10 Facts About Great White Sharks
Shark videos 11 years ago 2,467,183 views
Remarkably little is known about great white sharks, but they are similar to humans in a lot of ways - they give birth to live young, maintain a higher body temperature than their surroundings and they are apex predators. There are also many misconceptions about these sharks: people think they don't get cancer and that they reside mainly in shallow waters near beaches. In this video I summarize some of the most interesting things I learned about sharks on my cage diving adventure. Special thanks to Rodney Fox Shark Expeditions for making this trip possible: http://bit.ly/rodneyfox Thanks also to Tourism South Australia for facilitating the trip: http://bit.ly/1aq9MgV Chris Cassella or C² as he is known after this trip was a shark spotter extraordinaire. He also took some of the best shark footage in this video. It was his idea to go on this expedition, which was definitely a once in a lifetime experience, so I am in his debt. Chris, I look forward to going on more great adventures with you. Check out Chris's facebook page ScienceAlert http://on.fb.me/18nhyLp
JK!
10. comment for 10 Facts About Great White Sharks
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30. comment for 10 Facts About Great White Sharks
I found your channel today after it was recommended today by several friends of mine. I binged watched your "new here try these vids" up until here and I love how you communicate science. However I would consider this video a black spot on your vest. Why? Because you're with a shark tour, in (what appears to me) relative proximity to the coast. Where you say sharks don't live. Where they shouldn't live. Where People live and bathe. And you're on a Shark/Tourism trip, where Sharks get fed. While in Proximity to People. To ships. To swimmers/Divers (even if in a cage). I haven't seen one yet, but I'm pretty sure you've got a vid about Pavlov?
Australia is infamous with shark fans about shark attacks, shark hunts and shark feeding, and all of this ties together for some part.
For those uninformed: Feeding sharks attracts more sharks. It teaches them that People=Food (not are, but get associated with). So they will search out people. They will stay closer to the coast. This is a problem. And with this video, you are further propagating this behaviour and also maybe spreading the will to do something similar with other people. For a channel of this format and a person of your intelligence, I am deeply disappointed by this.
True, fair enough. :/
yes...huuuuge problem..
Also sharks pose practically no danger to humans. Each year, only an average of one person dies from a shark attack in the US. In contrast, nearly 24,000 people are killed each year world wide by lightning.
50. comment for 10 Facts About Great White Sharks
Ha, fag!
She doesn't anymore, now she's taking her meds.
So I'm not sure if such a statement that you made earlier is logically coherent or even consistent with such a philosophical framework. (but that doesn't mean that I am saying we should kill all the sharks cause we can- I am not. It's just a thought experiment)
Wow.
Whenever I think I've seen the stupidest youtube comment, a new contender arises.
If you think you don't "deserve" to live then feel free to kill yourself.
Also thats the number that google gives when you search "How many sharks do humans kill each year?"
Well you don't swim with the sharks in an aquarium.
The sharks could be as malevolent as it gets, they simply have no way of hurting any humans.
+FRENCHshark diver
My creepometer is EXPLODING!!!
- Derek Caulfield
O YA, HAPPY SHARK WEEK EVREBODEH!!!!!!!!!!!!1!!!
Please don't support shark tourism :(
In this video you mentioned how the heat of the muscles in the shark transfers to the internal organs. But I want to know more about it in general.
Many if not most chemical reactions are exothermal, ie they give off heat to the environment around the reaction.
This also applies to the biological (organic chemical) reaction when ATP is changed to ADP. This is the main energy source in our cells, thus ultimately for most of our bodies.
This comes from the digested food, yes. But that's like saying a tree's leaves comes from the seed planted.
Although we require (comparatively) huge amounts of energy to keep our bodies going we can't apply it all at once.
That would simply kill our bodies.
Rather we need a tiny amount of applicable chemical energy in each and every bodily function in our cells. And thats where (mostly) the ATP-> ADP reaction cycle comes in.
Although many steps in that cycle actually require energy input to be performed that energy input is powered by the energy from previous steps.
Plus always a tiny (or even a substantial) lost amount of heat.
Which again powers the reaction speed of further steps.
A basic chemical premise is: the greater the heat the quicker the reaction speed.
All of this adds up to heat being lost to the environment, in this case not really 'lost' but used to heat up a body that would otherwise be too cold.
That's where the difference between warm-bodied and warm-blooded creatures comes in which Derek hinted at in the video.
The problem with biological systems is that we are made up of more than mere chemical reactions. Our bodies are in a fragile balance of keeping the heat up for greater efficiency in chemical reactions vs. the problems of keeping our proteins from denaturating from overheating.
Proteins are three-dimensionanlly folded molecules that most often can only fulfil their function correctly if they retain their three-dimensional structure and folding (laymen's terms here).
Once this folding unravels due to too much heat the protein stops working even if on a purely chemical basis it still remains the same molecule. But structurally it is something different and it thus fails to do its job in the body.
Warm-bodied creatures use active muscle control to heat their muscle groups which then transfers heat via conduction along the blood path to other areas of the body.
But this is not regulated by a sophisticated control system such as in warm-blooded creatures (btw: not really the scientific term). Once it reaches outer areas of the body exposed to the environment it tends to loose heat quickly. Heat distribution also occurs in a gradient from hot in muscle groups to significantly colder in the outer tissue layers.
