 |
 |
|
|
| |
| |
| |
|
|
| Articles about Galapagos |
| Pirates of the Galapagos | | 2008-05-30 16:00:15 | | They may not have the same wacky wit as Johnny Depp’s Captain Jack Sparrow, but the pirates of the Galapagos had their share of adventures among the otherwise pristine islands. During the 1500s and 1600s – as Spain was busy collecting the wealth of the Incas and shipping it home – the pirates (or buccaneers, [...] | | By: Travel Stories & Travel Information - StorySui | | |
| | Galapagos sharks | | 2007-05-07 23:11:00 | | Galapagos sharks are so little studied because they are only found in remote places like the Islands they're named after, the only twist is, this is not the Galapagos Islands, but Midway Atoll.Midway Atoll is a Pacific atoll that lots of us are familiar with, but it's been pretty well off limits to all but government and military personnel for about the last sixty years. Just like you'd guess from its name, Midway Atoll is in the middle of the Pacific Ocean, half way between the US mainland and Japan. That geography makes it a strategic outpost.Because public access has been restricted since the war, Midways reefs have grown a healthy population of Galapagos sharks and now that Midway has opened up to tourism, more people are going to meet these sharks than ever before.The Galapagos belongs to a branch of the shark family called whalers. They mainly eat small fish and squid, but they are known to have killed at least one diver in the Virgin Islands.The Galapagos shark is a kind of unusual shark in that it has a very odd distribution. Where it is found around the oceanic islands in the Indian, Pacific and Atlantic but yet they are so scattered there is not a lot of information known about them.You can tell them from grey reef sharks quite easily because Galapagos have a ridge of skin running along the back between the first and the second dorsal fins. Galapagos also have less of a black line on the trailing edge of the tail fin.Galapagos sharks have excellent vision, and their other senses make them very alert to prey in light or darkness.Like most other sharks, their acute sense of smell means they can hone in on a scent from hundreds of yards away. Their snouts have pits filled with tiny sense organs called ampullae of Lorenzini. These can detect the tiny electrical field of nearby prey, helping them hunt for fish in the dark. They can even detect something like a stingray buried under the sand. That electrical sense works fine at short range, say abo | | By: NHNZ Images | | |
| | Body Size, Performance and Fitness in Galapagos Marine Iguanas | | 2007-01-16 06:12:48 | | Integrative and Comparative Biology 2003 43(3):376-386; doi:10.1093/icb/43.3.376Martin Wikelski and L. Michael RomeroComplex organismal traits such as body size are influenced by innumerable selective pressures, making the prediction of evolutionary trajectories for those traits difficult. A potentially powerful way to predict fitness in natural systems is to study the composite response of individuals in terms of performance measures, such as foraging or reproductive performance. Once key performance measures are identified in this top-down approach, we can determine the underlying physiological mechanisms and gain predictive power over long-term evolutionary processes. Here we use marine iguanas as a model system where body size differs by more than one order of magnitude between island populations. We identified foraging efficiency as the main performance measure that constrains body size. Mechanistically, foraging performance is determined by food pasture height and the thermal environment, influencing intake and digestion. Stress hormones may be a flexible way of influencing an individual's response to low-food situations that may be caused by high population density, famines, or anthropogenic disturbances like oil spills. Reproductive performance, on the other hand, increases with body size and is mediated by higher survival of larger hatchlings from larger females and increased mating success of larger males. Reproductive performance of males may be adjusted via plastic hormonal feedback mechanisms that allow individuals to assess their social rank annually within the current population size structure. When integrated, these data suggest that reproductive performance favors increased body size (influenced by reproductive hormones), with an overall limit imposed by foraging performance (influenced by stress hormones). Based on our mechanistic understanding of individual performances we predicted an evolutionary increase in maximum body size caused by global w | | By: Evolution Research - Main Blog | | |
|
|
| |
 |
|
| |
| |
|
 |
