Sea snake fangs. Sea Snakes: Venomous Marine Marvels of the Cobra Family
What are sea snakes. How many species of sea snakes exist. Where do sea snakes live. How venomous are sea snakes. What do sea snakes eat. How do sea snakes reproduce. Are sea snakes dangerous to humans.
The Fascinating World of Sea Snakes: An Overview
Sea snakes are a remarkable group of marine reptiles that have adapted to life in the oceans. These highly venomous creatures belong to the cobra family (Elapidae) and have evolved unique characteristics that allow them to thrive in aquatic environments. There are over 60 known species of sea snakes, divided into two main groups: the true sea snakes (subfamily Hydrophiinae) and the sea kraits (subfamily Laticaudinae).
True sea snakes are more closely related to Australian terrestrial elapids, while sea kraits have evolved independently. This diversity within the sea snake family showcases the incredible adaptability of these marine reptiles.
Habitat and Distribution: Where Do Sea Snakes Call Home?
Sea snakes are primarily found in the warm, tropical waters of the Indian and Pacific Oceans. Their distribution ranges from the eastern coast of Africa to the western coasts of Central and South America. Some of the most common areas where sea snakes can be encountered include:
- The coastal waters of Southeast Asia
- The Great Barrier Reef in Australia
- The Persian Gulf
- The waters surrounding many Pacific islands
Interestingly, sea snakes are absent from the Atlantic Ocean and the Caribbean Sea. This limited distribution is likely due to the geographical barriers and specific environmental requirements of these specialized marine reptiles.
Anatomical Adaptations: How Sea Snakes Thrive in Marine Environments
Sea snakes have evolved numerous adaptations that enable them to live successfully in aquatic habitats. Some of their most notable anatomical features include:
- Paddle-like tails: These flattened tails provide efficient propulsion through water.
- Valved nostrils: Special valves allow sea snakes to close their nostrils when diving.
- Salt glands: These specialized glands help sea snakes excrete excess salt from their bodies.
- Streamlined body shape: Their elongated, slender bodies reduce drag while swimming.
- Lung adaptations: Sea snakes have the ability to absorb oxygen through their skin, allowing for longer dives.
These adaptations have made sea snakes incredibly well-suited to their marine lifestyle, allowing them to dive to depths of up to 100 meters and remain submerged for extended periods.
Venom and Fangs: The Deadly Arsenal of Sea Snakes
Sea snakes are renowned for their potent venom, which is among the most toxic in the animal kingdom. Their venom is a complex mixture of proteins and neurotoxins, including:
- Erabutoxins (a, b, and c)
- Lecithinase
- Anticoagulase
- Hyaluronidase
The most active component of sea snake venom is erabutoxin b, a short-chain protein consisting of 62 amino acids. This neurotoxin acts on acetylcholine receptors, causing paralysis of skeletal muscles and potentially leading to respiratory arrest.
Sea snake fangs are relatively small and fixed at the front of the mouth. Unlike many land snakes, sea snakes do not strike quickly but tend to hold onto their prey and chew, injecting venom in the process. This behavior, combined with their generally docile nature, means that sea snake bites on humans are relatively rare.
The Rapid Biosynthesis of Sea Snake Venom
One of the most fascinating aspects of sea snake venom is its incredibly rapid biosynthesis. Experimental studies have shown that the synthesis of venom components can begin as quickly as 30 seconds after stimulation and be completed within one minute. This remarkable speed ensures that sea snakes can quickly replenish their venom supply after using it for hunting or defense.
Feeding Habits: What’s on the Menu for Sea Snakes?
Sea snakes are carnivorous predators that primarily feed on fish. Their diet can include:
- Eels
- Small reef fish
- Fish eggs
- Occasionally, crustaceans
The hunting technique of sea snakes varies depending on the species. Some actively search for prey, while others are ambush predators, lying in wait for unsuspecting fish to swim by. Their potent venom allows them to quickly immobilize their prey, making it easier to swallow whole.
