True: Sharks Can Be Stared Down
While filming Blue Water, White Death in 1969, 200 km off the South African coast, we left the safety of our cages, which we tied to a dead whale, and fought off hundreds of large sharks, eventually making a place for ourselves in the midst of the pack. We taught those sharks, all of them extremely dangerous, respect in a few frantic minutes.
The first beasts to approach us were hit by my shark billy , bashed by Rons metal camera housing, or punched in the gills by fellow cameramen Stan Waterman and Peter Gimble. When they bumped us, we bumped them back harder. Not one of us backed off. I waited to be bitten, torn apart, or to see my companions torn apart, and wondered what I would do when it happened. There was no fear, just a feeling of excitement and aggression.
It was like rewinding time. We had entered a primeval world, unchanged in millions of years, and made a place for ourselves at the banquet. Somehow the knowledge spread throughout the shark pack that if confronted, these four bubble-blowing, clumsy creatures would fight. Apex predators are used to their prey trying to escape, not standing their ground and fighting back.
But we fought back and became accepted as part of the pack. Surrounded by very dangerous sharks, we swam with them, even to where they were feeding on the whale and although we were sometimes pushed aside, we did not again feel threatened.
How Do Sharks Smell
- How do sharks smell?
There is a general consensus among marine scientists that sharks have an exceptional sense of smell. This is definitely very true and absolutely necessary for their survival. The idea though that sharks have super sniffers that they use to sniff out the minutest amounts of blood in vast bodies of water is, for the most part true, but greatly embellished. Let’s take a closer look at sharks’ sense of smell this Sharktober.
Lets first look at how sharks use their noses to sniff out prey, blood and other interesting titbits in the ocean. Smell is incredibly important to sharks and how they use this sense is quite fascinating. Just under the snout of a shark are two small openings, or nares . Each nare consists of two more openings. Water goes in the one opening and out the other. Inside the nasal cavities are a series of sensitive skin folds. Water passes over sensory cells within the skin folds. These cells pick up the scents in the water and then send signals to the sharks brain. In the sharks brain, the olfactory lobes kick in and analyse the scents, which can be those of a potential mate or prey. With smell being so very important to sharks, it is no surprise that about two-thirds of a sharks brain is made up of olfactory lobes. From here, it is up to the shark to decide if it wants to pursue the scent or not.
Sharks Have Small Brains And Are Not Intelligent
Ajemian: This is a common misconception. Sharks their brain size relative to their body weight is actually comparable to some mammals. They are capable of learning. The myth that sharks are mindless eating machines has been dispelled. They actually eat less than you think. They can go weeks without eating. They eat three percent of their body weight a day, which isnt much. You can get sharks to respond to some types of stimulus, such as giving a reward they have some cognitive capacities. Not like humans, but theyre not mindless.
We rate this FICTION. Sharks can exhibit complex social behavior and some species can communicate with body language, live in groups and even hunt in packs. Sharks and rays have some of the largest brains among all fish, with brain-to-body ratios similar to birds and some mammals.
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Plausible: Sharks Are Attracted By Blood
It has been said that human blood will attract a shark from kilometres away. This hasnt been our experience, but perhaps weve never bled enough to be attractive. We know that a harpooned whale bleeding its life into the open ocean as it cries in agony can attract hundreds of large, very dangerous sharks.
Much to the horror of sailors in the water after vessels have sunk, oceanic whitetip, blue and silky sharks can appear like magic from the depths. The former two have no instinctive fear of humans they have evolved to eat large, wounded or thrashing animals in the water and are responsible for more human deaths than all the other so-called dangerous sharks worldwide. Like many other sharks, they can be trained, and quickly.
Clasper And Clasper Spurs
In the adult white shark, the claspers are scroll-shaped heavily calcified appendages that protrude 3540 cm from the medial margin of the pelvic fin. They are robust structures, 57 cm in diameter . Each bears a sharp, conical, calcified, and dentine-covered spur or claw that folds out of the distal surface as the terminal cartilages open. Apparently, the spine serves to lock and hold the clasper in the vagina . The condition of clasper spurs varies from individual to individual. Juveniles have an undifferentiated soft spur that does not protrude from the clasper when the terminal cartilages are pulled back. The spurs of one or both adult claspers can be completely enveloped in a tough epidermal sheath, as was seen in a 497 cm TL male. Dissection of the thick sheath of large white sharks exposes a sharp, hard, conical spur. The right spur of a 517 cm TL male had 8 mm of hard pointed tip exposed, but the left spur was blunt, naked to the base, and encrusted with irregular concretions of calcium. However, it was not smaller or obviously broken . A similar irregular spur was noted by Matthews on an adult basking shark, whose claspers are very similar in form to those of the white shark.
FIGURE 3. Distal end of the adult right clasper. The terminal cartilage is splayed open, and the spur is erect.