That's also the reason why most such creatures can only sustain short bursts of high activity because their blood and temperature regulation systems are not able to cope with the heat build up in their muscles (ie a loooot of protein in muscles).
If the activity goes too high the heat from the muscle activity could damage the proteins. To prevent that evolution makes high activity only short-lived.
Warm-blooded creatures on the other hand try to regulate the body temperature within the body as equaly as possible - as long as this does not endanger the survival of the ultimate organs: heart, lungs, and brain. Once these are secured the regulatory system "goes down the list" of other less valuable organs until it achieves total heat distribution.
A fatty layer of tissue helps insulate against cold, and sweat glands help keep us cool in high heat. That's why fat people (like me, hehe) rarely feel cold, and skinny people tend towards feeling cold a lot more often. But that also means fat people sweat a lot more in our regulated homes or during hot weather than skinny people.
In hot weather people tend to get flushed because the body opens the upper tissue layers for the blood to get closer to the surface where the sweat glands are. Sweat evaporating is surprisingly effective at cooling us off. But obviously not as effective as jumping into cold water (water being a temperature conductor that is 25 times more effective than air, even with sweat evaporating on our skins).
In cases where the surrounding temperature is lower than our body temperature the body tries to preserve heat by limiting blood flow to upper tissue layers. That's the reason why first our skin feels colder, then our toes and fingers start to cramp when the body 'decides' they are loosing too much heat and restricts blood flow to them.
In cases of (for example) extreme hypothermia the circulatory blood system actually shuts off blood flow to extremities to conserve heat for the three major life-supporting organs, thus maybe extending the survival of the individual but at the cost of loosing extremities (fingers/toes first, then hands/feet, at last arms/legs). This could result in the loss even of other organs not necessary for the immediate survival of the individual.
Our regulatory system seems to have something similar to a list of triage organs which it would rather loose before others.
Not that this is a conscious decission, rather it evolved that way.
The last organ to loose a stable temperature in humans usually is the brain.
That's a reason why the human brain rarely gets warmer than 36.5° or 37° C. Even during high fevers or a heat wave. The body throws EVERYTHING in it's arsenal at the brain being kept from overheating or loosing too much heat. Our brain tissue is VERY sensitive to heat changes. Thus the body reactions include shutting down muscle activity (which generates more heat) to prevent brain tissue damage.
The major cause of heat stroke: a failure of the body to cool the brain to a lower temperature than ambient (if it's above our body temperature). Thus the unconsious controls knocks out the conscious stupdity, er, uhm, intelligence (that is: our self-awareness) that keeps pushing the body toward more activity when it already is overheating.
For an interesting side note on this...
Please check out the localised effects of older mobile phones actually heating the brain tissue where they were held close to the head. In many cases it was found that such older mobile devices held close to the head increased the localized tissue temperature by 1° to 1.5° C above the remaining tissue.
This seemed good news to the phone companies.
What negative effects could a mere 1° to 1.5°C have on the brain, right?
So the phone companies were all in the green, right?
Well, no.
Such an increase in brain tissue temperature usually occurs only during an extremely high fever in adults (ie a fever of 40.7° C or above) or a rather severe case of heat stroke and is the probable cause of fever hallucinations. As it occured quite far from our brain's temperature detecting structures AND it was localized it also was not rectified quickly.
What effect this has/had on the impacted brain tissue has not been studied sufficiently. But I dare to believe it probably did not improve the brain tissue.
I don't know about current mobile/smart phones but as they are usually not held close to the head when you use them their effects should be virtually nil.
Distances of more than a few centimeters away from the head effectively negate the induction heating effect of the wave lengths used to transmit information via phones.
So no reason to get all hyped up about phones cooking our brains.
But keep an open and inquisitve mind about such things. It helps you keep cool a lot longer ;)
But don't forget about the Rambuts!
Amoebas are protists, not an animal species.
100. comment for 10 Facts About Great White Sharks
We should actually kill all hostile animals untill they fear humans so much that playing dead is the preferred tactical choice when they are anywhere near a human being.
How rude, sharks also have lives you know..... you should be ashamed of yourself and now look great white sharks are ENDANGERED now.....be ashamed person!
Sherks, err mer gerd.
And FYI, we don't have sharks here in the UK, the water is too cold for them.
Have evidence that you are likely to see one
See one
He was simply stating that the number of deaths alone can not be used as an indication of the creatures fatality.
You must remember that significantly more people live in land than by the sea (Purely because the area of a country is going to be bigger than it's perimeter) and then very few of those on the shoreline live somewhere that sharks even inhabit.
Instead think about the percentage of people that encounter sharks and survive compared to the percentage of people that encounter cows and survive...
Thanks
Bonus fun fact. dogs in America kill more people per year than sharks do worldwide.
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Baby sharks are called 'pups'. Shark pups are born 4 feet long, and closely resemble a regular pup in no way whatsoever.
When a shark takes a bite, its eyes roll back into its head, making it momentarily blind. You try it. Now stop trying it.
Sharks do not only hang out in the shallow waters of beaches. They have also been known to attend parties with whales and porpoises. But not Mr Dolphin, because he's an asshole.