Type: Research Essays
Sample donated: Janie Parker
Last updated: September 28, 2019
Abstract :The yellow-bellied sea snake, the Pelamis Platurus is a snake living in the sea that a part of the land snake, elapid (Therefore they have really strong venom). This species is most widely distributed snake in the world, and they are found in eastern Africa, South America, and the northern part of Japan, etc… They are mainly living in the tropical parts of the ocean, which has the temperature 18? – 20?, since this species require minimum 16? for long-term surviving.
Their body color is vivid yellow on their downside and jet black on their backside. The body shape is narrow, long and flattened for the tail to facilitate swimming. They have many unique features to adopt for the life in the sea, such as the body shape, skin and Posterior sublingual gland. They reproduce where the temperature is greater than 20?, 1 to 10 living young snakes after about 5 months, since they are ovoviviparous. They often habitat in the drift line, to catch the fish in there which thought that the Pelamis Platurus was debris and tried to hide. They eat any fish that they can ingest.
The sea snake’s ancestor is same as a land snake, which is sea-lizards, and more modern ancestor is a part of elapid, which was living on the land.Introduction :I chose to research Pelamis Platurus, the common name is Yellow-bellied snake for this research paper, because I thought this species is not well-known, therefore it is a very good chance to learn about the species which I might never know. Also, when I was searched “Sea Snake” on google, this species, Pelamis Platurus was very attractive by its vivid yellow and black body color, therefore I decided to research about them.I will discuss about Pelamis Platurus in terms of Classification, Taxonomy, Location/Range, Anatomy, Physiology, Reproduction & Development, Behavior, Ecology, Habitat, Natural History and other information.Location / Range : This species, Pelamis Platurus is a most widely distributed snake in the world, and widespread in the tropical parts of the Pacific and Indian Oceans, whose temperature is between 18 – 20 ? isotherms.
They require minimum 16 – 18 ? for long-term surviving. From the coasts of eastern Africa, north to the Arabian Gulf, east along the Asian coast of the Indian Ocean to the Pacific Ocean, north ward to Japan and eastward to the western coasts of the Americas are an example of suitable milieu for their surviving.Anatomy : They have a head which is narrow, elongated, flattened and triangular with nostrils set high on the top. The body is long and narrow, also flattened. The tail is even more flattened to facilitate swimming, forward and backward. In their mouse, there are many sharp teeth and small fangs on the front of the upper jaw, which secrete venom. Their color of the body is black or dark brown, with a pale and bright yellow underside which extends up the sides. However, sometimes there is the one with all yellow color or the one with darker underside because of xanthic or melanism, which is the deviance of the yellow and black pigment of their skin (usually too much color pigments).
And Their tail has some black spots or bars. They have scales on their body surface same as the terrestrial snakes, however, their scales on the abdomen is degenerate because they are completely aquatic animals, therefore, it is suitable for swimming and they do not need to walk on the ground. However, as a result, they fit aquatic environment completely, they can not go back to the ocean when they run aground accidentally and they die for high percentages. Also, they are the complete aquatic organism, however, they are air-breathing. They still need to go to the surface of the ocean to exchange the gases to respiration, however, they have a unique elongated cylindrical lungs, therefore they are able to spend 30 minutes to 3 hours between the breath.Additionally, they have a gland, known as a Posterior sublingual gland, which sits under the tongue, to excrete salts to avoid excess salt accumulations from the sea water.Physiology : The Pelamis Platurus’ type of thermoregulation is ectothermic since the temperature of the water around them and their body temperature are similar at the same time.
Their average body temperature is slightly higher than ambient temperature, which is 18.8 – 32.5? by the table above. And because of it, they need to control their body temperature by moving their position in the ocean. When the surrounding water has unusual high temperature, like 32?, they try to dive to avoid surface which more sunlight comes in and tend to be how. Contrarily, as the water cooled, they spend more time on the surface with less activeness.
And their back’s color is black, and this coloration facilitates absorption of solar energy. They spend most of their life underwater, a study estimated about 87% of their life, and they mainly surface when the sea is calm.Also, as I mentioned in Anatomy section, the Pelamis Platurus is an air-breathing organism, however, they are carrying some cutaneous respiration system. Therefore they can diffuse the 33% of its oxygen in the water into their blood directly and the waste, carbon dioxide into the water via their skin.
They shed their old skin often same as other snakes, however, the sea snakes including Pelamis Platurus shed their old skin more often than land snakes. It helps to rid off their fouling marine organisms such as algae, barnacles, and bryozoans (the parasites), besides for the growth alone.Reproduction and Development : This species, Pelamis Platurus reproduces sexually, therefore it involves both female and male snakes and mating directly. Usually, it takes place near the surface, and the temperature needs to be greater than 20? or 68 °F. The Pelamis Platurus is ovoviviparous, which they reproduce the young snakes directly into the water after they incubate their eggs in their womb.
At one time, 1 to 10 youngs are born, and at birth, their body length is 220-260 mm long. Then the adult males are able to grow greater than 600mm. Both seasonal and non-seasonal reproduction were assumed for the populations in Central America, the female snakes in Central America may travel to the Gulf of Panama to give birth.
