ADW: Laticauda colubrina: INFORMATIONGeographic Range. Laticauda colubrina, also known as banded sea kraits, originated in the region of northern Papua New Guinea. This species of sea krait is the most widely distributed of the Laticauda complex which includes the related species, Laticauda colubrina and Laticauda saintgirosi. The breeding range of banded sea kraits is limited to the Australian and Oriental Oceanic geographic ranges. Because they inhabit coral reefs and live mostly off the coast of small islands, they have a patchy geographic distribution, a characteristic off most sea snake species. Generally, they are widespread through Indo- Australian Archipelago, the Bay of Bengal, Thailand, Malaysia, and Singapore. More specifically, the breeding range extends westward to the the Andaman and Nicobor Islands and northward to Taiwan and the Miyako and Yaeyaema island groups in the southwestern part of the Ryukyu Archipelago in southern Japan. They are present off the coast of Thailand but only on its western coast. Their eastern limit is Palua and they are present on the island groups from the Solomon Islands to Tonga in the southwestern Pacific. Their distribution is heavily reliant on several key factors including the presence of coral reefs, sea currents, suitable terrestrial shelter, and paleography. They are not found in the Atlantic and Caribbean oceanic regions. Many are found off the shore of small islands and they often hide in small crevices or under rocks. Their primary habitat is shallow coral reef waters where their primary food source (eel) resides. ![]() They have many special adaptations for diving including a saccular lung allowing them to dive to depths up to 6. They spend a much of their lives in the ocean but also spend anywhere between twenty- five and fifty percent of their life on rocky islets in order to court, mate, lay eggs, digest food, and shed their skins. They can also be found in mangrove areas. They are not characterized as a pelagic species. Their heads are mostly black with a yellow band extending along the lip, underneath each eye. They also have a yellow snout and a yellow band above the eye. Similarly, their tails have a U- shaped yellow marking along the edge that borders a broad black band. Twenty to sixty- five black bands form rings around the body. Their ventral surface is typically yellow or a cream color. There is apparent sexual dimorphism in the species most likely due to differences between male and female feeding patterns. Females feed on a larger species of eel that lives in deeper water while the males feed on smaller eels that inhabit shallow water. Therefore, females, weighing about 1. One giant sea krait has been reported at 3. Also, their amphibious nature contributes to their morphological characteristics. For example, they lay eggs and digest food on land and have terrestrial adaptations similar to other terrestrial snakes such as a cylindrical body shape and ventral scales for crawling and climbing on land. Yellow Banded KraitHowever, they hunt and catch prey in the ocean and have certain aquatic adaptations for life in the water including valvular nostrils, salt glands, and a laterally compressed, paddle- like tail similar to true sea snakes. Because of the geographic distribution of the sea kraits, groups from different islands may vary in some physical characteristics such as head shape and size. They do not undergo any metamorphosis. They display determinant growth with rapid growth in young sea kraits which gradually ceases shortly after sexual maturity is reached. Males reach sexual maturity at about one and a half years and females are sexually mature at one and a half to two and a half years. However, not much has been studied on the specific topic of development in banded sea kraits. Males have two of these reproductive organs and, although both are fully functional, only one is used in any given mating. They are sheathed and lie at the base of the tail. During mating, one of the hemipenes protrudes from its sheath and turns inside out. In this conformation, its surface is covered with spikes and hooks that help secure in the cloaca of the female while mating. The first phase is called the tactile phase. Males may swim around the shore attempting to find the point of exit of a female that has gone to land. This phase demonstrates the reliance of the sea kraits on pheromonal cues in order to locate and follow the trail of a female. The second phase includes mounting and body alignment. In this stage, a male will drape itself over a female and often twitch spasmodically in an attempt to stimulate the female. Finally, the third phase refers to the actual copulation of the sea kraits. ![]() Yellow Lipped Sea KraitCopulation in sea kraits involves the insertion of the hemipenis of the male into the cloaca of the female. In a study of mating groups on a small Fijian island, 5. However, males do not appear to exhibit any interaction or competition. Also, in the vast majority of cases, only one male actively courts with a female while the others simply wait