MALCOLM P. FRANCIS, in, 1996
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What Does A Persons Brain Look Like When Deciding To Smoke Weed
Decision-making is a complex process thatâs not limited to just one part of the brain. A 2015 fMRI study published in the journal Neuropsychopharmocology centered on 17 participants as they made the decision to smoke. The results suggested that the choice to smoke marijuana is accompanied by a consistent level of activation in a range of brain regions.
Brain imaging showed activation in the subjectsâ dorsal striatum, insula, posterior parietal regions, anterior and posterior cingulate, and dorsolateral prefrontal cortex as the person decided to smoke marijuana.
This fMRI fingerprint of the decision to smoke marijuana allowed researchers to distinguish smokers from non-smokers with 100 percent accuracy, suggesting that a personâs brain activates in a distinct pattern when making the decision to smoke marijuana.
The functions of these brain regions tell us a little little bit about the decision to smoke weed, too:
- The dorsal striatum is associated with calculating rewards and making decisions.
- The insula is associated with initiating actions based on a personâs physical state.
- The posterior parietal cortex helps integrate information from different areas of the brain to execute functions
- The anterior cingulate cortex is associated with motivation and goal-directed behaviors
- The posterior cingulate cortex, while not fully understood, is thought to either direct oneâs focus of attention or be associated with internally-directed cognition.
How Does An Angular Roughshark Get Its Name
This shark has triangles all over its body, and its name cannot compare to how unique and interesting this shark actually looks. It also has teeth-like scales all over its body, making it very rough.
Along with their great sense of sight, sharks also have an incredible sense of hearing. These two senses combined make them one of the most efficient predators on the planet.
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Where Is A Shark’s Brain Located
The brain is hollow in most places, perforated by irregular ventricles. These hollows are filled with cerebrospinal fluid, which assists in the chemical regulation of the brain. The shark’s sense of smell is particularly acute, and almost two-thirds of the brain is dedicated to this sensory perception.
Beside above, what does a shark’s brain look like? The complete brain of an adult, 16-foot White Shark is Y-shaped and from scent-detecting bulbs to brainstem measures about 2 feet long. In comparison, the brain of an adult human is composed of two, wrinkly hemispheres and is about the size of half a cabbage.
Subsequently, one may also ask, does a shark have a brain?
A SHARK’S BRAINSharks and rays have very large and complex brains. Little is known about these brains. Sharks’s brains to body mass ratio is higher than most other fish and is comparable to many other vertebrates, including some mammals. Brain size and complexity vary from shark species to species.
Do sharks have two brains?
Answer: The brain size of sharks is not the same in every shark species, some of them have a Y-shaped brain with two bulbs. The brain mass to body mass ratio in sharks is much lower than humans, but they have a good rate when compared with some mammals and birds.
What Do Sharks Do For Fun Shark Week Expert Jeff Kurr Answers 15 Questions
Its that time of summer againits time for Shark Week!
To preview Sundays start of Discovery Channels wildly popular annual marathon of toothy TV, we asked Shark Week filmmaker, Jeff Kurr, who has helped helm Shark Week every year since 1991 and produced more than 30 shark documentaries, to answer some of our biggest questions about the fascinating sea predators.
What do sharks do for fun? How are they as parents? How smart are they, really? And what should you doand not doif you find yourself face-to-fin with one? Kurr answers all of these pressing queries and more in our Q& A, below.
Why are sharks so fascinating to humans?A few of us love sharks because weve spent time in the water with them. Its thrilling and awe-inspiring to get close to these animals. But for many, the fascination with sharks is rooted in fear and fear is a powerful drug. For these people, the shark is a real-life monster and we are all addicted to monsters.
What do sharks do for fun? Can they even have fun, the way dolphins do?Ive actually seen sharks that like to be scratched on the belly and seemed to enjoy being touched by humans. Not sure if thats fun for them but they do seem to experience a wide range of emotions, like fear, anger, frustration, and curiosity.
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Beluga Moves To The Rhythm Of The Music
A charming piece of anecdotal evidence provides an additional clue to the cognitive abilities of a beluga whale.
A third report is that of a beluga whale that moved its head towards the music played outside its tank. According to neurobiologist Aniruddh Patel, dance, or the ability to perceive rhythms and synchronize body movements with what is heard. Itis the product of a complex set of processes. One that, until recently, was among the distinctive hallmarks of the exclusively human skills.
The act of dancing at a rhythm is surprisingly complex: it requires creating and responding to a model inside the head in relation to what is heard externally. Indicates the ability to predict and wait. It also indicates that belugas could be vocal learners, just like people. another indication of cognitive complexity.
There is still much we can learn from these whales. And these reports indicate the great cognitive capacity of their brains.
What Does A Persons Brain Look Like When Theyre High
Marijuana enthusiasts know that being under the influence will change your perception of self and the world around you. So even though regular users might not think itâs too bad of an idea to jump behind the wheel stoned or possibly light up on the road, this 2013 study published in the open-access journal PLOS One suggests that THC changes your perception and attention so much that it can be difficult or dangerous to drive.
