Sea Snakes Possess Venom Potency Surpassing That of Rattlesnakes

Life in the tropical ocean poses unique challenges for air-breathing sea snakes. For example, while they shed their skin like other snakes, the absence of rocks or reefs in open waters makes finding friction for the process difficult.

Despite these hurdles, the over 50 species of sea snakes have developed remarkable adaptations to thrive in their aquatic habitats.

Sea Kraits vs. True Sea Snakes

Not every snake found in the ocean qualifies as a "sea snake." Numerous unrelated species occasionally venture into marine environments. For instance, Reticulated pythons are known to swim between islands in the coastal and coral reef regions of Southeast Asia, covering distances that would challenge even an Olympic champion.

However, this behavior does not classify them as sea snakes.

In scientific terms, "sea snakes" typically refer to two distinct groups within the cobra family (Elapidae): true sea snakes (Hydrophiinae) and sea kraits (Laticaudinae).

Despite their differences, sea kraits and true sea snakes share many similarities. Both possess paddle-like tails that enable them to navigate aquatic environments with ease.

Hydrophiinae

Yellow-bellied sea snakes are quintessential hydrophiids. These true sea snakes have completely abandoned land, living entirely in marine environments where they give birth to live offspring. Researchers have discovered that Cleveland Bay in Australia serves as a biological nursery, attracting pregnant spine-bellied sea snakes to deliver their young.

Giving birth on land is impossible for hydrophiids. They never leave the water willingly, as they lack the broad ventral scales that enable other snakes to crawl on land. If placed on a beach, these creatures will struggle to move independently.

Laticaudinae

Sea kraits are slightly less hydrodynamic but excel on land. They engage in mating, shedding, and digesting some of their meals outside aquatic environments. With the necessary ventral scales, they can move on land and, similar to sea turtles, lay their eggs in nests on the beach.

Deathly Serious Venom

Even the most venomous sea snakes rarely pose a fatal threat to humans. These creatures are generally gentle around people. Bites typically occur when a snake feels cornered or stressed; for instance, a banded sea krait fatally bit a man in 2018 after being caught in a fishing net.

Most sea snakes deliver venom through hollow fangs located at the front of their mouths. To conserve their venom, a threatened sea snake often delivers "dry bites" — striking without releasing any venom.

It's best to keep your distance. The neurotoxins in sea snake venom target the nervous system, potentially causing paralysis, muscle spasms, and breathing difficulties as the toxins take effect.

Sea Snake Hunting Patterns

Sea snakes primarily prey on small fish abundant in coastal waters. Occasionally, they employ a passive hunting strategy: The yellow-bellied sea snake remains still at the water's surface, luring unsuspecting fish to seek shelter beneath its coils before capturing them.

Some snakes extract fish from the nooks and crannies of coral reefs. These hiding spots are often frequented by eels, the preferred prey of banded sea kraits. Despite the risks posed by morays, kraits subdue them with their potent venomous fangs and then consume them whole.

Certain species, such as the spine-tailed sea snake, exclusively feed on fish eggs. These specialists possess small fangs and, in at least one case, extremely mild venom. Since fish eggs cannot escape, there's no need to paralyze them.

Drinking Rain From the Ocean Surface

Sea kraits and hydrophiids cannot drink seawater, so they rely on alternative methods to stay hydrated. Sea kraits have been seen licking fresh water droplets from plant leaves when on land. After rainstorms, they often gather on islands to drink from puddles.

Rainfall over the ocean creates a fascinating effect. Freshwater droplets accumulate on the surface, forming a temporary, drinkable "lens." Yellow-bellied sea snakes take advantage of this, drinking from these lenses before the rainwater becomes too salty.

Both sea kraits and true sea snakes have specialized valves that close their nostrils to prevent water entry during dives. Certain species can remain submerged for up to three and a half hours at a time.

Neither group has gills, but in 2019, scientists discovered that the blue-banded sea snake (a true sea snake) uses intricate blood vessels in its head to extract oxygen directly from the water. A remarkable adaptation indeed.

Sharks, crocodiles, and certain predatory birds will prey on sea snakes when the opportunity arises. To deter predators, the yellow-lipped sea krait has evolved markings that make its tail resemble a second head.

Sea Snakes in the Pacific Ocean

Pollution poses a significant threat, particularly to snakes that inhabit and feed near industrial areas.

Long before human pollution became an issue, sea snakes had already colonized the Pacific and Indian Oceans. Two landlocked lakes in the South Pacific — Lake Taal in the Philippines and Lake Tenago in the Solomon Islands — are also home to unique resident species.

However, you won't find them in the Atlantic.

The Atlantic Ocean, Earth's second-largest, is devoid of sea snakes. This absence may be due to geography and climate. Researchers believe the ancestors of these marine reptiles evolved in the western Pacific 6 to 8 million years ago. By the time modern species could have reached the Americas, the Panama land bridge connecting North and South America might have already formed.

Cold waters are lethal to sea snakes, making it impossible for them to navigate around South America's Cape Horn. Additionally, Africa's southeastern coast receives minimal rainfall, creating a harsh environment for hydration. Even the most resilient creatures have their limits.