Reproduction and Life Cycle: The Unique Breeding Habits of Sea Snakes
Sea snakes exhibit diverse reproductive strategies, with some notable differences between true sea snakes and sea kraits:
True Sea Snakes
Most true sea snakes are viviparous, meaning they give birth to live young. The gestation period can last several months, during which the developing embryos receive nourishment from the mother through a placenta-like structure. Litter sizes vary but typically range from 2 to 9 offspring.
Sea Kraits
Sea kraits, on the other hand, are oviparous and lay eggs. These snakes come ashore to mate and lay their eggs in rocky crevices or on beaches. After an incubation period of about two months, the young sea kraits hatch and make their way to the water.
Regardless of their reproductive method, young sea snakes are fully equipped with venom and fangs from birth, allowing them to hunt and defend themselves immediately.
Human Interactions: Are Sea Snakes a Threat to People?
Despite their highly potent venom, sea snakes are generally not considered a significant threat to humans. This is due to several factors:
- Docile nature: Most sea snakes are not aggressive and will typically avoid contact with humans.
- Reluctance to bite: Even when provoked, sea snakes often deliver “dry” bites without injecting venom.
- Small fangs: Their relatively small fangs may have difficulty penetrating thick clothing or wetsuits.
- Limited encounters: Most human activities in the ocean do not bring people into close contact with sea snakes.
However, it’s important to note that sea snake bites can be extremely dangerous if venom is injected. Symptoms of a venomous sea snake bite may include:
- Muscle pain and stiffness
- Difficulty speaking or swallowing
- Blurred vision
- Respiratory distress
In the event of a sea snake bite, immediate medical attention is crucial, as antivenin treatment may be necessary.
Conservation Status: Challenges Facing Sea Snake Populations
While many sea snake species are not currently considered threatened, some populations face significant challenges due to human activities and environmental changes. Some of the primary threats to sea snakes include:
- Habitat destruction: Coastal development and pollution can degrade important sea snake habitats.
- Climate change: Rising ocean temperatures and sea levels may impact sea snake breeding and feeding areas.
- Bycatch: Sea snakes are often accidentally caught in fishing nets, leading to injury or death.
- Targeted hunting: In some regions, sea snakes are hunted for their skin or meat.
Conservation efforts for sea snakes focus on protecting their marine habitats, reducing bycatch in fisheries, and conducting further research to better understand their ecology and population dynamics. As key components of marine ecosystems, the preservation of sea snake species is crucial for maintaining the health and balance of our oceans.
In conclusion, sea snakes represent a fascinating group of marine reptiles that have successfully adapted to life in the world’s oceans. Their unique anatomical features, potent venom, and diverse ecological roles make them a subject of great interest for researchers and nature enthusiasts alike. As we continue to explore and understand these remarkable creatures, it becomes increasingly clear that protecting sea snakes and their habitats is essential for the overall health of our marine ecosystems.
Sea Snakes
Sea Snakes
Sea
snakes come from the Family Hydrophiidae, living most or all of their lives in
usually aquatic, marine environments. They are very closely related to the
Family Elapidae which contains “cobra” type snakes, and this is most
evident in their fang structure. The right image shows the characteristic
small sized fangs towards the front of the mouth, which are used to envenom
their prey. Sea snake fangs are fixed, and unlike many land based snakes,
they do not make lightning fast strikes, instead they tend to hang on and
chew. Mmm.
Sea
snakes are typically found on tropical shores of the Pacific and Indian oceans
(luckily not the Atlantic). This close proximity to human activity means
that there have been a range of attacks recorded although the species as a whole
is not aggressive and will usually shy away. These snakes have evolved
special salivary glands that produce venom which functions to immobilise and
digest prey. Their venom is one of the most deadly in the world,
containing a lethal cocktail of proteins and neurotoxins. Sea snake venom
has been found to be 2-10 times as venomous as any terrestrial snake making them
extremely deadly, but their docile nature and relatively extreme environment
make them less dangerous than their land dwelling relatives.
