The yellow-lipped sea krait (''Laticauda colubrina''), also known as the banded sea krait or colubrine sea krait, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of highly

venomous snake ''Venomous snakes'' are species of the suborder Serpentes that are capable of producing venom, which they use for killing prey, for defense, and to assist with digestion of their prey. The venom is typically delivered by injection using hollow ...

found in tropical

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

oceanic waters. The snake has distinctive black stripes and a yellow snout, with a paddle-like tail for use in swimming. It spends much of its time under water to hunt, but returns to land to digest, rest, and reproduce. It has very potent neurotoxic venom, which it uses to prey on eels and small fish. Because of its affinity to land, the yellow-lipped sea krait often encounters humans, but the snake is not aggressive and only attacks when feeling threatened.

Description

The head of a yellow-lipped sea krait is black, with lateral nostrils and an undivided

rostral scale The rostral scale, or rostral, in snakes and other scaled reptiles is the median plate on the tip of the snout that borders the mouth opening. Wright AH, Wright AA (1957). ''Handbook of Snakes of the United States and Canada''. Ithaca and London: ...

. The upper lip and snout are characteristically colored yellow, and the yellow color extends backward on each side of the head above the eye to the

temporal scales In reptiles, the temporal scales are located on the side of the head between the parietal scales and the supralabial scales, and behind the postocular scales.U.S. Navy. 1991. Poisonous Snakes of the World. US Govt. New York: Dover Publications Inc ...

The body of the snake is

subcylindrical {{Short pages monitor 0.45 mg/kg body weight. The venom is an α-neurotoxin that disrupts

synapse In the nervous system, a synapse is a structure that allows a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or a target effector cell. Synapses can be classified as either chemical or electrical, depending o ...

s by competing with

acetylcholine Acetylcholine (ACh) is an organic compound that functions in the brain and body of many types of animals (including humans) as a neurotransmitter. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Par ...

for receptors on the

postsynaptic membrane Chemical synapses are biological junctions through which neurons' signals can be sent to each other and to non-neuronal cells such as those in muscles or glands. Chemical synapses allow neurons to form circuits within the central nervous syste ...

, similar to erabutoxins and α-bungarotoxins. In mice, lethal venom doses cause

lethargy Lethargy is a state of tiredness, sleepiness, weariness, fatigue, sluggishness, or lack of energy. It can be accompanied by depression, decreased motivation, or apathy. Lethargy can be a normal response to inadequate sleep, overexertion, overw ...

flaccid paralysis Flaccid paralysis is a neurological condition characterized by weakness or paralysis and reduced muscle tone without other obvious cause (e.g., trauma). This abnormal condition may be caused by disease or by trauma affecting the nerves associ ...

, and

convulsion A convulsion is a medical condition where the body muscles contract and relax rapidly and repeatedly, resulting in uncontrolled shaking. Because epileptic seizures typically include convulsions, the term ''convulsion'' is often used as a synony ...

s in quick succession before death. Dogs injected with lethal doses produced symptoms consistent with fatal

hypertension Hypertension, also known as high blood pressure, is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not cause symptoms i ...

and

cyanosis Cyanosis is the change of Tissue (biology), tissue color to a bluish-purple hue, as a result of decrease in the amount of oxygen bound to the hemoglobin in the red blood cells of the capillary bed. Cyanosis is apparent usually in the Tissue (bi ...

observed in human sea snake bite victims. Some varieties of

eel Eels are ray-finned fish belonging to the order Anguilliformes (), which consists of eight suborders, 20 families, 164 genera, and about 1000 species. Eels undergo considerable development from the early larval stage to the eventual adult stage ...

s, which are a primary food source for yellow-lipped sea kraits, may have coevolved resistance to yellow-lipped sea krait venom. ''

Gymnothorax ''Gymnothorax'' is a genus of fish in the family Muraenidae found in Atlantic, Indian, and Pacific Oceans. With more than 120 species, it the most speciose genus of moray eels. notes that ''Gymnothorax'' as currently recognized is polyphy ...

'' moray eels taken from the Caribbean, where yellow-lipped sea kraits are not endemic, died after injection with doses as small as 0.1 mg/kg body weight, but ''Gymnothorax'' individuals taken from

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; , fossilized , also known as Papua or historically ) is the List of islands by area, world's second-largest island, with an area of . Located in Melanesia in the southwestern Pacific Ocean, the island is ...

