Navigation is the ability for an organism to travel to a relatively precise target, generally at a considerable distance, without the need for familiar landmarks. It is an extraordinary feat requiring a variety of senses, techniques, and adaptions to allow for successful navigation.
Humans and Sight
For humans, sight is the most commonly used sense to navigate. Tracing back a thousand years ago to traditional Polynesian cultures, people have been using the stars, specifically fixed stars, for tracking and to stay en route towards their destination. Nowadays, we have technological advances that aid us in navigation, like Google Maps, satellites, and compasses, but celestial bodies remain a constant and dependable asset. In addition to sight, different animal species have evolved specific senses to assist them in the open ocean.
Photo: http://www.hokulea.com/education-at-sea/polynesian-navigation/the-star-compass/
Dolphins and Hearing
Some animals, such as dolphins, utilize their sense of hearing through a process called echolocation to navigate through the open ocean during times of low visibility. These animals produce high-frequency sound waves that echo back with information such as the direction they are traveling and the location of objects around them.
Photo: http://www.dolphinspotter.karoo.net/factecho.htm
Photo: https://aqua.org/Experience/Animal-Index/atlantic-bottlenose-dolphin
Crabs and Taste
Crabs, who often live in dark and murky areas, need to be able to navigate to food sources. Crabs use chemoreceptors found on thin, short hairs of their inner antenna, call aesthetascs, which allow them to smell chemicals in the water released by their prey. They not only have a well-developed sense of smell, but have the ability to taste biomolecules in the water using specialized hairs on their mouthparts, pincers, and feet to detect prey. Their acute senses are so crucial to survival, that the majority of their brains are detected to processing scents and tastes!
Small hair-like appendages of the Green Crab that aid in prey detection by taste.
Photo: https://wsg.washington.edu/crabteam/about/newsletter/2018-1/
Seabirds and Scent
For some seabirds like the Arctic Tern, the Wandering Albatross, or the Sooty Shearwater, navigation is no joke! Traveling thousands of miles for up to seven years at a time over a featureless blue ocean is quite a feat, requiring some fine-tuned navigational techniques. Studies have shown that many migratory birds use celestial navigation to determine North and Southward orientation, just like humans! But certain hypothesizes suggest that seabirds also use their sense of smell to create scent maps. In a study where birds had their sense of smell blocked, the test group was less likely to find food sources and their nesting grounds, suggesting that olfactory navigation is a technique adopted by many seabirds!
The Wandering Albatross has been observed to spend anywhere between 5-7 years at a given time at sea, making them expert navigators.
Photo: https://www.hbw.com/ibc/photo/wandering-albatross-diomedea-exulans/old-adult-male-flight-dorsal-view
The Arctic Tern has the longest migration of any animal, traveling from Greenland go Antarctic in a zig-zag route, resulting in over 40,000 miles traveled every year!
Photo: https://www.npolar.no/en/species/arctic-tern/
Fish and Touch
The lateral line system is an extensive network of canals and sensory receptors that can detect disturbances in the water. The majority of fish species have this lateral line that assists in navigation by sensing pressure changes and providing spatial awareness to avoid underwater obstacles. Some fish are able to use the lateral line as a type of sonar to feel the movement of water reflect off objects around it, which is especially useful in low visibility areas, such as the deep sea.
The lateral line consists of hundreds of superficial neuromasts, or sensory structures of cilia. Many of these neuromasts are embedded in lateral line canals open to their environment through pores that allows them to detect water movements.
Photo: https://www.trails.com/facts_8518_functions-lateral-line-fish.html
Sea Turtles and Magnetoreception
Magnetoreception, the sixth navigational tool illustrated in the video, is an animal’s ability to detect the Earth’s magnetic field in order to determine North and Southward orientation. Many invertebrates like mollusks and insects, as well as vertebrates like birds and sharks, use this as a natural global positioning system when navigating long migration routes. One example, sea turtles, use magnetoreception as hatchlings when swimming out to the open ocean, and as adults when traveling towards specific feeding, mating, and nesting locations.
Magnetite is found in sea turtles as well as some bird and fish species. This iron mineral can tell animals their position on the globe as well as the direction they are heading. This explains why sea turtles can migrate all around the ocean and find themselves nesting on the same beach as their female ancestors.
Photo:https://www.sciencemag.org/news/2016/06/body-s-hidden-compass-what-it-and-how-does-it-work
Photo: https://webstockreview.net/image/field-clipart-campo/1087594.html
The open ocean can be a challenging place to navigate, but the animals that live there utilize their senses to the max in order to find food, avoid underwater obstacles, and be completely aware of their direction of travel.
Sources:
https://www.thoughtco.com/how-do-crabs-find-food-2291888
http://lohmannlab.web.unc.edu/magnetoreception/
https://www.cell.com/current-biology/pdf/S0960-9822(07)00819-6.pdf
https://www.wonderopolis.org/wonder/how-do-dolphins-use-echolocation
https://www.ncbi.nlm.nih.gov/pubmed/21392273
Written By: Alyssa Backman, Kyler Mose, and Leanne Murray