Venom
The venom contains a series of proteins and
neurotoxins.
Proteins |
Neurotoxins |
lecithinase |
erabutoxin a |
anticoagulase |
erabutoxin b |
hyaluronidase |
erabutoxin c |
The neurotoxins are by far the most active
constituent of the venom and work by acting on the acetylcholine receptor.
This causes paralysis of skeletal muscle and death results by respiratory
arrest. The venom is potent, but only small amounts are usually injected
so fatalities are rare. This is coupled with an observed reluctance to
deliver venom when they bite.
Structure
The most active component of the venom is
erabutoxin b, a short chain protein that consists of 62 amino acids. The
primary structure can be illustrated as follows:
N-terminal-ARG-ILE-CYS-PHE-ASN-GLN-HIS-SER-SER-GLN-
PRO-GLN-THR-THR-LYS-THR-CYS-PRO-SER-GLY-SER-GLU-
SER-CYS-TYR-HIS-LYS-GLN-TRP-SER-ASP-PHE-ARG-GLY-
THR-ILE-ILE-GLU-ARG-GLY-CYS-GLY-CYS-PRO-THR-VAL
-LYS-PRO-GLY-ILE-LYS-LEU-SER-CYS-CYS-GLU-SER-GLU-
VAL-CYS-ASN-ASN-C-Terminal
Like so many other neurotoxins erabutoxin
b contains 4 disulfide bridges, which are known to be incredibly important in
the toxicity of the venom. The neurotoxin has an anti-parallel Beta sheet
structure containing no alpha helix structures.
Erabutoxin b
Mechanism
The mechanism that erabutoxin b exerts is not yet fully
understood but it is believed to act at acetylcholine receptors. Upon
envenomation the toxin binds to the nicotinic acetlycholine receptor on the
motor end plate blocking it irreversibly. Acetlycholine binds to an
unaffected receptor and opens an ion channel, this results in the depolarization
of the end plate through the influx of Na+ ions. If the
depolarization then causes an action potential a skeletal muscle contraction
occurs. But in the presence of erabutoxin b there is a neuromuscular
blockade between the phrenic nerve and the diaphragm. The diaphragm is
paralysed and death results from respiratory arrest.
Biosynthesis
The most amazing aspect of this toxin is its
biosynthesis, in that it is synthesized extremely quickly. The rate of
biosynthesis was experimentally found by injecting labeled isoleucine into the
venom glands. This showed the synthesis starting 30 seconds after
injection and finishing 1 minute after injection, i.e. between 30 seconds – 1
minute! For more info.
Sea snake | Types, Habitat, & Facts
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sea snake, any of more than 60 species of highly venomous marine snakes of the cobra family (Elapidae). There are two independently evolved groups: the true sea snakes (subfamily Hydrophiinae), which are related to Australian terrestrial elapids, and the sea kraits (subfamily Laticaudinae), which are related to the Asian cobras. Although their venom is the most potent of all snakes, human fatalities are rare because sea snakes are not aggressive, their venom output is small, and their fangs are very short.
Of the 55 species of true sea snakes, most adults are 1–1.5 metres (3.3–5 feet) long, though some individuals may attain 2.7 metres (8.9 feet). They are restricted to coastal areas of the Indian and western Pacific oceans, except for the yellow-bellied sea snake (Pelamis platurus), found in open ocean from Africa eastward across the Pacific to the west coast of the Americas. All other species live mainly in waters less than 30 metres (about 100 feet) deep, as they must dive to the seafloor to obtain their food among coral reefs, among mangroves, or on the ocean bottom. Some species prefer hard bottoms (corals), while others prefer soft bottoms (mud or sand) in which to hunt their prey. Most sea snakes feed upon fishes of various sizes and shapes, including eels. Two primitive groups (genera Aipysurus and Emydocephalus) eat only fish eggs; Hydrophis specializes in burrowing eels.
