Panther is actually a term used in many countries to characterize
a black color variant of any of diverse species of big cats such as the black
cougar, jaguars and leopards.
Hope
you have enjoyed this weeks short and sweet Friday facts segment!! Thank you for
stopping by. Would you like us to mention a fact in next week Friday
facts? Make sure to leave a comment
and come back for more articles!!
Greetings everyone, Carrying on with the theme of enhancing your knowledge on shark biology we bring to you answers to some pretty puzzling shark questions. Starting with...
On the 19th of July 2013 a Mako shark (seen below) was spotted in British waters for the first time in 42 years and in 2012 a great white was spotted 12 miles from Cornwall, how are they able to enter such cold water when sharks usually occupy warmer waters?
Well lets start of by saying that most bony fish (except for tuna) and most sharks are considered to be ectothermic meaning they are unable to warm themselves through their metabolism, this is the reason why many sharks have to remain in warmer waters. However, the exceptions to this rule are the mackeral sharks, these include your Mako sharks and your Great White Sharks and the common Thresher shark, all of these sharks are considered to be endothermic. But why? They owe this adaptation to a network of blood capillaries called the rete mirabile, with blood flowing in opposite directions that are able to act as a heat exchanger. In simple terms, heat is transferred to the blood that is flowing back into the body from the gills, whilst the blood that is flowing out now looses less heat to the surroundings. This remarkable adaptation allows for the temperature inside the body to be 5-14 degrees above the temperature of the surrounding water!! There are three retia areas that are known.
Swimming muscles
Brain
The intestines in particular the stomach
A sharks skeleton is made out of only cartilage, so if they lack bone marrow how does a shark make red blood cells?
This posed as a huge mystery to all scientists when they realized that a sharks skeleton is made out of cartilage, that was till they found that this job was performed by the spleen. In case it has slipped your mind what a mammals spleen does, a mammals spleen filters out old red blood cells, whereas the spleen in most sharks generates red blood cells. It is found near the reproductive organs. However not all sharks share this red blood cell generator, some species have a special structure called the Leydigs organ, in the species that this occurs in is is usually nestles along the top and bottom of the esophagus.
Is it true that sharks live cancer free?
No. Sharks are not a cancer free species, they are just very, very unlikely to have a tumor. It was found that of the large quantity of fish tumors held at the Smithsonian only 15 are from elasmobranchs (sharks and rays), and of which only two were malignant. Tumors is basically an uncontrolled cellular growth, and in order to support their very high metabolisms they secrete a hormone called angiogenin. Angiogenin causes nearby blood vessels to grow new branches surrounding the tumor thereby securing a transport system that bring by all the nutrient they need and removes all they waste as well. Now, sharks are unlikely to have tumors because they naturally produce a compound that has antagonistic effects of angiogenin. It was conveniently named angiogenin inhibitor, and does just what it says in the title, it inhibits in other words stops the tumor from gaining a nutrient supply, and with no waste removal the tumor begins to 'choke' on its own waste. Well this marks the end of Shark Week for us here on Biobunch we hope that you gained some new insights into shark behaviour anatomy and physiology, until next time guys this is... Biobunch over and out.
Not sure how you guys are feeling about this years shark week, but if we didn't make ourselves clear on the previous post about the Megaladon then let us just say that we are officially OUTRAGED!! We would like it to be noted that Discovery Channel and NatGeoWild have shamed the annual marvel that is shark week. Firstly, shark week is about raising awareness about sharks, creating a deeper understanding about this often misunderstood and misrepresented creature of the deep, informing the public that sharks are not hell bent determined on killing every single human being that ever enters the ocean. Secondly, why is it that every single documentary that is shown shows the sharks behaviour and then leaves it at that, why are they not going into the anatomy of the sharks the biology that drives these amazing animals to do what they do. Instead what we get is the following: When Sharks Attack, followed by When Sharks Attack and ended with When Sharks Attack. Moral to the story viewers, sharks are evil! Well that's the vibe we feel when we watch these documentaries tell us after watching these do you come away with an overpowering urge to HELP SAVE THE SHARKS?! No, well we don't blame you!.
This lead us to the post we are giving you today, a true dedication to why sharks are awesome! in the next two posts we will mind blow you with some awesome shark biology. Enjoy!
The Lateral Line System:
Ever wondered how sharks are able to pinpoint their prey with deadly accuracy, or how they are able to navigate there way across half the globe, well the simple answer would be their lateral line system. This system is made up of tactile sense organs that are able to detect movement and pressure changes in the surrounding water, in a few words it is able to detect water displacement.