, where yellow-lipped sea kraits are endemic, were able to tolerate doses as large as 75 mg/kg without severe injury.

Behavior

Yellow-lipped sea kraits are

semiaquatic In biology, being semi-aquatic refers to various macroorganisms that live regularly in both aquatic and terrestrial environments. When referring to animals, the term describes those that actively spend part of their daily time in water (in ...

. Juveniles stay in water and on adjacent coasts, but adults are able to move further inland and spend half their time on land and half in the ocean. Adult males are more terrestrially active during mating and hunt in shallower water, requiring more terrestrial locomotive ability. Adult females, though, are less active on land during mating and hunt in deeper water, requiring more aquatic locomotive ability. Because males are smaller, they crawl and swim faster than females. Body adaptations, especially a paddle-like tail, help yellow-lipped sea kraits to swim. These adaptations are also found in more distantly related sea snakes (

Hydrophiinae Hydrophiinae is a subfamily of venomous snakes in the family Elapidae. It contains most sea snakes and many genera of venomous land snakes found in Australasia, such as the taipans (''Oxyuranus''), tiger snakes (''Notechis''), brown snakes (' ...

) because of

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...

, but because of the differences in motion between crawling and swimming, these same adaptations impede the snake's terrestrial motion. On dry land, a yellow-lipped sea krait can still move, but typically at only slightly more than a fifth of its swimming speed. In contrast, most sea snakes other than ''Laticauda'' spp. are virtually stranded on dry land. When hunting, yellow-lipped sea kraits frequently head into deep water far from land, but return to land to digest meals,

shed skin Shed Skin is an experimental restricted- Python (3.8+) to C++ programming language compiler. It can translate pure, but implicitly statically typed Python programs into optimized C++. It can generate stand-alone programs or extension modules t ...

, and reproduce. Individuals return to their specific home islands, exhibiting

philopatry Philopatry is the tendency of an organism to stay in or habitually return to a particular area. The causes of philopatry are numerous, but natal philopatry, where animals return to their birthplace to breed, may be the most common. The term derives ...

. When yellow-lipped sea kraits on Fijian islands were relocated to different islands 5.3 km away, all recaptured individuals were found on their home islands in an average of 30.7 days. Yellow-lipped sea kraits collected near the tip of

Borneo Borneo () is the List of islands by area, third-largest island in the world, with an area of , and population of 23,053,723 (2020 national censuses). Situated at the geographic centre of Maritime Southeast Asia, it is one of the Greater Sunda ...

had heavy tick infections.

Hunting and diet

Hunting is often performed alone, but ''L. colubrina'' kraits may also do so in large numbers in the company of hunting parties of

giant trevally The giant trevally (''Caranx ignobilis''), also known as the lowly trevally, barrier trevally, ronin jack, giant kingfish, or ''ulua'', is a species of large ocean, marine fish classified in the jack Family (biology), family, Carangidae. The gian ...

and

goatfish The goatfishes are ray-finned fish of the family Mullidae, the only family in the suborder Mulloidei of the order Syngnathiformes. The family is also sometimes referred to as the red mullets, which also refers more narrowly to the genus '' Mul ...

. This cooperative hunting technique is similar to that of the

moray eel Moray eels, or Muraenidae (), are a family (biology), family of eels whose members are found worldwide. There are approximately 200 species in 15 genera which are almost exclusively Marine (ocean), marine, but several species are regu ...

, with the yellow-lipped sea kraits flushing out prey from narrow crevices and holes, and the trevally and goatfish feeding on fleeing prey. While probing crevices with their heads, yellow-lipped sea kraits are unable to observe approaching predators and can be vulnerable. The snakes can deter predators, such as larger fish, sharks, and birds, by fooling them into thinking that their tail is their head, because the color and movement of the tail is similar to that of the snake's head. For example, the lateral aspect of the tail corresponds to the dorsal view of the head. Yellow-lipped sea kraits primarily feed on varieties of eels (of the families

Congridae The Congridae are the family of conger and garden eels. Congers are valuable and often large food fishes, while garden eels live in colonies, all protruding from the sea floor after the manner of plants in a garden (thus the name). The family in ...