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In adaptation to marine life, true sea snakes have a flattened body with a short oarlike tail, valvular nostrils on top of the snout, and elongated lungs that extend the entire length of the body. Their scales are very small and usually not overlapping (juxtaposed), abutting against one another like paving stones. The belly scales are reduced in size in the primitive species, whereas in the more advanced forms they are absent. As a result, the advanced species cannot crawl and are thus helpless on land. When swimming, a keel is formed along part of the belly, increasing surface area and aiding propulsion, which occurs by lateral undulation. Sea snakes can remain submerged for several hours, possibly as much as eight or more. This remarkable feat is partly due to the fact that they can breathe through their skin. More than 90 percent of waste carbon dioxide and 33 percent of their oxygen requirement can be transported via cutaneous respiration. Moreover, a 2019 study of the blue-banded sea snake (or annulated sea snake, Hydrophis cyanocinctus) found a highly vascularized area between the snout and the top of the head, which allows oxygen to be transported directly from the water to the snake’s brain. Sea snakes give birth in the ocean to an average of 2–9 young, but as many as 34 may be born. The 54 species in subfamily Hydrophiinae belong to 16 different genera.
The six species of sea kraits (genus Laticauda) are not as specialized for aquatic life as the true sea snakes. Although the tail is flattened, the body is cylindrical, and the nostrils are lateral. They have enlarged belly scales like those of terrestrial snakes and can crawl and climb on land. The typical colour pattern consists of alternating bands of black with gray, blue, or white rings. The yellow-lipped sea krait (L. colubrina) is a common species that possesses this pattern and has a yellow snout. Sea kraits are nocturnal, feeding primarily on eels at depths of less than 15 metres (49 feet). They go ashore to lay their eggs, climbing up into limestone caves and rock crevices, where they deposit 1–10 eggs. Adults average 1 metre in length, but some grow to more than 1.5 metres. The longevity record in captivity is seven years.
The Editors of Encyclopaedia Britannica
This article was most recently revised and updated by John P. Rafferty.
Crown of Evolution. Scientists have figured out how venomous snakes got their famous fangs.
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In a new study, scientists show that the changes occurred due to modifications in the structure of the teeth, which helped to fix the fangs in the sockets. In some species of snakes, channels have developed in the teeth that run through the entire canine tooth, which began to be used to inject poison, reports theconversation. com
Of the nearly 4,000 snake species, about 600 are considered medically dangerous. This means that after a bite, a person needs urgent medical attention. But many of these snakes have small fangs and are considered not very venomous. According to scientists, the appearance of not very dangerous poisons precedes the appearance of poisonous fangs in snakes.
Taipan
Photo: wikipedia
Venomous fangs of snakes vary:
- They can be placed in the back of the mouth, as in crab-eating water snakes, cat-eyes, gray tree snakes and boomslangs
- They can be placed in the front of the mouth, like in cobras, coral snakes, kraits, taipans and sea snakes
- They may also be in the front of the mouth, but may curve backwards or sideways, as in vipers and rattlesnakes.
Location of poisonous fangs in snakes
Photo: The Conversation
The History of Fangs
“If you look at the evolution of snakes, the most recent common ancestor of all snakes with fangs probably didn’t have them,” said study authors Alessandro Palchi of Flinders University, Australia, Aaron LeBlanc of King’s College London and Olga Panagiotopoulou of Monash University, Australia.
So how did snakes evolve their syringe-like fangs that evolved from the simpler, cone-shaped teeth of their ancestors?
“To answer this question, we carefully studied snake teeth and how they develop. We examined 19 species of snakes, both venomous and common, as well as one fossil snake,” the scientists say.
Taipan skull and close-up of its left canine, in longitudinal and transverse sections, showing the relationship between the plicidentin folds and the venom channel.
Photo: The Conversation
The secret of snake teeth
“We found that almost all snakes have teeth that are strongly concave at the base and look wrinkled in cross section,” scientists say.
