Understanding Laticauda Semifasciata Sea Snakes

Laticauda Semifasciata sea snakes are a type of venomous snake found in tropical waters.

They are known for their striking appearance, with a brown or grayish-brown color and a distinctive pattern of darker blotches on their backs.

These snakes are found in the coastal waters of the Pacific Ocean, from Japan to Australia.

Their venom is highly toxic and can cause respiratory failure, cardiac arrest, and renal failure in humans.

Laticauda Semifasciata sea snakes are oviparous, meaning they lay eggs rather than giving birth to live young.

They are also known to be nocturnal, spending most of their time hiding in crevices and under rocks during the day.

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We conducted 32 recreational dives at 'the Cathedral', a site located 650 meters off the closest shore in Belongas, south of Lombok Island in Indonesia. The dives took place between September 2018 and July 2022, with a surface water temperature of 27-30°C and 25-27°C at the bottom throughout the year.

The site, which comprises a tall pinnacle surrounded by boulders, experiences high waves and strong currents. We visited the site in groups of two to six, and once encountered, individuals of Erabu sea kraits were opportunistically observed from a distance of around 3 meters.

The researchers observed foraging Erabu sea kraits during 32 recreational dives at a site called 'the Cathedral' in Belongas, south of Lombok Island in Indonesia.

The site is located 650 meters off the closest shore and features a tall pinnacle surrounded by boulders that reach a depth of around 55 meters. It experiences high waves and strong currents.

The surface water temperature at the site ranges from 27 to 30 degrees Celsius, while the bottom temperature is between 25 and 27 degrees Celsius throughout the year.

Deep-diving certified scuba divers visited the site 32 times between September 2018 and July 2022 as part of recreational dive tours, often in groups of two to six.

These divers opportunistically observed the Erabu sea kraits from a distance of around 3 meters, following them for 5 to 20 minutes based on the dive conditions and the kraits' behavior.

On some occasions, the encounters were filmed with GoPro cameras without external lights.

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Erabu sea kraits were encountered on at least 52 separate occasions during the dives.

The number of individuals per dive ranged from two individuals on 21 June 2022 to 21 individuals on 5 October 2019.

They were observed at depths between 23 and 45 m.

Eleven unique behaviours were recorded during the encounters.

Most observations were anecdotal records from recreational dives.

Forty-three separate encounters were of swimming or foraging individuals.

Nine instances were of resting individuals, drifting motionless along the substrate.

Some instances of intraspecific and interspecific communal hunting were observed with apparent coordination.

The sympatric yellow-lipped sea krait was encountered on three dives, but all individuals were solitary and at depths of <20 m.

Individuals of the Erabu sea krait were estimated to be ~100 to ~130 cm in total length.

Sea snake samples were collected from open waters in southern South Korea, where Laticauda semifasciata is not protected.

To obtain these samples, over 200 posters and 50 banners were placed around coastal towns, including Jeju Island, between April 2015 and October 2016.

A total of 12 L. semifasciata were collected and donated by local fishermen, with nine coming from Jeju Island and three from the Korean Peninsula.

These specimens were then delivered to the Herpetological Lab of Kangwon National University, where basic data was collected, including sex, snout-vent length, and body weight.

The researchers took a tail clip from each specimen using scissors, which included the terminal scale, to collect tissue samples.

Additional tissue samples were obtained from four L. semifasciata specimens from Orchid Island, Taiwan, and sequences from the Ryukyu Islands, Japan, were obtained from GenBank.

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Out of 12 snakes from Korea, 11 were female and 1 was male.

The phylogenetic trees inferred using ML and BI were highly similar, only differing by support values and the relationships of some terminal branches.

We identified three different Cytb haplotypes from our specimens, all of which were previously reported from the Taiwan-Ryukyu Archipelago.

The three haplotypes were Semi-1, Semi-3, and Semi-5, which were adopted from a previous study.

Three specimens from Aewol, Moseolpo, and Gangjeong 2 (Jeju Island) and one from Gori (Korean Peninsula) had the Semi-1 haplotype.

One specimen from Wimi (Jeju Island), one from Ilgwang (Korean Peninsula), and four from Taiwan had the Semi-3 haplotype.

The five remaining specimens from Jeju Island (Marado, Gangjeong 1, Seogwipo, Dukdol, and Udo) and one from the Korean Peninsula (Yeosu) had the Semi-5 haplotype.

The 12 Korean samples had only three haplotypes, which could be placed into two major groups based on geography.

Korean samples did not have any haplotypes restricted to either central or northern Ryukyus.

Laticauda semifasciata, also known as the Chinese Sea Krait or Black-Banded Sea Krait, is a species of venomous sea snake found in the coastal waters of the Pacific and Indian Oceans.

The Chinese Sea Krait has a distinctive banded pattern, with black and white or blue and white. They are medium-sized snakes, typically reaching around 1 meter (3-4 ft) in total length.

Their laterally compressed tail is used to propel themselves through the water, and sharp teeth for catching their prey. They primarily prey on small fish, but will also consume crustaceans, cephalopods, and other small marine animals.

Black-Banded Sea Kraits are primarily fish-eaters, and are found in a variety of marine habitats, including coral reefs, lagoons, and mangrove swamps. They are often seen in shallow water but can also be found at depths of up to 60m.

The Chinese Sea Krait is primarily active at night and is known to be quite docile. They are good swimmers and use their laterally compressed tail to propel themselves through the water.

Here is a list of the species' characteristics:

The Chinese Sea Krait belongs to the genus Laticauda, and the scientific name for this species is Laticauda semifasciata. They belong to the Elapidae family, which also includes many other species of venomous snakes such as cobras and mambas.

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