Muraenidae Moray eels, or Muraenidae (), are a family of eels whose members are found worldwide. There are approximately 200 species in 15 genera which are almost exclusively marine, but several species are regularly seen in brackish water, ...

, and

Ophichthidae Ophichthidae is a family (biology), family of fish in the order (biology), order Anguilliformes, commonly known as the snake eels. The term "Ophichthidae" comes from Greek language, Greek ''ophis'' ("serpent") and ''ichthys'' ("fish"). Snake eels ...

), but also eat small fish (including those of the families

Pomacentridae Pomacentridae is a family of ray-finned fish, comprising the damselfishes and clownfishes. This family were formerly placed in the order Perciformes or as indeterminate percomorphs, but are now considered basal blenniiforms. They are primaril ...

and Synodontidae). Males and females exhibit

sexual dimorphism Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

in hunting behavior, as adult females, which are significantly larger than males, prefer to hunt in deeper water for larger

conger eel ''Conger'' ( ) is a genus of marine congrid eels. It includes some of the largest types of eels, ranging up to or more in length, in the case of the European conger. Large congers have often been observed by divers during the day in parts of ...

s, while adult males hunt in shallower water for smaller moray eels. In addition, females hunt for only one prey item per foraging bout, while males often hunt for multiple items. After hunting, yellow-lipped sea kraits return to land to digest their prey.

Courtship and reproduction

The yellow-lipped sea krait is

oviparous Oviparous animals are animals that reproduce by depositing fertilized zygotes outside the body (i.e., by laying or spawning) in metabolically independent incubation organs known as eggs, which nurture the embryo into moving offsprings kno ...

, meaning it lays eggs that develop outside of the body. Each year during the warmer months of September through December, males gather on land and in the water around gently sloping areas at high tide. Males prefer to mate with larger females because they produce larger and more offspring. When a male detects a female, he chases the female and begins courtship. Females are larger and slower than males, and many males escort and intertwine around a single female. The males then align their bodies with the female and rhythmically contract; the resulting mass of snakes can remain nearly motionless for several days. After courtship, the snakes copulate for about an average of two hours. The female yellow-lipped sea kraits then lay as many as 10 eggs per clutch. The eggs are deposited in crevices where they remain until hatching. These eggs are very rarely found in the wild; only two nests have been definitively reported throughout the entire range of the species.

Interaction with humans

Because yellow-lipped sea kraits spend much of their time on land, they are often encountered by humans. They are frequently found in the water intake and exhaust pipes of boats. They are also attracted to light and can be distracted by artificial sources of light, including hotels and other buildings, on coasts. Fewer bites from this species are recorded compared to other venomous species such as cobras and vipers, as it is less aggressive and tends to avoid humans. If they do bite, it is usually in self-defense when accidentally grabbed. Most sea snake bites occur when fishermen attempt to untangle the snakes from their fishing nets. In the

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

, yellow-lipped sea kraits are caught for their skin and meat; the meat is smoked and exported for use in

Japanese cuisine Japanese cuisine encompasses the regional and traditional foods of Japan, which have developed through centuries of political, economic, and social changes. The traditional cuisine of Japan (Japanese language, Japanese: ) is based on rice with m ...

. The smoked meat of a related ''Laticauda'' species, the black-banded sea krait, is used in

Okinawan cuisine is the cuisine of Okinawa Prefecture, Japan. The cuisine is also known as , a reference to the Ryukyu Kingdom. Due to differences in culture, historical contact between other regions, climate, vegetables and other ingredients, Okinawan cuisine ...

to make ''irabu-jiru'' (, ''irabu soup'').

References

External links

SeaLifeBase: Laticauda colubrina
{{Taxonbar, from=Q383702 Laticauda Reptiles of Borneo Reptiles of Cambodia Reptiles of China Reptiles of India Reptiles of Indonesia Snakes of Japan Reptiles of Korea Reptiles of Malaysia Reptiles of Myanmar Reptiles of New Zealand Reptiles of Papua New Guinea Reptiles of the Philippines Reptiles of Taiwan Reptiles of Thailand Reptiles of Vietnam Reptiles described in 1907 Taxa named by Johann Gottlob Theaenus Schneider Snakes of Asia Snakes of China Snakes of New Guinea Snakes of Vietnam Articles containing video clips