In the U.S., autumn can be an enjoyable season, with its comfortable weather and festive, bright orange pumpkins aplenty. But for animals that prefer warmer climates, cooler temperatures mean it’s time to move on to their seasonal homes!
Most of us have seen birds flying to their winter abodes, but there’s a lot of action happening under the sea, too. Many underwater residents also migrate, some due to seasonal temperature changes, others to take advantage of breeding opportunities. In fact, some ocean dwellers travel thousands of miles to meet their ideal mate or to locate the warmest sand for nesting. Here are some hard-working animals that really put forth 110% to succeed in their migration endeavors.
North Pacific Grey Whale
Among mammals, the North Pacific Grey Whale holds the record for the longest migration. At a confirmed 12,400 miles round trip, its route is the longest of any marine creature migration. Their journey starts in the Sea of Cortez, Mexico and ends in the Bering and Chukchi Seas. Their migration provides viewing opportunities both on and off shore in the US, Canada, and Mexico.
Once in colder seas, the opportunistic Grey Whales plow through the bottom mud and strain it through flexible baleen plates, eating tiny, shrimp-like creatures and tube worms. The whales fatten up each summer in preparation for the return journey south.
Orca
Another mammal with a considerable migration is the Orca. Unlike the usual motivations of food or mating, some Orca groups off the coasts of Antarctica travel 6,200 miles to the tropics to shed their outer layer of skin in the safety of warmer waters. One satellite tracking study has shown that Orca in the Canadian Arctic also undertake long-distance movement, likely to avoid heavy ice formations in the winter.
Leatherback Turtle
Leatherback sea turtles are among the most highly migratory animals on earth. Traveling between foraging grounds in search of jellyfish, the turtles can go as far as 10,000 miles or more each year.
Instead of the usual north-south migrations, the Leatherback sea turtle in the Pacific travels east to west. Using a tracking device, a confirmed trip of 12,744 miles has been recorded for a female migrating from Indonesia to Oregon… to lay her eggs in the sand!
Most sea turtles migrate between foraging and nesting grounds, and seasonally to warmer waters. With satellite telemetry, scientists can track the movements of sea turtles between areas and even across entire oceans.
The Leatherback has a light pink spot on the top of its head directly above its brain. It is thought that this allows light to reach the pineal gland, which may be used for migration. The pineal gland is an endocrine gland found in vertebrates, which affects wake/sleep patterns and functions to signal day length.
Northern Elephant Seal
Following roughly the same route as the Grey Whale, the Northern Elephant Seal racks up an estimated 13,000 miles. Keep in mind, though, that this marine creature takes on a double migration- traveling twice a year- once to give birth and mate, and another time to shed their outer skin and fur in a process called molting. They have a complex scheduling system with different age groups and sexes utilizing beach space sequentially. Space can be a limiting resource for this animal as their population is approximately 150,000.
Blue Marlin
The Blue Marlin is a highly migratory species, with individuals migrating across entire ocean basins and even between oceans. That’s quite a distance to swim, just to stay warm!
Less is known about fish migrations than other sea life, but a tagged Blue Marlin has been recorded as migrating 9,254 miles from the Atlantic to the Indian Ocean. Further research may discover longer journeys by this or other ocean fish.
Hammerhead Shark
Hammerheads exhibit philopatric behavior, meaning that they make return migrations after departing a particular area in search of mates or food. Additionally, they reside in specific locations and they show site fidelity in returning to the same areas repeatedly even over a number of years.
A recent study on Hammerhead migration was led by scientists from the University of Miami’s Rosenstiel School of Marine and Atmospheric Science (RSMAS). Using satellite tag technology, researchers were able to track a Hammerhead for 62 days and discovered its lengthy 745-mile journey from the coast of South Florida to the middle of the Atlantic off the coast of New Jersey.
Studies on Hammerhead migration provide vital information on how these endangered animals are affected by overfishing and environmental issues. Dr. Tristan Guttridge, who led a study at the Bimini Biological Research Station, in the Bahamas, explains why this is so vital: "Knowing when the animals are likely to be in certain places will be critical in developing effective management strategies" he said. "For example, our data could be used to create so-called 'time-area closures', where certain areas are closed to particular activities, like fishing, at different times. The aim would be to reduce harmful interactions with the sharks."
Have you observed a sea life migration? Share your experience below!
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