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If you are a seal, you thought you were safe from the great white sharks (Carcharodon carcharias) in kelp. New research shows that you are wrong.
A great white shark marked by the team led by Oliver Jewell.
Photo provided by Oliver Jewell
A new study led by Oliver Jewell, PhD student at Murdoch University, was recently published in the journal & nbsp;Royal Society Biology Letters& nbsp; Jewell and his team used camera tags to film white sharks feeding in the kelp forests of South Africa, showing an agility that is not usually associated with these large predators . The team gathered 28 hours of footage of the eight sharks it tagged and used accelerometers and magnetometers to create pseudo tracks and confirm that sharks were actually hunting in kelp forests … and even captured part of the video hunt!
"The study was done as a result of another work we were doing on sharks in South Africa," said Taylor Chapple, a researcher at Hopkins Marine Station and one of the co-authors. "We were initially present to look at the cinematic predator behavior of the white shark, but when we saw the images of the camera tags, we realized that the sharks were doing something amazing: they were swimming in kelp rather than all around."
Chapple commented that we do not know the predatory behavior of great white sharks on the high seas, but simply what we see around seal colonies, which is usually an ambush since the majority of their prey are very mobile. What surprised the team was that sharks spent a lot of time in kelp and practically eating their food. Although the scientists did not see any predation on camera, they captured a video of Cape fur seals (Arctocephalus pusillus pusillus) displaying predator avoidance behavior. The film clearly shows that kelp is not the barrier to white sharks that it was supposed to be!
In fact, this study shows that our attempts to describe these incredible predators from limited bait or surface interactions are more likely than they are to miss a significant part of their biology and behavior. "This study shows that white sharks are not the one-dimensional hunters that hug seals on the surface, and these animals and their behaviors are much more complex and dynamic than most people attribute to them, and it is only thanks to an adaptation of new technologies that we can really begin to fully understand them. " said Chapple.
Snapshots taken from a 10-minute recording show a large white shark swimming across a kelp forest, which previously was believed to be a barrier for predators. We see here a shark hunting Cape fur seals, shown in figures A to F (red arrows). The seal reacted by laying on the bottom of the sea and blowing bubbles (Figure C). The figures below illustrate the shark's journey through kelp (Figure G) as well as its angle of rotation and depth (Figure H).
Letters of biology; Murdoch University
This is not the only secret that great white sharks have hidden! New search directed by Lecturer Liza Merly& nbsp; from the University of Miami (UM)& nbsp;Rosenstiel School of Marine and Atmospheric Sciences& nbsp; found high levels of mercury, arsenic and lead in blood samples of great white sharks in South Africa. These levels, toxic to other animals, do not seem to have a negative impact on the health of sharks or their immune system. & Nbsp; "The results suggest that sharks may have an inherent physiological protection mechanism that mitigates the adverse effects of heavy metal exposure," Merly said in a press release.
But how did these sharks get such levels of toxicity of these heavy metals? & Nbsp; "As predators, sharks bio-accumulate toxins in their tissues via the food web from the prey they eat," he said.& nbsp;Neil Hammerschlag, co-author of the study and associate professor of research at UM Rosenstiel School and Abess Center for Ecosystem Science & amp; Policy. "Thus, by measuring the concentrations of toxins, such as mercury and arsenic, in the blood of white sharks, they can serve as" ecosystem indicators "for the health of humans. ecosystem, with implications for humans.Basically, if sharks have high levels of toxins in their tissues, it is likely that the species they eat below them will also have toxins, including fish that humans eat. "
It is not only sharks in the South African region that have this bioaccumulation of toxins. & Nbsp;In a study published in the journal ToxinsThe Hammerschlag research team examined fin and muscle tissue samples from 10 shark species found in the Atlantic and Pacific oceans to determine the concentration of two toxins – mercury and β-N-methylamino-L-alanine (BMAA). Both have been detected in the fins and muscles of all these sharks, and recent studies have associated BMAA with neurodegenerative diseases such as Alzheimer's disease and amyotrophic lateral sclerosis (ALS). & Nbsp;
The team, led by Oliver Jewell, tagged a great white shark in South Africa.
Photo provided by Oliver Jewell
For this latest study, 43 great white sharks were sampled as part of the OCEARCH expedition in 2012. "To collect the samples, white sharks were carefully reared on a specialized platform, while biologists took blood samples and body measurements prior to sample collection. labeled and published, "explained Chris Fischer, chief of expedition and founding president of& nbsp;OCEARCH, in the press release.& nbsp; This study provides the first published report on heavy metal blood levels in wild sharks and provides a baseline for heavy metal levels in the blood of white sharks in South Africa. & nbsp;
It seems that we can really call great white sharks "fastballs" … when they want to swim fast, that's it.
