Could this massive assemblage of whales and fishes be using the magnetic lineation on the seafloor below to guide its procession?” Peter Klimley, The Secret Life of Sharks, p.125.

Ichthyologist (fish scientist) Peter Klimley has an ethologist’s eye for communities in the sea. His book describes his own research into shark behaviour, particularly into schooling habits, communication, and navigation methods of particular species. The navigation methods are mind-spinningly different from our own. Klimley concentrates on the navigation skills of schools of hammerhead sharks in the Gulf of Mexico (more below). This focus also leads him to observe ecological communities on the move along the same lines, in the extraordinary procession of whales and fish described above, moving between geological saliences where plant species and therefore fish, aggregate.

Repairing the damage from Benchley's Jaws

When I was about 9 years old, my favorite book - long lost - was by Jeannie Lewis, My life as an ichthyologist. This was a rollicking tale of a woman's adventurous career amid the brightly coloured waters of the South Seas. It was illustrated with perky drawings of kinky little animals, like trigger-fish. It also described strange legends of frogs and stones falling from the sky into thatched huts, and revealed some secret women's business.

I wanted to be an ichthyologist because of it, but unfortunately I read Peter Benchley's Jaws Doubleday & Company, NY, 1974, which almost ruined my enjoyment of swimming in the sea. I now see it as a book about developers taking over a town and corrupting its government, but the scene where a huge serrated man-trap silently surges up beneath the slightly drunk swimmer, has imprinted my mind indelibly.

To cope with this after-image of human swimmers as shark cocktails, I have tried to learn more about sharks.

Seeing fish as individuals

What made me buy Peter Klimley's scientifically rich Secret Life of Sharks, as I riffled through its pages in a Brisbane store that markets remaindered books, was noticing how the author made a personal connection with one of the sharks he studied. He had taken Huey, a foot-long baby grey nurse, from the 'Shark Channel' in the Miami Seaquarium, because he felt sorry for him, knowing his certain fate was to be eaten by other sharks in the Channel. The author also has a strong aesthetic sense of nature.

"One day, I couldn't restrain myself from scooping one up in a dip net to keep in an aquarium above my desk at the marine laboratory. The baby shark that I held in my hands was very attractive. It was brown with alternating dark and light bands, each of which merged into the other with a gradual shift in the hue of its color. Speckling his body were small green iridescent spots. Both the bands and spots would gradually disappear as he grew up. Protruding from the forward edge of his nostrils were long barbels. These gave the foot-long nurse shark, whom I named Huey, a comical touch.

Klimley takes the reader on amazing journeys

Klimley is able to take the reader to some amazing places and share with us some unique experiences, such as feeling as if we are also looking up at the sun-silhouetted bodies of sharks above us in the gulf of Mexico. Another strength of this book lies in the author’s skill in relating clearly, but in an interesting and useful way, the details of his experimental work measuring, testing and describing the behaviour of the creatures he swims amongst. We are introduced to a variety of scientific fields and their application in real life. We also get a good picture of the behaviour of the teams of human observers and neighboring fishermen, of the techniques, skills and the risks required to do unusual tasks in unusual environments.

Routine feats of endurance

Feats of endurance were routinely required in much of this marine field-work. These are interesting for the scope they reveal in human performance, especially that of young men, for instance doing repeated free dives to around 100 feet below in order to tag hammerheads. On one occasion, in another situation, the author notices a colleague becoming disoriented and clumsy from fatigue, whilst swimming against a current in choppy waters, and he comments on how unconscious competition between himself and the other swimmer probably contributed to this.

Shark attacks described in accumulated detail

Klimley describes a shark attack on a collegue in the same way he describes shark attacks on seals and other prey. The account is humbling because it is totally unjudgemental, unanthropocentric. (The diver survived.) This doesn’t mean that the author has no feelings for his colleages, for he reveals a strong and appropriate concern in many situations. The difference is that this account falls into a range of accounts from scientific observation of many many feeding behaviours over a period of time off the coast of a remote island where Great White sharks made their living. We are also grateful to learn what turns sharks on and what doesn’t, and the posture they display when they feel challenged.

Klimley outlines his hypotheses and then instructively describes the problems he encounters looking for ways to test these. Any student would benefit from these descriptions. The author shows versatility and breadth in his scientific knowledge, particularly of earth physics.

Stunning findings on undersea animal navigation

Perhaps the most stunning research he describes are his findings on the use of magnetic lineation on the sea-floor to navigate. In this he demonstrates a huge new dimension to life. He shows that some sharks and other sea-creatures have senses which we humans, and most terrestrial animals simply don't suspect exist. He verifies this sensory world through painstakingly devised techniques to measure, repeat, record and locate patterns of behaviour in individuals in hammerhead schools near the Espiritu Santu Seamount in the south western coast of Mexico. He repeats his measurements at night.

"[Salmon] were certainly skilled navigators, but the scalloped hammerheads might be even better: they made nightly migrations far out into the featureless ocean and were able to find the seamount every morning. (…) There was simply no light to guide the shark … Yet she was swimming away from the seamount in a perfectly straight line."

Klimley describes the different forms of magnetization: "The total magnetic field measured at the earth’s surface is the sum of two magnetic sources, the earth’s inner core and its outer crust. Circulation of electrically conductive molten metals in the earth’s core creates the [very strong dipolar magnetic fields of the (…) north and south poles. (…)"

The author explains that magnetic minerals (oxides of iron and titanium) produce smaller dipolar magnetic patterns on the earth, including undersea. Because of the volcanic origin of underwater mountains you often get such dipolar patterns in different locations on the same sea-mount because the north-south poles reversed their polarity between one eruption and the next. This means that the magnetic particles in those eruptions remain aligned according to the prevailing polarity of the north-south poles at the time of eruption.

