Anglerfishes colonised the ocean some 55 million years ago by becoming sexual parasites, a new study has revealed. The unique fishes, which are found in the ocean’s midnight zone, adapted to the deep sea environment during a period of extreme global warming, the researchers said.

Anglerfishes are one of the most diverse vertebrate groups in the deep sea. They have unique features including bioluminescent lures. The light from these organs attracts prey towards them, which they use as their weapon to prey on other species.&nbsp;

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Many anglerfish species roam on the seafloor, a zone ranging from the near shore to depths of thousands of feet. They walk along the bottom using modified fins that look like legs. But others live in the deep open water of the bathypelagic, or midnight zone, which is 3,000 to 13,000 feet (900 to 4,000 meters) below the surface.

<h2>How anglerfishes survived the ocean’s midnight zone?</h2>

The recent study by BioRxiv suggests anglerfish of the group Ceratioidea colonised this midnight zone during the Paleocene-Eocene Thermal Maximum, which occurred 55 million years ago and lasted for around 200,000 years.

The period, researchers believe, may have been initiated by volcanic events that released methane into the atmosphere. The temperatures were so extreme that polar seas reached temperatures of up to 23 degrees Celsius, while sea surface temperatures may have gotten as warm as 36 degrees Celsius.

This led to a wipe-out of numerous deep-sea organisms that likely opened up new ecological niches, the study suggests. It was this window that allowed ceratoid anglerfish to adapt to new surroundings and exist even under changing climates.

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"What we found is that they went into the deep ocean, much like whales going back into the ocean from walking ancestors," lead author Chase Brownstein, a first-year graduate student at Yale, told Live Science.

"Anglerfish just did it in reverse. They were walking on the ocean floor and they went back up into the water column."

Living in the midnight zone means having no real home as there are no reefs, caves, seaweed or other substrate to lean on to. Hence, this environment is not conducive to mating, but researchers suggest anglerfish adopt new breeding strategies to come out of this problem.&nbsp;

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First, they seem to locate each other by scent. And then males fuse to their potential partners permanently, by merging with the bodies of females. In some cases, only one male fuses with the female. In others, even multiple males were found attached to the female.

This unique reproductive strategy is the result of immune system deficiencies, which proved advantageous during this period of radical ecosystem change, which allowed anglerfish to survive in the depths of the ocean.

(With inputs from agencies)

Anglerfishes colonised the ocean some 55 million years ago by becoming sexual parasites, a new study has revealed. The unique fishes, which are found in the ocean’s midnight zone, adapted to the deep sea environment during a period of extreme global warming, the researchers said.

Anglerfishes colonised the ocean some 55 million years ago by becoming sexual parasites, a new study has revealed. The unique fishes, which are found in the ocean’s midnight zone, adapted to the deep sea environment during a period of extreme global warming, the researchers said. Anglerfishes are one of the most diverse vertebrate groups in the deep sea. They have unique features including bioluminescent lures. The light from these organs attracts prey towards them, which they use as their weapon to prey on other species. Also Read | Bumblebee species can survive underwater for up to a week, reveals new study Many anglerfish species roam on the seafloor, a zone ranging from the near shore to depths of thousands of feet. They walk along the bottom using modified fins that look like legs. But others live in the deep open water of the bathypelagic, or midnight zone, which is 3,000 to 13,000 feet (900 to 4,000 meters) below the surface. How anglerfishes survived the ocean’s midnight zone? The recent study by BioRxiv suggests anglerfish of the group Ceratioidea colonised this midnight zone during the Paleocene-Eocene Thermal Maximum, which occurred 55 million years ago and lasted for around 200,000 years. The period, researchers believe, may have been initiated by volcanic events that released methane into the atmosphere. The temperatures were so extreme that polar seas reached temperatures of up to 23 degrees Celsius, while sea surface temperatures may have gotten as warm as 36 degrees Celsius. This led to a wipe-out of numerous deep-sea organisms that likely opened up new ecological niches, the study suggests. It was this window that allowed ceratoid anglerfish to adapt to new surroundings and exist even under changing climates. Also Read | Winchcombe meteorite is a ‘jigsaw of seven jigsaws’, finds latest analysis "What we found is that they went into the deep ocean, much like whales going back into the ocean from walking ancestors," lead author Chase Brownstein, a first-year graduate student at Yale, told Live Science. "Anglerfish just did it in reverse. They were walking on the ocean floor and they went back up into the water column." Living in the midnight zone means having no real home as there are no reefs, caves, seaweed or other substrate to lean on to. Hence, this environment is not conducive to mating, but researchers suggest anglerfish adopt new breeding strategies to come out of this problem. Also Read | Ancient humans lived in THIS vast lava tube in Saudi Arabia 7,000 years ago First, they seem to locate each other by scent. And then males fuse to their potential partners permanently, by merging with the bodies of females. In some cases, only one male fuses with the female. In others, even multiple males were found attached to the female. This unique reproductive strategy is the result of immune system deficiencies, which proved advantageous during this period of radical ecosystem change, which allowed anglerfish to survive in the depths of the ocean. (With inputs from agencies)