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If you are a seal, you thought you were safe from the great white sharks (Carcharodon carcharias) in kelp. New research shows that you are wrong.
A great white shark marked by the team led by Oliver Jewell.
Photo provided by Oliver Jewell
A new study led by Oliver Jewell, PhD student at Murdoch University, was recently published in the journal Royal Society Biology Letters; Jewell and his team used camera tags to film white sharks foraging in the kelp forests of South Africa, showing an agility that is not usually associated with these large predators. The team gathered 28 hours of footage of the eight sharks it tagged and used accelerometers and magnetometers to create pseudo tracks and confirm that sharks were actually hunting in kelp forests … and even captured part of the video hunt!
"The study was conducted as a result of another work we were doing on sharks in South Africa," said Taylor Chapple, research scientist at Hopkins Marine Station and one of the coauthors. "We were initially there to look at the cinematic predator behavior of the white shark, but when we saw the images of the camera tags, we realized that the sharks were doing something amazing: they were swimming in the kelp rather than all around. "
Chapple commented that we do not know the predatory behavior of great white sharks on the high seas, but simply what we see around seal colonies, which is usually an ambush since the majority of their prey are very mobile. What surprised the team was that sharks spent a lot of time in kelp and practically eating their food. Although the scientists did not see any predation on camera, they captured a video of Cape fur seals (Arctocephalus pusillus pusillus) displaying predator avoidance behavior. The pictures clearly show that kelp is not the barrier to white sharks that we thought we were!
In fact, this study shows that our attempts to describe these incredible predators from interactions limited to bait or surface are more likely than not to miss much of their biology and behavior. "This study shows that white sharks are not the one-dimensional hunters that hunt seals on the surface, and that these animals and their behaviors are much more complex and dynamic than most people attribute to them." Only adaptations of new technologies can really help us, start to understand them fully, "said Chapple.
Snapshots taken from a 10-minute recording show a large white shark swimming across a kelp forest, which previously was believed to be a barrier for predators. We see here a shark hunting Cape fur seals, shown in figures A to F (red arrows). The seal reacted by laying on the bottom of the sea and blowing bubbles (Figure C). The figures below illustrate the shark's journey through kelp (Figure G) as well as its angle of rotation and depth (Figure H).
Letters of biology; Murdoch University
This is not the only secret that great white sharks have hidden! New research conducted by Liza Merly, Senior Lecturer at the University of Miami (UM) The Rosenstiel School of Marine and Atmospheric Sciences has discovered high levels of mercury, arsenic and lead in blood samples taken from great white sharks in South Africa. These levels, toxic to other animals, do not seem to have a negative impact on the health of sharks or their immune system. "The results suggest that sharks may have an inherent physiological protection mechanism that mitigates the adverse effects of heavy metal exposure," Merly said in a press release.
But how did these sharks get such toxic levels of these heavy metals? "As top predators, sharks bio-accumulate toxins in their tissues via the food chain of prey that they eat," he said. Neil Hammerschlag, co-author of the study and Associate Research Professor at UM Rosenstiel School and Abess Center for Ecosystem Science and Policy. "Thus, by measuring the concentrations of toxins, such as mercury and arsenic, in the blood of white sharks, they can serve as" ecosystem indicators "for the health of the ecosystem; which has consequences for man.But basically, if sharks have high levels of toxins in their tissues, it is likely that the species they eat below them will also have toxins, including the fish that humans eat. "
It is not only sharks in the South African region that have this bio accumulation of toxins. In a study published in the journal ToxinsThe Hammerschlag research team examined fin and muscle tissue samples from 10 shark species found in the Atlantic and Pacific oceans to determine the concentration of two toxins – mercury and β-N-methylamino-L-alanine (BMAA). Both have been detected in the fins and muscles of all these sharks, and recent studies have associated BMAA with neurodegenerative diseases such as Alzheimer's disease and amyotrophic lateral sclerosis (ALS).
The team, led by Oliver Jewell, tagged a great white shark in South Africa.
Photo provided by Oliver Jewell
For this latest search, 43 great white sharks were sampled as part of the 2012 OCEARCH expedition. "To collect the samples, the white sharks were carefully raised on a specialized platform, while the biologists took blood samples and body measurements before the sharks were tagged and released," said Chris Fischer. expedition leader and founding president of OCEARCH, in the press release. This study provides the first published report on heavy metal blood levels in wild sharks and provides a baseline for heavy metal levels in white shark blood in South Africa.
It seems that we can really call the great white sharks "fast balls" … when they want to swim fast, that's it.