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Shed light on mysterious jellyfish food

Atlantic Sea Nettle. Credit: Jessica Schaub

Jellyfish have a greedy appetite and are not considered the most selective eaters. Almost anything that gets caught in the tentacles gets caught in a gelatinous bag used to digest food.


This “take what’s coming” feeding strategy has clouded our understanding of what foods jellyfish survive and how they fit into the food network. However, a new study by the Marine Fisheries Research Institute (IOF) used two biochemical tools, stable isotopes and stable isotopes. fatty acid, Begin to uncover the secrets of feeding jellyfish.

Stable isotopes are naturally occurring isotopes of elements such as carbon and nitrogen that are present in specific proportions in all living tissues. Similarly, fatty acids, which perform some important physiological functions in the body, are produced in a unique composition by the plants at the base of the food network. Unique isotopic and fatty acid “signatures,” also known as “biomarkers,” are passed from prey to predators and can be used to track food network connections and illuminate the dietary composition of animals.

Isotope ratios and fatty acid concentrations change subtly in a predictable way as they cross the food network. However, these changes, called “calibration values,” can vary from organism to organism, and it is essential to know the organism-specific calibration values ​​in order to accurately use biomarkers to investigate the diet. ..

“In the past, jellyfish ecologists used generalized calibration values ​​for these biomarkers because they lacked jellyfish-specific biomarkers,” said the lead author of the study and a recent master’s degree. Jessica Shaub said. I will graduate from IOF. “This study tested how the isotope and fatty acid levels change and how quickly they are absorbed when the jellyfish digests the prey and incorporates the characteristics of the prey into the body.”

“The numbers we found were quite different, so it’s worth going back to the previous study of jellyfish that applied the general values. Applying our values ​​could give different results. Yes, “says Schaub.

In other words, jellyfish food can look quite different than expected, and new studies may show that some jellyfish occupy a completely different position in the food network.

Shed light on mysterious jellyfish food

Measurement of jellyfish. Credit: Jessica Schaub

Studies published in Journal of Experimental Marine Biology and EcologyWas a partnership between IOF researchers and the Vancouver Aquarium.

Vancouver Aquarium staff cultivated both jellyfish species and fed them with two unique crustacean diets. The large and ferocious Japanese Atlantic Sea Nettle was also given a small and common moon jellyfish.Researchers were waiting to see how long it would take a jellyfish to take up a jellyfish Stable isotope We calculated how much the fatty acids, fatty acids, and the two biomarkers changed.

“It sounds easy, but it’s not that easy. We’re getting the data and wondering what’s going on here,” Schaub said. “I was surprised by the moon jellyfish. I fed two crustaceans, krill and artemia, but they didn’t actually have krill in them. If it didn’t seem to be the case. ”I like to feed a single meal. They did not meet their nutritional needs or preferred live artemia over dead frozen krill. Aquariums have eaten these krill for a long time, so it’s good to be able to do it. To tell the aquarium that it may not be worth the investment in krill anymore. “

Studies have also found that jellyfish appear to “stretch” fatty acids. This means that jellyfish may be able to produce their own essential omega-3 and omega-6 fatty acids that are important for healthy body functioning. Most animals can’t make these fatty acids from scratch, but this was surprising because they need to be obtained from the diet. This phenomenon has been explained by several other organisms such as coral and sponges, but not by jellyfish.

The authors of the study hope that these findings will be a step towards a better understanding of the role these under-studied creatures play in marine ecosystems.

“Jellyfish have long been ignored in research and are often seen as more annoying than the organisms of interest,” said Dr. Brian Hunt, a professor at the IOF and co-author of the study. “But there is growing awareness that they can play an important role as both predators and prey.”

Schaub will take this basic research further when he begins his dissertation at the IOF in 2022. “I’m looking forward to what we can learn about jellyfish using the biomarkers developed in this study. I’m particularly interested in the role of jellyfish. As a keystone species that shapes marine ecosystems,” he said. ..

The author of the study was at the Vancouver Aquarium jellyfish Assisting them in experiments and Pacific Science Enterprise Center for fat assistance acid analysis.


Why do jellyfish still attract predators when they don’t contain calories?


For more information:
Jessica Schaub et al, experimentally derived estimates of stable isotope and fatty acid turnover and modification of potworm jellyfish, Journal of Experimental Marine Biology and Ecology (2021). DOI: 10.1016 / j.jembe.2021.151631

Quote: Https: //phys.org/news/2021-10-mysterious-jellyfish-diets.html Lights the Mysterious Jellyfish Meal (October 14, 2021) Obtained on October 14, 2021 Hit

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Shed light on mysterious jellyfish food

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