The vast oceans are home to a multitude of captivating creatures, and among the most enigmatic are sea snakes. These reptiles have adapted to marine environments and are known for their unique characteristics and behaviors.
Sea snakes are found in the warm waters of the Indian and Pacific Oceans, particularly in the Coral Triangle, the Andaman Sea, and the Great Barrier Reef, but not in the Red Sea, Atlantic Ocean, or Caribbean Sea. They are not fish but reptiles, like turtles, and must surface to breathe.
There are two subfamilies of sea snakes: Hydrophiinae (true sea snakes) and Laticaudinae (sea kraits). True sea snakes are fully aquatic and spend their entire lives in the ocean. They have ribbon-like bodies, which make them strong swimmers, and flattened tails to propel them through the water. The yellow-bellied sea snake (Hydrophis platurus) is a true sea snake that lives a pelagic life and never goes on land. Sea kraits, on the other hand, are semi-aquatic, with cylindrical bodies that enable them to crawl on land. The banded sea krait (Laticauda colubrina) is a sea krait often seen on reefs and is adapted to a life between land and the ocean. True sea snakes comprise around 53 species, while sea kraits have only five.
Both true sea snakes and sea kraits have flattened tails that aid in swimming. They are air-breathing organisms, and while many need to resurface every half hour to breathe, some species, like the yellow-bellied sea snake, can stay submerged for up to eight hours. This is due to their ability to absorb about 33% of their required oxygen and eliminate 90% of carbon dioxide through their skin. True sea snakes also have nostrils on top of their snouts that close when underwater.
Sea snakes are venomous, but are not typically aggressive towards humans. They will only bite if they feel threatened or provoked. They are not poisonous to eat. They are carnivores and mainly prey on fish, fish eggs, and young octopuses. Sea kraits, which are nocturnal feeders, primarily eat eels, but will also eat crabs, squid and fish. While sea kraits return to land to digest their prey, true sea snakes remain in the water. Sea snakes have special sublingual glands under their tongues that allow them to remove excess salt from their blood. They use their tongues to “taste” molecules in the water.
Sea snakes reproduce by laying eggs. Sea kraits are oviparous, meaning they lay eggs externally, typically on land. The banded sea krait often returns to the same beach where it was born to lay up to 10 eggs. True sea snakes are viviparous, meaning they give birth to live young, with the embryos developing inside the mother’s body. This adaptation gives the newborn snakes a higher chance of survival in the open ocean.
Sea snakes have other unique senses as well. They have mechanoreceptors that help them sense vibrations and movement. Some sea snakes also respond to pheromones to identify potential mates. They may even have the ability to detect electromagnetic fields and pressure.
Sea snakes face threats such as pollution, overfishing, and habitat destruction. They can also be caught as bycatch in fishing nets. Conservation efforts are needed to protect these animals and their ecosystems.
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