The study shows the levels of brain activity in people who are performing a âvisuo-motor tracking taskâ that simulates the cognitive processing and visual recognition a person would use to drive.
There are a lot of studies that show the inner workings of the brain of a person who uses marijuana, but there arenât too many that actually show what it looks like while theyâre stoned.
In this case, people who smoked marijuana and attempted the exercise showed a decrease in blood flow to their anterior insula, dorsomedial thalamus, and striatum compared to people who smoked placebo weed.
Now if you recall, the insula is associated with initiating actions based on physical state, and the striatum is associated with reward and decision-making. The dorsomedial thalamus is involved with memory and cognition.
While high, you might not realize that your dog is eating your Fritos, or, more dangerously, maybe not react in time to see a pedestrian running in front of your car.
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Sharks Have No Predators
Ajemian: Humans are the biggest shark predator. Weve done a lot of damage to the shark population. Were starting to realize what we have done and were having some successes in reversing that trend. Aside from humans, sharks do have predators. Typically its the smaller species that are preyed on, but even the big ones start out small. A 20-foot white shark was not born at 20 feet. Early in life is when large sharks are most susceptible. So predators can include other sharks seals and sea lions will eat smaller sharks theres evidence of big groupers eating smaller sharks and orcas, theyre still the top dog out there.
We rate this FICTION. Sharks have plenty of predators. The biggest predator and the greatest threat to sharks is humans. Each year, tens of millions of sharks are killed for their fins. We are disrupting the ocean ecosystem by killing too many sharks.
Structure And Function Of The
White Shark Brain
The shark brain has long been impugned as being tiny, simple, and relatively unimportant. Superficial examinations of the brain of small, evolutionarily conservative sharks such as the Spiny Dogfish seemed to bear this out. Experiments severing the spinal cord of swimming dogfishes, so that the brain could no longer co-ordinate swimming movements, have demonstrated that these sharks can continue to swim for several hours although they no longer respond to changes in their swimming environment. Sharks were therefore dismissed as primitive, stupid automatons functioning almost exclusively on the basis of brutish instinct. By painting all sharks with the same biased brush, we have arrogantly denied their biological diversity and grossly underestimated their mental capabilities.
How the White Shark translates sensory input and its brain’s internal chemistry to behavioral output largely remains a mystery. But why sharks in general have such large complex brains is far less so. A large White Shark has a brain that may measure 18 to 24 inches from the olfactory organs to the brainstem and features a relatively large, complexly folded cerebrum. Yet a scaled-up goldfish or salmon could make do with a fraction the cerebral endowment of a White Shark. All of which begs the question: what does a Great White think with all that brain?
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If Youre Swimming Off Floridas Atlantic Coast Theres Probably Sharks Nearby
Ajemian: Theres a misconception that larger sharks are the only ones out there. Its a result of them getting all the press, but really its a much more diverse assemblage of sharks, most of which are harmless. Bigger animals are generally rare. The most common sharks are the smaller ones, like the Atlantic sharpnose or bonnethead, which is like a miniature hammerhead. We have lemon sharks, black tips and spinners. We can see along the coast tiger sharks, great hammerheads and nurse sharks, but theyre actually rarer than those other species. Smaller coastal species, they can reproduce relatively quicker than larger species. What people see is different than what is out there. These smaller animals pose almost no threat to people. Its just like swimming among the fishes. People dont worry about snapper or grouper, but in the end, theyre not all that different.
We rate this FACT. There are dozens of species of sharks off Floridas Atlantic Coast, but most are small and harmless to humans. And many arent too far from where you are swimming.
How Does A Shark Brain Work And What Does It Look Like
Sharks are intellectual creatures with complex brains. It remains a misconception that sharks are unintelligent, surviving purely off instinct and spending their lives in pursuit of a meal. Research that supported this idea was rudimentary and usually based on the small sharks to which scientists had access. With increased time, finances and resources available today, though, more is being discovered regarding the intellectual capacity of sharks.
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Sharks In The Irl Are Only Found Near Inlets
Ajemian: This is something were still studying. We have a lot of these animals with acoustic transmitters and we have listening stations up and down the coast, trying to get a better assessment. My hypothesis is you see higher densities near the inlets because most species need a significant amount of salt water to survive. One of my students is working on that now. We have seen rays and smaller sharks detected in the interior. A study done in Brevard County showed a tagged juvenile bullshark that was tracked for several days near the power plant outflows
We rate this FICTION. While sharks are more commonly to be found near inlets, they also can make their way into the deeper recesses of the lagoon, quite a way from any inlet. The power plant at Port St. John is roughly 20 miles from the locks at Port Canaveral, and about 50 miles south of Ponce Inlet.