Sharks: As Animals and Individuals

The ancestors of modern sharks were already roaming the oceans 455 million years ago, when green plants were first transforming the land. And now, their presence in the form of more than 470 species split across 14 orders, is woven throughout the marine environment. Sharks are considered vital to oceanic ecology, yet humanity has branded them as mindless killers, and is hunting them into extinction. Yet no one knows what they are really like.

Ecology & Science

A difficulty in obtaining information about the natural behaviour of wild animals is that detailed observations of the activities of different individuals is necessary over long periods of time, and this is especially hard to achieve with sharks.

The True Nature of Sharks

For the first time, affectionate behaviour in a shark has been documented. Jim Abernethy, of Palm Beach in Florida, filmed his reunion with a tiger shark after a separation of two years.

Ecology & Science

Abernethy, owner and operator of Scuba Adventures in Florida, had gained the shark's trust through gentle touches, initially to remove five hooks from her mouth. Since 2003, he has been using this method to remove hooks from many different species of sharks, as described in this former article about him, here.

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Cognition and Self Awareness in Manta Rays

Although born in the landlocked country of Hungary in Budapest, Dr Csilla Ari fell in love with the sea as a child and has never looked back. Today, she is a research associate at the University of South Florida, where she strives to better understand the biology and behavior of manta rays. She has also set up the Manta Memories project, which aims to help end illegal manta ray fishing.

Words:
Edited by Ila France Porcher
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Ecology & Science

X-RAY MAG: How did you become interested in studying the behavior of manta rays?

Some sharks are smart cookies

Bamboo sharks which have been trained in a range of visual discrimination tasks, such as distinguishing between squares, triangles and lines, remembered the learned information for a period of up to 50 weeks, after which testing was terminated despite the absence of reinforcement. This indicate that sharks are capable of long-term memory within the framework of selected cognitive skills.

Ecology & Science

Researching the intelligence of the grey bamboo shark a team of researchers at Rheinische Friedrich-Wilhelms-University in Bonn, Germany showed that sharks could be trained to recognise and remember shapes for an extended period of time.

First juvenile sharks were subjected to three different cognition experiments, one at a time, and then tested to see how long the sharks could remember their training.

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Pain in Fish and Sharks

It was Dr Lynne Sneddon, at the University of Liverpool, who proved scientifically that fish feel pain and suffer. Her team found 58 receptors located on the faces and heads of trout that responded to harmful stimuli. They resembled those found in other vertebrates, including humans. A detailed map was created of pain receptors in fishes’ mouths and all over their bodies.

Words:
Ila France Porcher
Images:
Ila France Porcher
Andy Murch
Dr Lynne Sneddon
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Ecology & Science


The experiment involved the injection of acetic acid, bee venom, or saline solution as a control, into the lips of trout, and those injected with the noxious substances responded with symptoms of pain, while the behaviour of the control group was unchanged. A morphine injection reduced these symptoms.

The relief of the fishes’ symptoms by the pain reliever showed the interconnection between the nociceptors, which sense the tissue damage, and the central nervous system, which recorded the damage as pain. Here was proof that fish are aware of tissue damage as pain.

Fish feel the blues too

Chronic stress can lead to depression and anxiety in fish, German scientists discover.

Ecology & Science

Zebrafish suffering from chronic stress as a result of a genetic mutation showed signs of depression in behavioural tests.

Meanwhile, a doctoral thesis on stress response and frustration in fish by research fellow Marco Antonio Vindas at Norway's Environmental and Life Sciences University has also established that salmon have emotional responses, defined as more or less unconscious reactions in the brain triggered by consuming or positive situations.

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Cognition in Sharks

A difficulty in obtaining information about wild animal behaviour is that detailed observations of different individuals is necessary over long periods of time, and this is especially hard to achieve with sharks. But in the shallow lagoons of French Polynesia, such observation was possible without the encumbrance of scuba gear, and without the problem of the shark disappearing into the depths.

Words:
Ila France Porcher
Images:
Ila France Porcher
Wolfgang Leander
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Ecology & Science

As I learned where and how to look for the local sharks, I focused on blackfin reef sharks (Carcharhinus melanopterus), because they were so easy to find patrolling the shores. But other species, including whitetip reef sharks (Triaenodon obesus), grey reef sharks (Carcharhinus amblyrhynchos), sharptooth lemon sharks (Negaprion acutidens) and nurse sharks (Ginglymostoma cirratum) were present and often observable for long periods, too.

 

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Deep Trust In Sharks

Jim Abernethy, owner and operator of Scuba Adventures, was the dive operator who showed all of the others that sharks are peaceful animals who want nothing to do with humans as a food source.

He spends most of his time with wild sharks during dives from his liveaboard ship, The Shear Water, at remote sites in the vicinity of the Bahamas, and is on land for only about 40 days a year.

Words:
Ila France Porcher
Images:
Jim Abernethy
Ila France Porcher
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Ecology & Science

In order to show people the true nature of sharks on his dives, Jim specifically targeted those with the worst reputations. He was the first eco-tourism guide operator to do so. Soon he was taking divers to see great hammerhead sharks, tiger sharks, bull sharks, oceanic whitetips and lemon sharks. For roughly the first seven years of these interactions, the other operators who have now followed his lead, fought and voiced their opinions that people would soon be dying because of Jim’s foolishness.

 

Does this whale talk?

Researchers in the US have been shocked to discover a beluga whale whose vocalisations were remarkably close to human speech. After seven years in the care of humans a white whale called NOC began, spontaneously, to make unusual sounds. The researchers interpreted the whale’s vocalizations as an attempt to mimic humans.

Ecology & Science

Excerpts from Current Biology, Volume 22, Issue 20, R860-R861, 23 October 2012

The whale lived among a group of dolphins and socialized with two female white whales. The whale was exposed to speech not only from humans at the surface -- it was present at times when divers used surface-to-diver communication equipment.

Fish get emotional too

Have you ever heard of a fish being undecided? Or thought of them as having emotions? Perhaps not. Well, now it turns out that fish, like humans, process information—and perhaps emotions—on different sides of the brain.

Ecology & Science

Now, additional findings lends further credence to the notion that fish do indeed possess emotions and harbour thought processes. It turns out that fish growing up in the wild among predators use their left eye to look at novel objects, while their offspring raised in captivity use the right eye.

 

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