Walk into an aquarium, observe fish swimming in the tanks, and wonder about the lives they might have in the ocean. Pacific bluefin tunas swim across the Pacific like spangles. These creatures can reach 9.8 feet in length and 990 pounds in weight, and as fast as 30 miles per hour for 10-20 seconds. They are primarily found in Northern Pacific, but some can also be found in tropical and coastal regions and in temperate water. Typically, their habitats are located from 0 to 600 feet below sea level, or even rarer, -1800 feet.
Spawning occurs from April to August depending on spawning locations. Bluefin tunas spawn in Philippine sea and the Sea of Japan. Migrating to southern hemisphere and East Pacific Ocean after maturity they leave footprints in Australia, New Zealand, Gulf of Papua and French Polynesia. However, on their way to these destinations of migration from their far-removed homes, this ocean-going species is facing several population issues. Consumed by predators, slain by humans, choked by pollution, improperly protected by organizations formed by human beings--these troubles have caused a 96% decline in their population. Nowadays, different organizations like Greenpeace and Blue Ocean Institute have already placed Pacific bluefin tunas in their red or yellow lists, indicating the problem with this species’ status, furthermore, suggesting that people should not have done such intolerable decimation.
Manx shearwater is another variety of migratory animal that migrates more than 10,000 km to America, utilizing warm waters off southern Brazil and Argentina shore for food. . These long-living birds glitter in the air for at least 55 years. Born in Isle of Man, a manx shearwater can probably cover over 1,000,000 km, almost 24 times longer than the earth’s equator on migration alone. For example, a bird tagged in 1957 was calculated to have flown over 800,000 km during its 50-year-life.
But how do birds understand migration? Basically, migration evolves when birds that fly to another region produce more offsprings than that do not. The evolution of migration happens when a...