Presentazione sul tema: "Animali che migrano On the move"— Transcript della presentazione:
1Animali che migrano On the move Massive animal migrations are among nature's most inspiring events. Whether by wing, fin or hoof, the distance some creatures travel in search of a new habitat is paralleled only by what they endure to survive.Migrations also play a vital role in our natural ecosystems — they are the veins and arteries of Mother Earth — and they are a reminder that the world's habitats are interconnected. Here's our list of the planet's greatest migrations. (Text: Bryan Nelson)
2Le tartarughe marine Sea turtles These charismatic ocean wanderers make incredible migrations in the open sea.Some leatherback turtles have been recorded traveling across the Pacific Ocean between Indonesia and the U.S., an incredible distance of more than 12,000 miles in 647 days. One of their most impressive feats is the ability to navigate back the beach where they were born to spawn.
4Le meduseZooplanktonZooplankton are the countless numbers of organisms that float in the water column of the world's oceans and seas and includes organisms as diverse as jellyfish, krill and juvenile fish.Their migration is different because it moves up and down through the ocean's depths rather than traversing a landscape (although they can do this, too!). Known as vertical migration, the movement of zooplankton rivals the seasonal migration of more famous migratory species such as caribou or Arctic tern.Despite their tiny size, some zooplankton swarms swim a vertical distance of 3,000 feet nearly every day in the continual search for food.
5Le balene Baleen whales While many of the world's species of marine mammals migrate, none go the distance like giant baleen whales.The gray whale (which travels as far as 14,000 miles round trip annually) and the humpback whale (which travels as far as 16,000 miles round trip annually) migrate a greater distance than any other mammal on Earth.Each species travels to warmer tropical waters during the winter months to mate and give birth. Then they swim to the rich colder waters of the Arctic or Antarctic to feed for the summer.
6La libellula Dragonflies Dragonflies are capable of long-distance migrations, but until recently, scientists had no idea how far they traveled. In 2009, scientists discovered a 14,000- to 18,000-kilometer dragonfly migration route that spanned from India to the Maldives, the Seychelles, Mozambique, Uganda and back again.Incredibly, the epic migration spans four generations of dragonflies, with each generation playing its part in the journey much like a relay race. It is easily the longest insect migration ever discovered. The dragonflies appear to follow the rains, from the monsoon season in India to the rainy season in eastern and southern Africa.
7Gli uccelliBirdsAbout 1,800 of the world's bird species are migratory. Some of these journeys are among the longest in the world.The tiny Arctic tern (pictured here) undertakes nature's longest migration, spanning as many as 44,000 miles annually as it zigzags the distance between the Arctic and Antarctic. (Sooty shearwaters deserve an honorable mention for making a similar journey.) Seabirds like the albatross spend more of their lives flying than they do at rest, and bar-tailed godwits undertake the longest non-stop flight of any bird, between New Zealand and China.Penguins also migrate, and they deserve credit for making their incredible journey through the ocean, rather than through the air.
9La farfalla monarca Monarch butterflies The annual monarch butterfly migration might be the most colorful migration in the natural world.Outdistanced only by dragonflies among insects, the monarch migration spans 7,000 kilometers (about about 4,349 miles) includes three to four generations, and occasionally crosses the Atlantic Ocean. It is a spectacular thing to witness.Populations of the monarchs can be found in Australia and New Zealand, where they are referred to as wanderer butterflies.
10I pipistrelliBatsAlthough only a few bat species are migratory, the ones that travel seasonally do so in spectacular fashion.In fact, the world's largest mammal migration is the annual journey of Zambia's straw-colored fruit bats. An astounding 8 million bats blanket the air during the migration, as they travel to feed on their favorite delicacy, the musuku fruit.
11Gli gnuWildebeestPerhaps the most famous animal migration is the journey of Africa's wildebeest herds, which travel annually by the millions in search of greener pastures.The wildebeest do not travel alone. As many as 200,000 zebra and 500,000 gazelles also make the journey, followed by some of the savanna's top predators. The migration is one of nature's grandest spectacles, as the herds cross crocodile-infested rivers while lions prowl in the tall grass nearby.Africa's vast savanna could not exist without the migration, and maintaining these habitat corridors is essential to the survival of this area and its creatures.
12I carabuCaribouNorth America's caribou populations migrate the furthest of any terrestrial mammal, a journey that can span more than 3,000 miles annually.Herds of the migrating animals can grow to impressive numbers — as many as half a million individuals — rivaled only by Africa's great wildebeest migrations. During the winter, caribou travel to forested areas for easier foraging, and they migrate in the summer to superior calving grounds.
13Il salmoneSalmonOne of nature's most impressive migratory animals is the salmon. They are impressive for their ability to traverse both seawater and freshwater during their journey.Salmon are capable of traveling hundreds of miles inland via rivers and waterways, and will even ascend thousands of feet up mountain streams to return to the waters where they were born.
14I rospi di Christmas Island, Australia Christmas Island red crabsOne of the most incredible migrations is the seasonal movement of the red crab across Australia's Christmas Island.More than 120 million red crabs call this remote island home, and every year they transform the island into a vast moving red carpet as they move en masse to the ocean to lay their eggs.During periods of peak migration, Christmas Island's roads often must be closed as the crabs blanket the landscape. Scientists have recently discovered that hormonal changes cue the crabs to undertake their arduous journey.Granchi rossi
15I squali anche chiamati pescecani Sharks Many shark species travel thousands of miles through open water every year, scouring the ocean for food.The great white shark is a long-distance traveler, with some making the journey across the Indian Ocean, between South Africa and Australia and back again, over the course of a year.The larger, gentler whale shark is another known migrant, though its migratory patterns are not well-understood.anche chiamati pescecani
16Il tonnoTunaTuna are among the ocean's fastest swimming migratory fish. At least one tuna has been recorded making a 25,000-mile journey (three Pacific Ocean crossings over the period of just 20 months) between the U.S. and Japan.The amazing migration was recorded by the 10-year Census of Marine Life, an undertaking that includes experts from 73 countries.
18Il pinnipeda Sigilli…foche…trichechi Pinnipeds Pinnipeds such a seals, sea lions and walruses also are known for making incredible sea journeys.Fur seals are known to swim the equivalent of a fourth of the way around the world every year. Elephant seals have been recorded making a 20,000-kilometer migration every year, and they also dive deeper than any other seal. Walruses have a migratory route through icy Arctic waters, a journey that has been a mystery to scientists until recently.Sigilli…foche…trichechi