Raising temperatures & the Evolutionary Tale of Ancient Sharks
This year, we have experienced unprecedented temperatures of up to 52°C due to unusual patterns in western disturbances. As global experts link these anomalies to human-induced climate change, we explore a similar ancient climate event 93 million years ago that transformed the evolutionary path of sharks.
This year, Calcutta has witnessed unprecedented temperatures soaring up to 49 degrees Celsius, mirroring extreme heat conditions in other parts of the country. The weather department attributes this spike to an unusual pattern in western disturbances. These weather systems, originating in the Mediterranean Sea, typically bring moisture-laden winds that mitigate the impact of the hot, dry air flowing from Pakistan and Afghanistan into northern India. However, while there was an increase in these disturbances between March and early May, their intensity waned over the last “10-15 days,” allowing the hot winds to raise temperatures unchecked.
Global and Indian experts concur that such deviations in weather patterns are exacerbated by human-induced climate change. Yet, today’s discussion isn’t solely about the present. Let’s journey back approximately 93 million years to an era when underwater volcanic activity began spewing lava into the oceans and releasing vast quantities of carbon dioxide into the atmosphere. This cataclysmic event caused sea surface temperatures to surge and oxygen levels near the ocean floor to plummet, leading to a significant die-off in marine life. However, according to recent research, this ancient heat wave might have inadvertently favored the evolution of sharks.
Despite their fierce reputation as swift, open-water predators, most sharks actually reside near the seafloor, suggesting that their ancestors were benthic dwellers. To unravel how some shark species came to dominate the pelagic zone, scientists examined body size and fin morphology across over 500 living and fossilized sharks. They found that ancient sharks had relatively short pectoral fins, which began to elongate as oxygen levels dwindled, likely pushing these fish into open waters.
The new pectoral fin shapes resembled the wings of commercial airplanes, optimizing energy efficiency during movement, as explained by study author Philip Sternes. This adaptation was crucial as it minimized the energy required for locomotion in the vast ocean. Additionally, the elevated ocean temperatures enhanced the sharks’ muscle performance, making them even faster swimmers.
This evolutionary adaptation was significant, allowing sharks to thrive in the altered marine environment. As they ventured into open waters, their streamlined bodies and efficient fins facilitated swifter, more energy-efficient swimming, giving them a competitive edge over other marine predators.
In conclusion, while today’s extreme temperatures underscore the urgent issue of climate change, reflecting on ancient climatic upheavals reveals nature’s remarkable capacity for adaptation. The evolutionary journey of sharks from bottom dwellers to agile open-water predators illustrates how life can persist and transform in response to dramatic environmental shifts. This historical perspective emphasizes the resilience of life, even amid catastrophic changes, and underscores the importance of understanding our past to navigate the climatic challenges of the present and future.