- Pixabay/Owlstalk
VIVA – Shark is one of the animals that has a large body and dangerous. This animal has been present in the world for almost 450 million years. The species is known to have survived mass extinctions, including the catastrophe that wiped out the Nonavian dinosaurs 66 million years ago at the end of the Cretaceous period. The question is, how did the sharks survive from extinction for this long?
Sharks are known to be older than the dinosaurs that appeared about 240 million years ago, even older than the trees that evolved on Earth about 390 million years ago.
It is because sharks are able to modify their physiology in response to environmental conditions, such as shrinking in size as temperature increases.
This ability allows species to quickly adapt to rapidly changing ecological niches, as quoted from Livescience site on Tuesday, July 26, 2022.
A professor of Marine Biology and Director of the Shark Lab at California State University Long Beach, Chritopher Lowe said that some sharks are unique in that they have very large genomes, which may contain genes that, while useless now, may have allowed them to tolerate the climatic conditions in the past.
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- Freepik
In addition, some species of Elasmobranchii, a subclass of the cartilaginous fish group that includes sharks, can move between freshwater and saltwater environments, a huge physiological challenge.
For example, the notoriously aggressive bull shark (Carcharhinus leucas) is one of the most well-known sharks capable of living in both freshwater and saltwater environments.
This ability is likely to have helped shark species that lived in the past to adapt when global temperatures changed and large amounts of fresh water entered the oceans due to melting ice sheets.
Florida Program Director for shark research, Gavin Naylor also said this flexibility may support the sharks to continue to survive as a group.
Shark is very versatile because it can be found in various types of water such as deep oceans, shallow seas, and rivers. Sharks are also capable of devouring a variety of foods including plankton, fish, crabs, seals, and even whales.
Hiu dan manusia.
In addition, Shark’s adaptability in searching for food may also allow them to survive from extinction.
But, although sharks have managed to avoid mass extinctions before with their adaptability, they are currently facing an unprecedented challenge, such as human activity.
"Sharks have dealt with climate change quite well in the past, but the biggest challenge for the world's sharks and rays today is overfishing," Gavin Naylor remarked.
The role of sharks in the marine ecosystem as a whole cannot be underestimated. Remember, sharks are apex predators that make them able to play an important role in regulating the stability of organisms lower in the food chain.
