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The underwater world of kelp forests is a dark and mysterious place filled with beautiful creatures. Some of them – sea otters – are among the most charismatic aquatic mammals. Recently published research from the University of California at Santa Cruz helps us examine the gap and understand how these creatures in search of well-being find food.
In the work, a sea otter named Selka worked with UCSC's Sarah McKay Strobel to demonstrate her ability to use her sensitive paws and whiskers to explore the world around her. Strobel's findings, documented in a published article Journal of Experimental Biology, show that Selka has proved much faster than humans to identify the world around her by touch – which could illustrate how important it is to touch aquatic mammals like sea otters .
Selka has a long history with the Monterey Bay Aquarium, where she is now a permanent resident after several attempts to liberate her in the wild at the beginning of her life. Between 2014 and 2016, she worked at the nearby Long Marine Lab with Strobel, her co-authors and a team of volunteers to help them understand the sensitivity of her paws and whiskers.
With the help of some seafood treats, the researchers gradually introduced a blindfold into Selka's eyes and she got acquainted with the other experimental equipment: a small cabinet on the side of the pool with openings of different sizes. She could reach her paw directly into the cabinet, without a headband, and learn to distinguish the feel of a board that had 0.08-inch grooves along it and other cards. with grooves of different sizes. She also learned to use her whiskers, blindfolded, to feel the difference.
Strobel says that Selka's cooperation and not pushing his limits was the key to the design of the experiment. In the end, she says, Selka "really liked to experience" for the stimuli (and snacks) that she provided, and even became very comfortable wearing blindfolded . It could have been very different, she says: "Imagine yourself in this situation. It can be scary that someone has blindfolded you and then asks you to do these complex tasks.
But in this case, after Selka became familiar with the conditions, it was time to conduct the actual experiment. "You have to have a very controlled environment," says Strobel. Previously, she attempted to observe the underwater tactile behavior of sea otters in the wild, but given the darkness of the marshy areas of the otters, the limited visual range of the cameras and other technical problems, " Even during the day, "she says," the water can be so cloudy that it looks almost like the night. "
Strobel's type of experiment with Selka reflects other experiments with aquatic mammals such as manatees and pinnipeds such as seals and sea lions. With Selka under the experimental conditions to which she was now accustomed, she distinguished the planks with different groove widths. One of these tips, however, still had a 0.08 groove, and when Selka identified this one by pressing it firmly for it to make a loud popping sound, she received a reward. The researchers found that Selka could detect a difference of about 0.04 inches. They were also surprised to learn how fast she could do it: she needed only 0.2 seconds with her paw and 0.4 seconds with her mustaches. Human volunteers who agreed to try the test took about 30 times longer to identify the difference with their fingers.
One of Selka's advantages was that she did not compare the two options: she would feel one, and if it was the 0.08-inch groove, she would squeeze it right away without feeling the other. to be compared. That means you remember what the targets are, "said Gordon Bauer, professor emeritus at New College of Florida. He was not involved in the current experience, although he did a similar job on manatees. Like manatees, he says, Selka has turned a forced choice between two objects into a "go / no-go" experience. She just remembered what she was looking for and identified it when she found it, without comparing it to other nearby objects to check.
In terms of time and sensitivity, Sea Otter's capabilities appear to be comparable to those of Pinnipeds and Manatees. "This is the first work that has been done on sea otters," he says, and provides more evidence of the important role whiskers play in the detection of aquatic mammals. Otters also add a new layer with their paws, which are lacking both manatees and pinnipeds.
For Bauer, the ability to quickly distinguish different objects to the touch is very much related to the memory of all these animals. In the case of Selka, says Strobel, and sea otters more generally, this memory is essential for finding food quickly in troubled waters. Sea otters only spend one to three minutes under water during a given dive, she says. During this time, they must reach the depths of foraging and find their sea urchins or other tasty foods. Being able to remember how things should feel can be a key part of that, she says.
This new study adds a dimension to the current understanding of sea otters. Although they have been studied extensively over the past 25 years, these studies have "focused on the life of sea otters on the surface of the water" says Mr Strobel. But since sea otters consume about 25% of their body weight a day and all the food has to be collected under water, scientists lacked much of the picture, she said. the food in the short intervals that they spent underwater. This research points to being a big one.
Thanks to Selka, environmental advocates who work with sea otters in Monterey Bay and elsewhere now know a little more about how their loads are seeing or feeling the world.
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