Sharks, Rays Have Few Options Than a Slow Lifestyle in Cold Waters, Study Says

A scientist at the Research Center for Integrative Evolutionary Science, The Graduate University for Advanced Studies (SOKENDAI), led the study about the cold environment's effects on massive sharks' lifestyles. Dr. Yuuki Y. Watanabe and his colleague learned that sharks and rays don't thrive in such an environment.

Sharks Have Slow Lifestyle Due to Cold Waters

Greenland shark (Somniosus microcephalus), an Arctic shark, is an unusually slow swimmer, partly because of the impact of the cold waters on muscle function, according to research I've done in the past, Watanabe said, Forbes reported. In addition, they have an abnormally low metabolic rate, a slow pace of growth, and a lengthy lifespan.

Foods are turned into energy for the body to use for its operations through the metabolic process. Even though there have been numerous types of research on the metabolic rates of fish, the majority have focused on teleost (bony) fish rather than sharks or any of their relatives.

Greenland sharks are a kind of sleeper shark that may grow to 23 feet (7 meters), making them the longest-living vertebrate. These sluggish predators, predominantly found in the North Atlantic and Arctic Oceans' frigid waters, consume various aquatic species, including smaller sharks, seals, and fish.

The first estimations of these sharks' resting and active metabolic rates were supplied by a recent study by Eric Ste-Marie, who also discovered that these massive predators only need 61-193 grams of fish or marine mammal prey per day. Watanabe notes Greenland sharks lead a prolonged life, partly because of the chilly waters. However, he wondered whether all fish shared this pattern. Cold-water fish are not usually slow-moving.

As an illustration, Arctic char, a type of salmon found in the Arctic, is a brisk swimmer who lives in the same frigid waters as Greenland sharks. He began to consider that there might be a fundamental distinction between cold temperatures' effects on teleost fish, sharks, and rays.

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Sharks, Rays Vs. Teleost Fish

According to Watanabe's team, teleost fish are more metabolically active in colder temperatures than sharks. This discovery raises a fascinating question: Could this cause the lack of cold-water elasmobranch sightings? Since teleost fish have a wide range of metabolic rates in cold environments, they exhibit a range of lifestyles, from sit-and-wait tactics to swift continuous swimming. According to Britannica, teleost fish adapt well to varied habitats, from cold Arctic and Antarctic oceans that are colder than the freezing point of freshwater to desert hot springs.

As opposed to this, sharks and rays in cold waters nearly lifestyles exhibit low metabolic rates, indicating that they only lead slow lives, as is the case with Greenland sharks. However, a few exceptions exist, such as salmon sharks, with peculiar physiologies and high body temperatures.

According to scientists, sharks and rays in cold waters have few options other than a sedentary existence, which accounts for their rarity compared to teleost fishes in cold seas.

The results of the study were published in Nature.