Sea Snakes Elisse Tallerico
Abstract Morphology Feeding
Sea snakes are an awe worthy and beautiful element to the Earth’s oceans. Some Sea snakes, like terrestrial snakes, are scaled reptilians with no limbs or Most sea snakes will eat a variety of fish, eels, crabs and other invertebrates. are partially terrestrial while others are entirely marine. They share many traits internal girdles. However, while terrestrial snakes have enlarged ventral scales to Those that are partly terrestrial sometimes enjoy an even more diverse menu. with their fully terrestrial cousins and possess some interesting adaptations to aid in moving across the ground, sea snakes have no need for this adaptation. Their Some are specialized eaters like the eel eaters (Hydrophiidae family) or strict fish their life in the water. It is believed that there are 70 species of sea snakes (this ventral scales are, normally, the same size as their dorsal scales. The scales egg eaters (Aipysurus eydouxii and the turtle headed sea snakes). Sea snakes number includes fresh water snakes that occasionally enter marine habitats). Of surrounding the mouth fit tightly together to prevent sea water intrusion (except mostly use their sense of smell and sense of vibrations to detect prey. They do not these 70 species, they are broken into four families Hydrophiidae, Laticudidae, for an opening for the tongue). The anal scales extend backward to seal the vent for seem to use their eye sight as a tool for hunting. To hunt, sea snakes employ a few Archorchodidae and Colubridae. These animals range from non-venomous to the same reason. Another adaptation to prevent sea water intrusion are little flaps different techniques, depending on target prey. A technique used by many snakes mildly venomous to highly venomous, depending on the species. Those that are of tissue that engorge with blood and effectively seal the snake’s nostrils. Despite is called crevice foraging. This is where the snake actively pokes through cracks in venomous are believed to be descended from terrestrial cobras. Different all these adaptations, salt does make its way into the body, and the snake needs a species have evolved different hunting techniques and ways to produce young. rocks, reefs and other structures to find prey. They have been seen targeting prey They only inhabit tropic and sub tropic waters and rarely travel far distances due way to expel the excess. Most snakes (ones that are strictly marine and spent most in a crevice, wrap their body around the opening to prevent escape and attack to their cold blooded nature. their time in water) possess an excretory gland in their mouth. This gland is a their prey (fairly clever for a reptile). Another method is called cruising. This is modified salivary gland, known as the sublingual gland, which excretes excess salt. where they swim along and strike, laterally at a fish who is not paying attention. Though the snake’s body is highly adapted to keep sea water out, they are able to This method does not generally work on fast moving or far off prey as the snake is respire through their skin to a degree. The ability to breath under water depends not able to quickly pursue a fast prey item. The ambush method has only been Hydrophis elegans (Mazza) on the species but some are able to absorb 1/5 of their required O2 through the known to be used by the yellow bellied sea snake. The snake floats as still as skin. This adaption is one of the reasons some species are able to stay submerged possible, trying to imitate a fallen branch and waits for fish to come to it. Once a for, up to, two hours. Some have even been recorded to dive at a depth of 100m fish comes close enough, the snake is able to strike and eat its prey. (Heatwole, (though this is uncommon, as most prefer shallow water). A unique adaptation for Yellow Belly Sea Snake ambush hunting (Nelson) 1987) sea snakes is that they have a singular, tubed lung instead of two branched lungs. Breeding and Migration Eating with no limbs or chewing teeth is difficult enough, doing so in the water Most sea snakes range from 60 to 80cm long, though some species have been It has not been studied in great depth, but sea snakes do not appear to travel a is even trickier. Once a snake has caught a prey item, he will face the current and recorded to reach an excess of 200cm (Hydrophis elegens and Hydrophis spiralis). significant distance in order to mate. Most sea snakes do not travel any further then turn his head toward the anterior end of his body. This way the current These animals are highly adapted to their marine environment. Many species than 200m out of their original habitat (those that have been found that far assists in keeping the prey item aligned during swallowing. The snake has to bodies have a slight lateral compression and their heads are not greatly defined were carried by a current). Their territories tend to greatly overlap, and they swallow his prey head first to avoid damage to his own body. A sea snake will from the body. Certain species also have a notably flattened tail that resembles a do not appear to be territorial. The only ‘migrating’ that happens is movement carefully chew along the body, turning it until the head is positioned in his mouth. paddle, especially ones that live in more current heavy habitats. This flattened tail to a nearby area that is slightly sheltered and has calmer water (like an estuary) Once this is accomplished he may swallow his prey. assists in propulsion through the water, some species’ tails are even light sensitive. when breeding or giving birth. Sea snakes have not evolved the ability to drink Regardless of body shape and size, all sea snakes move through the water with a sea water, they must drink fresh water to survive. Some sea snakes that have lateral undulating movement. Sea snakes color ranges from muddy brown Most sea snakes mate in the water. Males terrestrial abilities can go on land to find rain water that has collected in pools or in (Aipysurus apraefrontalis) to a striking combination of black and yellow (Pelamis have copulatory organs known as hemipenes. They have two, but only one is leaves. This is not so easy for the snakes that do not leave the ocean. They may Venom platurus). (Heatwole, 1987) used at a time. Once copulation has begun, the male is stuck to the female and cannot disengage until mating is finished. He is subject to the female’s have to wait months at a time for a drink of water. When it rains on the open Almost all sea snakes, to a degree, are venomous (with the exception of swimming pattern, so when she surfaces to breath he has to attempt to get ocean, a lens of fresh water will float on top of the sea water for a short period of acrochordids and natricines). Inside the snakes head, they possess venom glands. Sea Snake distribution (Stammler) some breaths of air too. Mating cycles depend on location, not species. For time. This is where strict marine snakes obtain fresh water for drinking. Some These are elongated, specialized salivary organs located behind the eyes. There example, a species that lives in the Philippines might be strictly seasonal but snakes will only drink a few sips of water while others have been recorded to drink are two parts to the gland. The anterior region is the accessory part and secretes a the same species living in Malacca are seasonal. up to 25% of their body weight. Due to droughts, there has been less rain fall in mucus made of polysaccharides to aid in substance flow. The posterior section is recent years. This has caused a decline in sea snakes because they are dying of the region that manufactures the toxic proteins and polypeptides. Sea snakes do Female sea snakes can be either viviparous dehydration. (Lillywhite, 2014) not possess the impressive swinging fangs that are familiar in land vipers. Rather, or oviparous. Those that are viviparous will give birth in the water and those sea snakes have short cone shaped fangs that are either hollow or solid and that are egg laying will do so on land. Oviparous snakes carry their eggs higher grooved (depending on species). Some sea snakes even have their fangs located in the body than terrestrial snakes so that it does not greatly impair their toward the rear of their mouth. Most sea snakes possess a combination of swimming ability. The amount of time the eggs/young stay within the mother’s different toxins. These toxins fall into the categories of nephrotoxins, mycotoxins, body depends on the species. However, overall incubation period for sea Works Cited hemotoxins and neurotoxins. The type of toxin depends on the species of snake snakes is significantly longer than terrestrial snakes (three to four months as (and their target prey). Some sea snakes have so little toxin that it would do opposed to nine months). Most females will produce 10 -15 young depending nothing more to a man than cause slight redness and irritation of the skin while on species. Some species will produce clutches of less than five (most Dusheck, Jennie. Annoying Anemones Shed Light on Coral Reef Biology. Scope, Stanford. 1 Sep 2015. others have enough venom to kill 50 men. Why does a sea snake need such potent hydrophiids and laticaudids). The ‘reproductive effort’ spent on natal sea Web. 3 Dec 2015 venom? There are two answers. Firstly, some target prey of certain sea snake snakes is greater than terrestrial ones (more of the mother’s resources go to Heatwole, Harold. Sea Snakes. Malabar. Kreiger Publishing Company. 1987. Print species, have developed a tolerance to sea snake venom ( The same fish may be producing the young). Mortality rate of young sea snakes is very high. Only 10- tolerant to one snake species while susceptible to a snake not normally found in 20% of newborns survive their first year, and only 6% of females survive long Heithaus, Mike. Shark Bay Ecosystem Research Project. Florida International University. Web. 30 Nov the environment), which caused the snake to develop more and more potent enough to breed. (Heatwole, 1987) 2015. venom over generations. Secondly is for safety and digestion. Eating a struggling Lillywhite, Harvey and Spence, Cindy. Sea Snakes Need Freshwater for Drinking, Researcher Finds. Sea Snake Crevice Hunting (animalstime.com) animal when you have no limbs can be tricky and dangerous. Some sea snakes University of Florida News. 19 Nov 2015. Web. 28 Dec 2015. have developed a toxin to quickly dispatch their prey and allow easier consumption (neurotoxins and nepthrotoxins). It is also quite hard to digest prey if you are not Mazza, Guiseppe. Dr. Guiseppe Mazza. Photo Mazza. Web. 3 Dec 2015. able to masticate it first (in most animals this allows saliva to thoroughly work into the food matter and break it down for digestion). This is where mycotoxins come Environment in handy. Mycotoxins quickly break down muscle tissue, aiding in the snake’s All marine snakes inhabit tropic and sub tropic waters. The most varied and Nelson, Kerry. Are There Any Countries Without Snakes? Life is Short but Snakes are Long. 30 Oct digestion. (Heatwole, 1987)) diversified populations are found in the water of northern Australia, Malaysia and 2015. Web. 3 Dec 2015. Luckily for us, sea snakes are not, in general, aggressive. There are some species Indonesia. As you travel toward the Pacific, variation in species decreases. Most Stammler, Lukas. General Information on Sea Snakes. VAPA Guide. 2011. Web. 3 Dec 2015. that refuse to strike despite heavy harassment (Laticuada family). Others will only sea snakes prefer shallow waters close to some kind of land or reef mass, but some have been found in deeper water. Usually if a snake is found in open water, it is strike after heavy harassment. Most bites occur after such interaction. There are a **Picture downloaded from
RESEARCH POSTER PRESENTATION DESIGN © 2015 valida) while others will not leave the ocean willingly (Bitia hydroides and Cantoria The bestwww.PosterPresentations.com advice a swimmer or diver can take is to remember you are in their territory, so give them the respect and space they deserve. violcea to name a couple). (Heithaus)