These folds, plicidentins, occur in the layer of the tooth called dentin. Plicidentins have been found in many extinct animals and in some species of extant fish and lizards, but their purpose is not fully understood. One theory suggests that they help the tooth not break during biting.
“When we tested this theory with computer simulations, we found that it was not,” the study authors say.
Snakes change their teeth throughout their lives and their teeth are placed in shallow holes. Scientists believe that these folds improve the anchoring of new teeth in empty sockets, providing a larger area for attachment.
Scientists say that one of the folds in poisonous snakes is much larger than the others. It occupies the entire tooth, forming a channel for the passage of poison. The researchers also found that in some species of venomous snakes, such channels may exist in teeth other than fangs, but they are not associated with venom glands.
“We found a clear relationship between the presence of plicidentins and venom channels. We concluded that at the very beginning, venomous snakes accidentally developed canals in their teeth, simply as a result of an increase in plicidentins, independent of the venom glands,” the scientists say.
Cobra
Photo: wikipedia
How ordinary teeth became venomous
The scientists then investigated how snake fangs and venom glands evolved together to become an effective means of delivering venom. In the ancestors of modern venomous snakes, the presence of venom glands was a necessary condition for the transformation of teeth with channels into enlarged venomous fangs.
Scientists believe that when a tooth appeared with a canal near the exit of the poisonous gland, natural selection contributed to the increase in this tooth in size. Also, this tooth has become more effective at injecting poison.
“This evolutionary process eventually led to the large, syringe-shaped fangs that venomous snakes have today,” the scientists say.
Poisonous snakes. Questions and Answers
There are more than 2500 species of snakes in the world. Of these, only 450 species are poisonous. These include vipers, cobras, mambas, sea snakes, etc. Even poisonous snakes only attack for defense.
Why do snakes have fangs?
With the help of fangs, snakes inject poison into the victim’s body. All venomous snakes have venom glands next to their fangs. When the snake bites the prey, the muscles press on the gland, the poison passes through the hollow fangs and is injected into the body of the victim.
The viper, one of the most venomous snakes, has only one pair of fangs. But they are longer than other types of snakes
Why do cobras have shorter fangs than vipers?
Cobras and other snakes of the same family have short fangs. Unlike vipers, these snakes cannot put their teeth in their mouths when they are not using them. If the fangs were too long, the cobra would injure itself by closing its mouth.
How many types of venom do snakes produce?
There are two types of snake venoms. Asps produce neurotoxins. They affect the nervous system of the victim and lead to rapid death. Vipers produce a hemotoxin that affects the blood and organs, but does not kill immediately.
What is the difference between a pit viper and a true viper?
Both snakes belong to the same family. However, pit vipers (rattlesnakes) have special heat-sensitive organs – pits located between the ears and nostrils. These organs allow snakes to sense temperature differences between prey and surroundings, so rattlesnakes can hunt even in the dark.
The rattle of the pit viper consists of modified scales at the end of the tail. Each time a rattlesnake changes skin, a new segment is added to the rattle.
Are rattlesnakes venomous?
Rattlesnakes are very poisonous. They are found in North America and Mexico. Most species produce a very potent hemotoxic venom. Usually snakes warn of an attack by twitching their tail, which has a rattle of several connected scaly segments. When the snake twitches its tail, the segments rub against each other and make a crackling sound that repels most animals.
How have sea snakes adapted to life in the water?
Sea snakes have a paddle-shaped tail. They have a large lung that fills almost the entire body. Because of this, snakes can stay under water for a long time. Sea snakes prey on fish and small marine animals.
Sea snakes are found in warm waters, mainly off the coast of Asia and South America. Compared to other snakes, they have flatter heads, which helps them swim better
Which snake has the longest fangs?
The Gaboon viper has the longest fangs, their length can reach 5 cm.
What is the most poisonous snake in the world?
The most venomous snake living on land is the taipan, which lives in Australia. Taipan venom is 400 times stronger than rattlesnake venom. However, more people die from cobra bites because cobras are found in more densely populated areas.