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

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...

venomous Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...

sea snake Sea snakes, or coral reef snakes, are elapid snakes that inhabit marine environments for most or all of their lives. They belong to two subfamilies, Hydrophiinae and Laticaudinae. Hydrophiinae also includes Australasian terrestrial snakes, w ...

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 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. LaticaudaColubrinaSmith

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 permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell. Synapses are essential to the transmission of nervous impulses from ...

s by competing with

acetylcholine Acetylcholine (ACh) is an organic chemical 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, 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, overwo ...

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 associa ...

, 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 sometimes used as a ...

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

hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high b ...

and

cyanosis Cyanosis is the change of body tissue color to a bluish-purple hue as a result of having decreased amounts of oxygen bound to the hemoglobin in the red blood cells of the capillary bed. Body tissues that show cyanosis are usually in locations ...

observed in human sea snake bite victims. Some varieties of eels, which are a primary food source for yellow-lipped sea kraits, may have coevolved resistance to yellow-lipped sea krait venom. '' Gymnothorax'' 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''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torres ...

, 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, semiaquatic can refer to various types of animals that spend part of their time in water, or plants that naturally grow partially submerged in water. Examples are given below. Semiaquatic animals Semi aquatic animals include: * Ve ...

. 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 com ...

, 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, and reproduce. Individuals return to their specific home islands, exhibiting philopatry. 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 (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and e ...

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 marine fish classified in the jack family, Carangidae. The giant trevally is distribute ...

and goatfish. This cooperative hunting technique is similar to that of the

moray eel 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 a few are f ...

, 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 i ...

, Muraenidae, and Ophichthidae), 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 but are now regarded as being ''incertae sedis'' in the subseries Ovalentaria in the clade Perc ...

and

Synodontidae The Synodontidae or lizardfishes(or typical lizardfish to distinguish them from the Bathysauridae and Pseudotrichonotidae) are benthic (bottom-dwelling) marine and estuarine bony fishes that belong to the aulopiform fish order, a diverse grou ...

). Males and females exhibit

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...

in hunting behavior, as adult females, which are significantly larger than males, prefer to hunt in deeper water for larger conger eels, 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 lay their eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, most reptiles, and all pterosaurs, dinosaurs (including birds), and m ...

, 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 (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

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

smoked Smoking is the process of flavoring, browning, cooking, or preserving food by exposing it to smoke from burning or smoldering material, most often wood. Meat, fish, and '' lapsang souchong'' tea are often smoked. In Europe, alder is the tra ...

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: ) is based on rice with miso soup and oth ...

. The smoked meat of a related ''Laticauda'' species, the black-banded sea krait, is used in Okinawan cuisine to make ''irabu-jiru'' ( ja, イラブー汁, ''irabu soup'').

References

External links

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