32
POPSAmazing Shark Pictures Off South African Coast "To see a perfectly streamlined great white slowly cruising in clear water with shafts of light bouncing off its back is like watching a sports car effortlessly cruise past you on the freeway. It is just one of those moments that makes you appreciate a beautiful creation."
31
POPSAnimal senses humans don't have You might think you're smart, but none of your senses rival the keenest abilities in the animal world. Animals see in the dark, sniff prey miles away, and detect electrical output from muscle twitches in hidden meals. Read on, so you don't become one of those meals.<<
18
POPSMass extinctions? Blame it on the ocean In the course of hundreds of millions of years the world's oceans have expanded and contracted in response to the shifting of the Earth's tectonic plates and to changes in climate. There were periods of the planet's history when vast areas of the continents were flooded by shallow seas such as the shark and mosasaur infested seaway that neatly split North America during the age of the dinosaurs. As those epicontinental seas drained, animals like mosasaurs and giant sharks went extinct, and conditions on the marine shelves where life exhibited its greatest diversity in the form of things like clams and snails changed as well.
18
POPSPictures inside the mouths of sharks at feeding time You don't want to be here. 'We tie fish scraps onto fishing lines (no hooks) and bait lemon sharks in as close as possible. 'When one opens its mouth to "snap" at the fish, I take the shot. These snaps literally last a fraction of a second, so timing is critical. 'Recently, the technique has been changed. These days, all surface shots of lemon sharks are done via "polecam", with cameras mounted at the end of long poles. 'This prevents any possible accident.' In October, Eric be travelling to Japan on an expedition to photograph sperm whales (assuming he is still alive).
13
POPSHow To Survive A Shark Attack If you're out diving and you see that big dark murky ominous shadow coming closer, if you don't have time to get out of the water, head for the bottom. Sharks attack from below and up, so get yourself flat to the ocean floor and wait for it to swim away. Stay calm, don't panic. Remember you have to totally over-exaggerate the size of the beast later, when you're at the pub, bragging about how you survived your ordeal. It's the custom. (All who have ever fished, will understand this rule. ;))
12
POPSThe end of Men? A surprising number of animals can reproduce without male involvement if there is no other option. Sharks and lizards have demonstrated this ability in captivity. It was previously believed that the process was impossible in mammals such as humans because male sperm cells and female egg cells undergo a process called imprinting. In imprinting, sections of each cell’s genome are silenced to allow the set of genes from the other parent to be expressed, so that when the egg and sperm cells combine, the genes in the resulting embryo are not competing with each other. It has now been discovered that it is possible to interrupt this process by deleting just two sections of genetic material on the genomes of female mice – animals very similar, for reproductive purposes, to humans.
11
POPSGreat White Sharks http://animals.nationalgeographic.com/animals/photos/great-white-sharks/eye-level-great-white.html
10
POPSConvergent evolution
The huge fossil teeth of megalodon had been known for centuries and were once believed to be the fossilized tongues of dragons. Agassiz, noting that great white shark teeth and the fossil megalodon teeth were both serrated, lumped megalodon into the same genus, Carcharodon, (from the Greek karcharos, meaning sharp or jagged, and odous, meaning tooth). Agassiz was not, however, making an evolutionary judgment. In 1835, a young Charles Darwin was just then visiting the Galapagos Islands. There would be no theory of evolutionary descent for nearly 25 years. In fact, the brilliant Agassiz, who later became a professor at Harvard and the leading figure of natural history in the United States, forever resisted Darwin’s revolutionary ideas. Rejecting biological evolution, Agassiz defined species as a “thought of God.” His classification scheme signified nothing about shark origins. But over the next century, the idea that great whites evolved from megalodon took hold. << more at the