The lateral line system is visible to the naked eye on sharks. They are seen as small skin perforations on the sharks cavity.
Each perforation seen on the shark contains a bunch of mechanorecptors (receptors that receive mechanical stimuli) also known as neuromasts. They lie embedded in mucus filled canals called the lateral line canal, the neuromasts are made up of sensory cells and support cell and as seen in the picture below they are encapsulated within a gelatinous dome, the tubule given the neuromasts direct contact with external stimuli. But how do they use this for prey detection? Well picture this, a seal is swimming thereby displacing the water surrounding it, these waves sweep across the sharks surface and the change in pressure is carried down the tubule and into the lateral line canal. This pressure change causes the gelatinous dome to bend, causing the neuromasts to bend also- thereby triggering an electrical change in the basal body (the individual cells in the neuromasts) the neurotransmitters pick this change up and the sensory nerve carries this to the brain where it is interpreted and the shark can either choose to move towards it or ignore it.
It doesn't stop there...:
Some of the neuromasts made up of mechansosensory receptors have become evolutionary modified to become electrorecpetors, this specialised system concentrated mainly around the snout of the shark is called the Ampullae of Lorenzini. With this the shark has enhanced its ability in detecting indirect touch, as they are now able to detect minute electrical potentials which are generated by muscular contractions. When humans swim for instance they give of a different electrical field compared to that of the surrounding water, which is then carried to the ampullae of lorenzini. It also explains how sharks are able to migrate their way across such large distances, because they are able to detect the earths electromagnetic field.
A diagram showing the structure of this system. Similar to that of the lateral line system, but is connected straight to the external environment.
Similar to that of the lateral line system you are able to see the perforations with your naked eye!
Well that rounds up today's post on how the Great White Shark uses two of its most interesting sense for prey detection!! For those of you who are craving more information on shark anatomy and can not wait for our awesome post tomorrow have no fear because below you will find the full documentary of INSIDE NATURES GIANTS: THE GREAT WHITE SHARK! now this is what we call shark week material! Tomorrow we shall be answering some pretty awesome questions on the physiology. Make sure you don't miss out on it!!
Greetings everybody, Enjoying shark week?! How did you find the opening of
shark week on Discovery Channel? We’re referring to the fake Megalodon
documentary! Disappointing “documentaries” are being aired on discovery channel
leaving many viewers including us speechless. A channel that was highly
respected as an educational channel has now become something like SyFy channel.
In complete agreement with Will Wheaton as to Discovery Channel owing its
viewers an apology.
''Sharks are
fascinating, and megalodon was an absolutely incredible creature!
Discovery had a chance to get its audience thinking about what the
oceans were like when megalodon roamed and hunted in them. It had a
chance to even show what could possibly happen if there were something
that large and predatory in the ocean today … but Discovery Channel did
not do that. In a cynical ploy for ratings, the network deliberately
lied to its audience and presented fiction as fact.Discovery Channel betrayed its audience."
Source.A
Megalodon adult shark could have grown over 60 feet and weighed as much as 100
tons which made it an apex predator.
Megalodon (Carcharodon Megalodon)
meaning big tooth in Greek is an extinct species of shark that wandered the seas
and oceans 28-1.5 million years ago. It was given its name as its teeth were
about 7 inches long whereas the biggest teeth of a great white shark are only
about three inches long.
Source. Megalodon's tooth (black) with two great white shark teeth (white)
Megalodon lunched on giant prehistoric whales paralyzing them by biting their fins or damaging delicate organs. Using computer
simulations a joint research team from Australia and the U.S determined
Megalodon’s biting power. Megalodon’s biting force was equal to 10.8 to 18.2
tons (by comparison the extant cousins the great white sharks chomp with about
1.8 tons force, a Tyrannosaurus Rex chomped with 3.1 ton and a lion with a
wimpy 600 pounds), thereby concluding that Megalodon had the most powerful bite
of any creature that ever lived.
The subject of Megalodon extinction still
remains under examination and over the years many possible causes for its downturn have been proposed such as
oceanic cooling and sea level drops, new competition and a decrease in food
supply leading to death by starvation.
However Michael Sorensen, executive producer of Shark Week said: "95% of the ocean unexplored, who really knows?”
What do you think? Do you think the monster still alive hidden in our unplumbed ocean?
We'll leave you with a less time consuming and more factual documentary than the one on discovery channel.
