Gray seals have discovered a secret sense that allows them to time their underwater dives with precision, making them less susceptible to drowning during extended dives.
The Secret Sense of Gray Seals
Gray seals have long been a subject of fascination among marine biologists, and a recent study has shed new light on their unique abilities. Researchers at the Sea Mammal Research Unit in Scotland have discovered that gray seals possess a secret sense that helps them survive at sea: they can directly sense their own circulating blood oxygen levels.
The gray seal (Halichoerus grypus) is a large earless seal found in the North Atlantic Ocean.
They have a distinctive gray coat with a lighter underside and can grow up to 2 meters in length, weighing up to 170 kilograms.
Gray seals are skilled hunters, feeding on fish, crustaceans, and mollusks.
They breed on land, typically on rocky shores or islands, and give birth to a single pup after a gestation period of approximately 9 months.
This ability allows gray seals to time their underwater dives with precision, making them less susceptible to drowning during extended dives. The study, published in the journal Science, suggests that gray seals perceive their blood oxygen levels and adjust their dive duration accordingly. This adaptation is crucial for their survival, as it enables them to avoid the risks associated with low oxygen levels.
The Science Behind the Ability
To understand how gray seals achieve this remarkable ability, researchers conducted a study on wild-caught juvenile gray seals. The animals were placed in a pool and exposed to different gas combinations, including ambient air, high-oxygen concentrations, and elevated carbon dioxide levels. The researchers recorded 510 individual dives across all animals and found that the seals spent an average of four minutes underwater after breathing ambient air.
The study revealed that elevating carbon dioxide had no effect on dive time compared with ambient air, suggesting that gray seals are not relying on CO2 as a proxy for low oxygen levels. Instead, they appear to be directly sensing their blood oxygen levels and adjusting their behavior accordingly.
Implications for Marine Mammals
The discovery of gray seals‘ ability to sense their own circulating blood oxygen levels has significant implications for our understanding of marine mammal physiology. It suggests that these animals have evolved a unique adaptation that allows them to survive in aquatic environments, where CO2 can build up and be retained in the body.
This finding also highlights the importance of further research into the cognitive perception of circulating oxygen in seals. As McKnight et al. noted, ‘the study provides compelling evidence that gray seals possess the cognitive ability to perceive oxygen levels, allowing them to regulate their dive duration accordingly.’
There are 32 species of seals found in the world's oceans.
They belong to two main families: Phocidae (true seals) and Otariidae (eared seals).
True seals have flippers, but eared seals have external ear flaps.
Seals can be found in both warm and cold waters, with some species migrating long distances for food or breeding.
They are carnivores, feeding on fish, squid, and krill.
A New Understanding of Marine Mammal Evolution
The study’s findings have also sparked interest in the convergent evolution of diving-related adaptations among marine mammals. The researchers suggest that similar oxygen perception mechanisms may exist across other species, which could provide new insights into the evolutionary pressures faced by these animals.
There are over 130 species of marine mammals, including whales, dolphins, porpoises, seals, sea lions, walruses, and manatees.
These animals inhabit oceans worldwide, from the Arctic to tropical waters.
Marine mammals have adapted to life in water with unique features such as flippers, streamlined bodies, and specialized skin that prevents water loss.
They feed on a variety of prey, including fish, squid, krill, and plankton.
In conclusion, the discovery of gray seals’ secret sense is a remarkable example of the complex and fascinating world of marine mammal physiology. Further research into this topic will undoubtedly shed more light on the unique adaptations that enable these incredible creatures to thrive in their aquatic environments.
- sciencenews.org | Gray seals may sense their own blood oxygen levels
- eurekalert.org | Seals can sense their own circulating blood oxygen and it keeps ...