30 years of diving with sharks tells us another story about ourselves.

People should not be surprised to hear that, as this story of one man's study of sharks is told, over a period of about 30 years, between the early 1970s and the beginning of the 21st century, the numbers of sharks decline markedly.

Sharks are threatened by human predation because it takes them a long time to mature reproductively and they are often taken by fishing well before they reproduce.

Handy tips to avoid the sharp end of sharks

There are many handy tips for those of us concerned to avoid being on a shark's menu.

Here are some humorous ones I have synthesised from Klimley's more sober observations:

Keep your fat to muscle ratio low: To generalize over shark-species, they seem to prefer prey with high fat-content, and will frequently spit humans out because their fat-content compares poorly with preferred prey, such as seals.

Perfect your killer-whale vocalisations: Several shark species have been shown to react with extreme fear to the sound of an orca’s vocalizations.

Wear black and white swimsuits: In some of his early interactions with sharks, Dr Klimley adapted his wetsuit and wore a fin to make himself look like a killer whale (orca) and some species of sharks in certain circumstances made themselves scarce when they saw him. Perhaps this idea might inspire some swimsuit and wet-suit fashion designers.

A. Peter Klimley is an associate professor at the University of Davis, California https://wfcb.ucdavis.edu/www/faculty/Pete
[24reads-to-edit smn]

The final version of Jaws dwarfs all the others. This new monster is eating towns up alive. This is not just a battle to the death; this is WAR! In the novel, Jaws, the monster was not really a white pointer shark, it was the property development lobby, which metastasized with the colonisation of a modest fishing town by rich people from other places. Developers drew power from the wealthy tourists and sea-changers. They took over the original fishing town for their own purposes and democracy seemed fatally wounded. Right to the point of the shark (the developers) trying to eat the boat (symbol of the fishing industry which had begun the town). Until an odd bunch of people had the guts to stand up to the big developers.

How many people stopped swimming in the sea after reading the Peter Benchley blockbuster of the 1970s, Jaws? Well you can stop looking down now, because there is a much worse enemy and it has two legs.

In the novel, Jaws, the monster was not really a white pointer shark, it was the property development lobby, which metastasized with the colonisation of a modest fishing town by rich people from other places.

Developers drew power from the wealthy tourists and sea-changers. They took over the original fishing town and the mayor listened to them more than he did to the citizens. The local police became confused about their powers because of this. People were encouraged to risk their lives for the sake of 'economic growth'. They shut up in case they sounded stupid.

Sound familiar?

Because the mayor's ear was tuned to the tourism and development business it was tuned out to local democracy.

Local government and democracy looked as if it was fatally wounded. Right to the point of the shark (the developers) trying to eat the boat (symbol of the fishing industry which had begun the town). Until an odd bunch of people had the guts to stand up to the big developers. But were those people really so odd or was the rest of the town in a trance?

Hard to imagine anything worse than that shark, isn't it? But, since 1975 the problem has got so much bigger. The monstrous cold black-eyed machine of 'economic development'; sub-prime species, which only exists to patrol the world in search of food for its disgusting and insatiable appetite is now so big that it is engulfing the world. Destroying whole forests. Digesting democracies in a single livid gulp.

Are you ready to stand up to the developers?

You will need to understand ecology, be able to think against the tide, and get your ideas somewhere else besides television and the Murdoch and similar newspapers, because all these media-sources are major real-estate marketers and barrack for population growth.

In an article published on Freedom Arizona, bankruptcy is reportedly racing through the US, threatening governments at all levels.

46 Of 50 States Could File Bankruptcy In 2009-2010

"There is a high chance a majority of the States within the United States of America could file for Chapter 9 bankruptcy. There are currently 46 states with high budget deficits, Arizona being one of them."

"The ... State of Arizona has 90 to 120 days before they completely run out of money. After that, all bills and tax refunds owed to the citizens will go unpaid. ... With neighboring California on the verge of bankruptcy this year, many States will follow in their steps.

"Many States are already scurrying to cut unwanted costs, cut State-funded programs, raise taxes, not issue tax refunds to their citizens, and borrow money just to survive in 2009.

[...]Many banks — the same banks the Fed bailed out — are refusing to loan money to the States and their Treasury agencies.

At the Center on Budget and Policy Priorities website you can see that 46 of the 50 States are clearly in the financial red.

Freedom Arizona comments, "It’s very possible you’ll see the end of the United States as we know it. If the Fed doesn’t bailout the States when their cash dries up and the banks don’t loan them money, then our States will be left in financial ruin. This would be a tragic and unprecedented event never experienced in the United States. No State has ever filed bankruptcy, but it could be coming to a State near you this year."

"We are on the brink of something far worse than the Great Depression," the article concludes.

Canada, Australia and Britain are in the same ... um... boat

Unfortunately Canada, Australia and Britain have all fallen prey to similar population-growth-and-land-speculation systems. Spain has also managed to become the premier basket case in Europe due to its having abandoned its economy to the construction industry and now has 20% unemployment.

Land sharks belong in prison

We have to get rid of the property development lobby which is running our country and ruining our ability to democratically restrain such excesses. We have to find some real ecological heros. We won't find them in the traditional places. They won't be ordinary people. They won't be well-known. They will come from the outside.

We have to find or make laws to stop our governments from engineering population growth against our welfare and from serving our countries and citizenship up to the developers and bankers. Work that is necessary can be shared. Wealth can be shared. Sharks are just fine in the sea, but property developers and their hangers-on belong in zoos, museums and prisons.