Anglerfish survived the ocean's midnight zone by becoming sexual parasites

The total number of open-water species living in tropical marine zones has halved in the last four decades, new research finds. The study, published on April 5, claims that climate change-driven factors increased the sea surface temperatures in the tropics by nearly 0.2 degree Celsius.

Many other factors including overfishing have impacted the ocean inhabitants but scientists in the study published in the Proceedings of the National Academy of Sciences found a strong correlation between decline of species and increasing temperature.

The researchers also found that species of fish plateau or decline at or above 20 degree Celsius.

Previous studies have shed light on how high temperatures are driving species of fish to cooler waters. But the new study is broader in scope, for it analysed data from 48,661 marine species that include fish, birds, mollusks, and corals that have been widely seen since 1955.

Also read:&nbsp;<a href="https://www.wionews.com/science/plants-help-reduce-toxic-mercury-from-environment-says-study-375199" hreflang="en">Plants help reduce toxic mercury from environment, says study</a>

The number of species that remain attached to the seabed, including corals and sponges showed stability in the tropics between the 1970s and 2010. In fact, many of these species were found beyond the tropics, suggesting that they were able to spread out.

Essentially, species capable of physical movement are huddling to get close to cooler waters, while those attached to the seafloor are simply awaiting death.

As species of fish move away from the tropics, the coral ecosystems could perish, along with industries that rely on corals.

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The total number of open-water species living in tropical marine zones has halved in the last four decades, new research finds. The study, published on April 5, claims that climate change-driven factors increased the sea surface temperatures in the tropics by nearly 0.

The total number of open-water species living in tropical marine zones has halved in the last four decades, new research finds. The study, published on April 5, claims that climate change-driven factors increased the sea surface temperatures in the tropics by nearly 0.2 degree Celsius. Many other factors including overfishing have impacted the ocean inhabitants but scientists in the study published in the Proceedings of the National Academy of Sciences found a strong correlation between decline of species and increasing temperature. The researchers also found that species of fish plateau or decline at or above 20 degree Celsius. Previous studies have shed light on how high temperatures are driving species of fish to cooler waters. But the new study is broader in scope, for it analysed data from 48,661 marine species that include fish, birds, mollusks, and corals that have been widely seen since 1955. Also read: Plants help reduce toxic mercury from environment, says study The number of species that remain attached to the seabed, including corals and sponges showed stability in the tropics between the 1970s and 2010. In fact, many of these species were found beyond the tropics, suggesting that they were able to spread out. Essentially, species capable of physical movement are huddling to get close to cooler waters, while those attached to the seafloor are simply awaiting death. As species of fish move away from the tropics, the coral ecosystems could perish, along with industries that rely on corals. Also read: Chemicals found in over 1,200 foods linked to damage of immune system

Climate change has halved number of species in tropical waters, new study finds

Seeing a humpback whale swim, breach the surface of the sea and majestically crash back into the ocean is a breathtaking experience and according to a Brazilian environmental organization the giant mammals are even happier this year due to a decrease in shipping following the coronavirus crisis.

Humpback whales put on spectacular show while in Brazil for mating season

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Anglerfish survived the ocean's midnight zone by becoming sexual parasites

Climate change has halved number of species in tropical waters, new study finds

Humpback whales put on spectacular show while in Brazil for mating season