Yellow-bellied sea snake, *Hydrophis platurus*

Detailed introduction

The yellow-bellied sea snake (scientific name *Hydrophis platurus* , formerly known as *Pelamis platurus* ) is a medium-sized, highly venomous marine snake belonging to the genus *Hydrophis* in the family Elapidae. It is one of the most widely distributed sea snakes in the world, found almost throughout the tropical and subtropical Indo-Pacific waters. It spends its entire life in the sea surface and nearshore waters, rarely venturing ashore.

Classification and nomenclature

The yellow-bellied sea snake belongs to the class Reptilia, order Squamata, suborder Serpentes, family Elapidae, and genus Hydrophis . It was previously classified under the monotypic genus *Pelamis* , known as *Pelamis platurus* , but based on molecular systematics and morphological studies, most scholars have now placed it under the genus *Hydrophis *. Its English name, Yellow-bellied Sea Snake, directly describes the bright yellow banded markings on its sides and belly, making it one of the most representative sea snakes of the tropical open seas.

Appearance features

The yellow-bellied sea snake has a slender body, with adults typically reaching 80–100 cm in total length, though larger individuals can exceed 1.2 meters. The back and upper sides are mostly black or dark brown, while the lower sides and belly are a bright yellow to yellowish-orange, creating a striking contrast. Some individuals also exhibit irregular, wavy demarcation along their sides. The tail is highly laterally compressed, resembling a paddle blade, a typical "paddle tail" that aids in efficient swimming in seawater. The scales are small and smooth, and the body surface has an oily secretion that reduces water resistance and prevents immersion. The head is slightly small and flattened, with medium-sized eyes and round pupils; the mouth is slightly elongated posteriorly, and the upper jaw possesses fixed anterior groove fangs, a typical structure for sea snake fangs.

Distribution range and habitat

The yellow-bellied sea snake is recognized as one of the most widely distributed sea snakes, found extensively in the tropical and subtropical waters of the Indian and Pacific Oceans. Its range extends from the coast of East Africa and the Red Sea, through the Indian Ocean, the Southeast Asian archipelago, the South China Sea, and the northern and eastern waters of Australia, all the way to the central Pacific and the Pacific coast of Central and South America. They primarily inhabit the surface waters of open and nearshore waters, often active in the high seas tens or even hundreds of kilometers from the coastline, and can also be found in some nearshore harbors and lagoons. Yellow-bellied sea snakes spend most of their time floating near the surface, moving using ocean currents and wind direction, and rarely come ashore. Even if pushed ashore by storms or currents, their survival time on land is very limited.

Lifestyle Habits and Behaviors

Yellow-bellied sea snakes are typical marine snakes, spending most of their time at or a few meters below the surface. They are adept at "floating" on the sea surface and are often observed "floating in groups" or gathering in large numbers with ocean currents. Yellow-bellied sea snakes can hold their breath for extended periods, diving for tens of minutes at a time, obtaining oxygen through auxiliary gas exchange via their lungs and skin. They often swim near the surface or drift semi-passively with the waves and currents. Once they spot prey or feel threatened, they rapidly move their bodies and flattened tails to accelerate. Although yellow-bellied sea snakes are highly venomous, they generally do not attack humans proactively; most bites occur during accidental contact or fishing operations.

feeding habits

Yellow-bellied sea snakes primarily feed on small fish, especially slender ones and fry, such as eel larvae and small bottom-dwelling fish. They mostly inhabit the water's surface or shallow layers, using their sight and sense of smell to locate schools of small fish. They then swiftly pounce and bite, paralyzing their prey by injecting venom before swallowing them whole. Due to their relatively small size, they typically choose slender, easily swallowed fish and rarely prey on larger animals.

Reproduction and life cycle

Yellow-bellied sea snakes are viviparous, completing almost their entire life cycle in the sea and never needing to come ashore to lay eggs. The breeding season varies depending on the sea area and water temperature, generally occurring during the warmer months. After mating, the embryo develops inside the female for several months, eventually being born directly as a young snake fully adapted to marine life. A litter typically consists of several to more than ten offspring. Newborn snakes can swim and prey on small fish immediately after birth. Precise data on the lifespan of yellow-bellied sea snakes in the wild is unknown, but it is generally estimated that they can live for about ten years or even longer.

Relationship with humans

Yellow-bellied sea snakes are widely distributed in major shipping and fishing areas. They are occasionally entangled in fishing nets, longlines, or drifting debris, and may also be washed ashore after storms. Their venom is highly neurotoxic and myotoxic; experimental studies show it to be extremely potent. However, yellow-bellied sea snakes are generally docile and do not attack unprovoked. Human bites often occur when attempting to remove sea snakes from fishing nets or boats, or when accidentally grasping or stepping on an individual. For those working at sea, it is recommended to wear protective gloves, avoid handling unidentified sea snakes with bare hands, and immediately apply pressure to the wound and seek medical attention as soon as possible if a bite occurs.

Protecting the status quo and threats

In current global assessments, the yellow-bellied sea snake is generally considered a widely distributed species with relatively stable populations, approaching the IUCN "Least Concern" category. However, in certain marine areas, the species may still be affected by factors such as bycatch, marine plastic entanglement, seawater pollution, and changes in sea surface temperature. As a typical offshore sea snake, it is highly sensitive to the health of marine ecosystems. Measures to conserve the yellow-bellied sea snake include: reducing bycatch and marine plastic pollution, strengthening monitoring of nearshore and offshore ecosystems, and raising public awareness of sea snake diversity and the importance of marine conservation through public education.