Youtor
rockclimbing goby
>> YOUR LINK HERE: ___ http://youtube.com/watch?v=Enx1rQIUkdk
GAIAPRESS continues to shed new light on the wonders of nature, including theories that used to be considered unscientific or have long been ignored, in order to gain a new perspective on science. • GAIAPRESS：http://www.gaiapress.com/en/ • Wonder Channel：http://www.gaiapress.com/en/article-f... • • Rock-climbing goby swim against strong currents and ascend the slippery, overhanging rocks of high waterfalls using mouth and pelvic suckers. • While some other fish species are known for their waterfall-climbing feats, none of them jump onto and over dry rocks like the rock-climbing goby. • What is it that drives rock-climbing goby to fight their way upstream over waterfalls and dry rocks? • Rock-climbing goby is a species of goby that lives in fresh water and has a life history very similar to sweetfish. • After laying eggs downstream, the young fish hatch and make a straight line for the ocean where they spend winter. • The ecology of these young fish living out at sea is not yet fully understood. • It is assumed that they feed off animal plankton around sand spits at the river mouth. • In spring, these goby form schools in estuaries and head upstream in groups, only eating algae once they enter the river system. • Starting out in schools of small fish, rock-climbing goby gradually begin to dominate single rocks and mark out their territory as they grow in size. • It's not difficult to imagine that fish able to monopolize the algae supply will grow larger and head further upstream where there is less competition. • In this respect, rock-climbing goby are extremely similar to sweetfish. • But, there are several critical differences between the two species. • Sweetfish are annual fish that only live for one year. • After heading upstream in search of algae, they go back downstream to lay their eggs in Autumn, unlike rock-climbing goby that breed in early summer. • Rock-climbing goby are thought to have a lifespan of 5 to 6 years. • After the long winter, they head back to the same area to lay eggs around the same time young fish head upstream. • Rock-climbing goby are destined to head back downstream after fighting their way against the current and over high waterfalls. • But, we still don't know when exactly it is that this takes place. • Some species of rhinogobius, a member of the goby family, are also known for waterfall climbing. • Rhinogobius is still the subject of classification, but it is believed that waterfall-climbing species such as the rhinogobius flumineus most likely lay eggs upstream where there are fewer fish in order to reduce the risk of their eggs being eaten. • There is no advantage for rock-climbing goby to lay eggs in this way, and they make the arduous journey upstream and over waterfalls later than sweetfish and rhinogobius flumineus. • It would seem that rock-climbing goby use their sense of smell to detect algae upstream, or have a lateral line with which they detect minute increases in water temperature that trigger their exodus upstream. Unfortunately, neither theory has yet been proven. • Algae in upstream areas rely on rises in water temperature and extended sunlight to grow. • It would therefore be dangerous to venture upstream should the river dry up, exposing this algae. • Sweetfish and rhinogobius are believed to head upstream early to preserve the species, or to grow large and gain an advantage during egg laying. • For reasons largely unknown, rock-climbing goby mysteriously lay their eggs at a different time and appear to confirm algae growth before making their way upstream. • Rock-climbing goby are widespread on the Pacific side of Japan south of the Kanto region. • While there's no accepted theory as to why they inhabit certain rivers and not others located nearby, many of these rivers have well-developed sand spits at the river mouth. • In the case of the well-researched sweetfish sharing a similar life history, sand spits are not regarded as having any bearing on their journey upstream. • A proper understanding of the life history and sensor mechanism of rock-climbing goby may very well serve to overturn such theories. • Humans do not have such refined sensors with which to measure the natural world. • However, humankind posses the power of analysis, one that goes beyond our natural limitations. • The protection of this diverse and beautiful earth through the analysis of nature is a mission that has been entrusted to humankind.
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