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As would be surprising, it turns out that mice have longer sperm than do elephants. In the animal world, if multiple males mate with the same female, a longer sperm would prove to be advantageous in fertilizing the female's egg. When it comes to fertilizing eggs, the two things that help are the length of the sperm and the quantity of sperm in the ejaculate. For smaller animals, the more important factor is the length of the sperm, as there is a higher possibility that multiple sperm will reach the egg. This higher probability of more sperm hitting the egg is due to the small anatomy of such small animals. So, when the sperm of small animals has to compete against other sperm, the one with the longer tail tends to fertilize the egg. Conversely, larger animals tend to have smaller sperm because of the longer distance the sperm has to travel to the egg. So, instead of making small amounts of sperm that have long tails, elephants make large amounts of sperm with short tails, as the real competition of fertilizing an egg in large animals is getting to the egg itself. This is why a whale's sperm is almost a thousand times shorter than that of a fly. I find this article of particular interest because it deals with the development of animals through sexual reproduction. The finding is largely linked with the idea of evolution, as animals with a sperm type that betters suits their anatomy have evolved to be that way. Certain organisms of a species may not reproduce because of their bad type of sperm, while other organisms of a certain species may because of their sperm that is best suited to out-compete other sperm. Therefore, the organism with the more advanced sperm will pass on the trait of having that type of sperm. http://www.sciencedaily.com/releases/2015/11/151118071404.htm
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A glacier in northeast Greenland is melting and has the potential to raise ocean levels by 18 inches. The glacier is named Zachariae Isstrom and is losing mass at a rate of 5 billion tons per year. The glacier is now breaking up and calving in ways that will increase the levels of the ocean. Data from aerial surveys and satellite observations are collected for the researchers. Both the bottom and top of the glacier are being melted away, with the top being melted by warming air and the bottom being melted away by warm water currents. Zachariae Isstrom neighbors another glacier, Nioghalvfjerdsfjorden, that is also melting, but at a slower rate.These glaciers make up 12 percent of the Greenland ice sheet and would raise the ocean level by 39 inches if they both melted. This issue is particularly important because the melting glaciers of Greenland are indicators of the warming we are causing to our planet. With the loss of our glaciers, an ocean level rise will increase and cause there to be a loss of coastline. People along the coast would and have to move, so, potentially, millions of people would have to move further inland. Besides the ocean level rise, the gradual warming of the planet can lead to climate changes that we do not yet know will result in. http://www.sciencedaily.com/releases/2015/11/151112150438.htm |
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April 2016
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