Also, in the New South Wales population, gravid female snakes were found in July. They are the completely aquatic organism, therefore they do not need to go to shore when they reproduce, unlike other sea snakes (some species are oviparous and reproduce at the shore).Behavior : As I wrote in the Reproduction / Development section, they are ovoviviparous, therefore after the female snake fertilized, they keeping the eggs in their womb until the eggs incubate, around 5-6 months. After each youngs are incubated, the parent snakes will not take care of them, therefore the young snakes will live alone since they are born. The intelligence of them are not high as some marine mammals, however, if the imitation of debris is intentional, that might be an evidence that they have a bit of intelligence.
The longevity of them is around 2-4 years, and it is quite short comparing to the normal snakes.Ecology : The Pelamis Platurus has been known to feed on fish, which habitat the slicks or drift lines. The slicks are formed by accumulation of foam, floating plant parts, and other debris, and this is biologically important because the plankton become concentrated in the convergence zone in the slicks, and it is good place for the zooplanktons and fish to feed, and also sea snakes since the fish tend to concentrate there, too.
Since the fish concentrate to find the food, they also seek the shelter beneath the floating debris. And Pelamis Platurus can easily mimic the debris, such as a part of the plant, by floating near the surface with less motion. Since their body color is yellow and black, it attracts the fish. Then the fish are captured by sideways movement of the head or by swimming backward, enabling the snake to capture the fish with a sudden lunge forward. And for the Pelamis Platurus, the large number of species are encountered as food items since the diversity of fish species are living in the slicks and drift lines. Studies from the Gulf of Panama in 1975 shows that the 25 fish species belonging to 19 families amongst the prey items. For Pelamis Platurus, the most common prey species are Mugilidae (mullets), Carangidae (jacks), Serranidae (anchovies), and Coryphaena (juvenile dolphin fish). The studies concluded that Pelamis Platurus feeds on any available species, with the size Pelamis Platurus can ingest.
Habitat : This species, Pelamis Platurus is the most pelagic among the sea snakes, and they occur in the open ocean well away from coasts, reefs, and shore. They are more commonly found along the drift line, the slicks are adequate for them to rest and feeding. Mainly they live in the underwater environment, however, as I mentioned above, they float near the surface of the water for the temperature control, reproduction, and spending time at the slicks.
And some small individuals (around 220mm, just after birth) are found in the Mangrove swamp, and it suggests that the Pelamis Platurus may occasionally occur intertidal habitat. They live in tropical parts of the ocean, whose temperature is around 18 – 20? since they require minimum temperature 16 – 18?. Therefore they habitat mostly around above and under the Equator, such as some countries of Africa, South America, Australia, Iran, and Vietnam, etc…
Natural History : For the snake, the fossil reminds are very low in number, therefore there is fewer fossil evidence that proves the old life of the snakes because they are very fragile and so often they are not able to preserve well. However, some were found in South America and Africa, and the oldest ones are 125 million years old. The fossil shows the evidence that the snakes evolved from aquatic lizards, such as sea serpent. The longest one was found in 49 feet long (1493.52 cm), and this is almost twice the size of the longest snakes in the world today. This means, the snakes became smaller, however, there is concentrate evidence that proves why they became smaller now.
Then the sea lizards got ashore and became the land snakes. The researchers believe that the sea snakes evolved from these land snakes, some species of elapid, not directly from the ancient sea lizards. Because the sea snakes are still all air-breathing, not branchial respiration, also some species still get ashore when they reproduce.Other : The Pelamis Platurus is venenosa, which means the snakes with venom. And the venom of them is highly toxic and it is the complex of potent neurotoxins and myotoxins. Therefore when the prey was bitten by them, the prey will be benumbed their full body and not able to move anymore. It is really strong venom, the LD50 is 0.
067mg/kg, it means they can kill 2985 of mice and 1 human for one bite (4mg of venom). However, since their fang is quite short (around ~1.5mm), and only small amount of venom is injected, the deadly accident has never occurred before.Conclusion : The yellow-bellied sea snake, the Pelamis Platurus is a unique venison (Venomous Snake) in the worldwide sea.
They adopted the sea life by changing their internal organs and outer features on the way of evolution from the sea lizards. Once they adapted to the land life, however, they returned to the sea after that. For example, for the anatomy, they changed their tails to be flattened and their scales on the abdomen became smaller to facilitate swimming more faster, and they have a single rectangular shaped huge lung (usually right lung) to make them less frequency of air respiration. And for the physiology, they got special gland to secrete excess salts, called Posterior sublingual gland, and it helps them to maintain their body health in the sea environment. They are completely aquatic, therefore they do not need to get ashore when they feed and reproduce.
And they are ovoviviparous, therefore they reproduce 1-10 living youngs after sexual mating directly in the sea. They are most widely distributed snake, therefore they habitat most of the sea whose temperature is around 18-20?, and mainly drift line and slicks where the debris and fish are concentrated.