and maintain contact with the female. This may reveal two different strategies for male courtship in sea kraits. In one strategy, the male actively tries to stimulate the female until it is ready to copulate. Laticauda species feed in the ocean. In the other strategy, a male is opportunistic, waiting for the moment in which the female is ready to copulate, then rapidly aligning its cloaca with that of the female. Therefore, in contrast to some other snake species, reproductive success in males seems independent of their body size and strength. On the other hand, the attractiveness of females does have a direct correlation with body size as larger females are more frequently and intensely courted. Also, females rarely show any overt response during the courtship process however they may signal by waving their tails when they are ready to copulate. Laticauda colubrina is a widespread. In some populations, such as those in the Philippines, the breeding is aseasonal. However, in other populations of Laticauda colubrina, like those in Fiji and Sabah, it is seasonal with the main mating period occurring during the three month period from September to December. In these populations, the eggs typically hatch from June to August. Like other species of Laticauda, these sea kraits are oviparous and return to land to lay their eggs. However, their clutch size is also subject to geographical variation. For example, clutch size has been reported as 4 to 1. Fiji and 1. 4 to 2. New Caledonia. Gestation period has been difficult to document because of asynchronous breeding in many populations of Laticauda colubrina. Also, little has been researched and understood in regards to hatchling sea kraits. Their average birth mass and time to independence is unknown and requires further research. Females lay eggs on the shore but it is unclear if they return to the sea or stay on shore to care for their eggs. It has been documented that females tend to spend more time on land than males do, but hypotheses of whether this is due to parental investment or a different, unrelated cause has not been tested. More research is required to determine by what modes and to what extent, parents care for their young in this species. However, it has been suggested that sea snakes generally exhibit a relatively high rate of mortality especially in their young. It is unknown if this trend is upheld in this species. In captivity, sea snakes have proven to be difficult to maintain and often refuse food, become anorexic, and die in a short time due to variety of known and unknown causes. In at least one case study, some of the known causes of death in captive Laticauda colubrina were sepsis secondary to a necrotizing enteritis or pneumonia, multi- organ granulomas and sepsis, and multicentric lymphoid neoplasia with secondary sepsis. These are some problems that cause limited lifespan for the banded sea krait in captivity and, because of this, the species is rarely kept in institutions in the United States. When on land, sea kraits adapt to a typical serpentine form of locomotion on firm surfaces. Interestingly, when it encounters loose substrates such as dry sand it conforms to a . This extension expands lung volume compensating for the limited volume of a tubular lung necessitated by the body shape of a snake. During inhalation, stale air in the lung moves into the saccular lung so that vascular surfaces in the lung can contact fresh air. This mechanism leads to prolonged submergence time. Some have estimated that they spend about 2. The majority of their activity occurs at night or at dusk but they are not usually classified as out- right nocturnal animals. During the day, they often congregate in small groups seeking shelter in rock crevices, tree roots, tree holes, and under beach debris. They typically alternate periodically from shade to sun in order to thermoregulate. However, they typically disperse over a wider range of coral reef and coastline in search of food. Unfortunately, the specific size of their home range has not been well researched. In general, sea kraits and true sea snakes have well- developed eyes and Jacobson's organs but lack the heat- sensing organs found in some terrestrial snakes. Also, one study researching the reproductive behavior highlighted the vomeronasal system as a critical part of communication between males and females during reproductive processes. Contact pheromones provide the most critical cues for courtship. Males follow the trail of a female in order to court the female. Also, tongue- flicking was noticed and may be a visual communication cue. The lipid composition in the skin of conspecific males and females differs between sexes and potentially provides another cue for species and sex recognition. Regardless of geographic location, they have a diet consisting almost entirely of eels of the order Anguilliform and families Congridae, Muraenidae, and Ophichthidae. Females and males typically differ in their food habits leading to the sexual dimorphism in the species.
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