How do sea snakes differ from land snakes. What makes sea snake venom so potent. Where are sea snakes typically found. How do sea snakes breathe underwater. What adaptations allow sea snakes to thrive in marine environments. Why are sea snake bites relatively rare despite their powerful venom. How quickly can sea snakes produce venom.

The Intriguing World of Sea Snakes: An Overview

Sea snakes, belonging to the family Hydrophiidae, are a group of fascinating marine reptiles that have adapted to life in aquatic environments. These remarkable creatures are closely related to the Elapidae family, which includes cobras, and share similar fang structures. Unlike their terrestrial counterparts, sea snakes have evolved unique features that allow them to thrive in oceanic habitats.

Most sea snake species spend their entire lives in marine environments, with some venturing into brackish waters. Their distribution is primarily limited to the tropical shores of the Pacific and Indian oceans, notably absent from the Atlantic. This geographic restriction has implications for human interactions and potential encounters with these intriguing reptiles.

Key Characteristics of Sea Snakes

• Flattened, oar-like tail for efficient swimming
• Salt glands to expel excess salt from their bodies
• Nostrils located at the top of their snouts for surface breathing
• Fixed, front-positioned fangs for venom delivery
• Highly potent venom composed of proteins and neurotoxins

Sea Snake Venom: A Lethal Cocktail

One of the most intriguing aspects of sea snakes is their incredibly potent venom. How does sea snake venom compare to that of terrestrial snakes? Studies have shown that sea snake venom can be 2-10 times more potent than that of their land-dwelling relatives, making it one of the deadliest in the world.

The venom of sea snakes is a complex mixture of proteins and neurotoxins, each playing a specific role in subduing prey and aiding in digestion. Some of the key components include:

Proteins in Sea Snake Venom

• Lecithinase
• Anticoagulase
• Hyaluronidase

Neurotoxins in Sea Snake Venom

• Erabutoxin a
• Erabutoxin b
• Erabutoxin c

Among these components, erabutoxin b stands out as the most active constituent of sea snake venom. This short-chain protein, consisting of 62 amino acids, plays a crucial role in the venom’s potency and mechanism of action.

Erabutoxin b: The Deadly Neurotoxin

Erabutoxin b, the primary neurotoxin in sea snake venom, has a fascinating structure and mechanism of action. This protein contains 4 disulfide bridges, which are critical for its toxicity. The neurotoxin adopts an anti-parallel beta-sheet structure, lacking any alpha-helix formations.

How does erabutoxin b cause paralysis in its victims? The mechanism, while not fully understood, is believed to involve the acetylcholine receptors. Upon envenomation, erabutoxin b binds irreversibly to the nicotinic acetylcholine receptors on motor end plates. This binding blocks the normal function of these receptors, leading to a neuromuscular blockade between the phrenic nerve and the diaphragm. Consequently, the diaphragm becomes paralyzed, resulting in respiratory arrest and, ultimately, death.

The Remarkable Biosynthesis of Sea Snake Venom

Perhaps one of the most astonishing aspects of sea snake venom is the speed at which it is produced. How quickly can sea snakes synthesize their venom? Experimental studies using labeled isoleucine injected into venom glands have revealed an incredibly rapid biosynthesis process.

The synthesis of sea snake venom components begins a mere 30 seconds after the injection of precursor molecules and completes within 1 minute. This remarkably fast production rate ensures that sea snakes can quickly replenish their venom supply, allowing them to defend themselves or capture prey efficiently.

Sea Snake Adaptations for Marine Life

Sea snakes have evolved numerous adaptations that enable them to thrive in marine environments. These adaptations set them apart from their terrestrial counterparts and contribute to their success as aquatic predators.

Physical Adaptations

• Flattened, paddle-like tail for enhanced swimming ability
• Streamlined body shape to reduce drag in water
• Valved nostrils that close underwater
• Scales that overlap tightly to prevent water infiltration

Physiological Adaptations

• Salt glands near the tongue to excrete excess salt
• Ability to absorb oxygen through the skin while underwater
• Enhanced lung capacity for prolonged dives
• Slower heart rate and reduced blood flow to conserve oxygen during dives

These adaptations allow sea snakes to remain submerged for extended periods, typically up to 30 minutes, with some species capable of staying underwater for up to two hours. How do sea snakes breathe underwater? While they primarily rely on surfacing to breathe air, their ability to absorb oxygen through their skin contributes to their underwater endurance.

Sea Snake Behavior and Ecology

Despite their potent venom, sea snakes are generally not aggressive towards humans. Their docile nature, combined with their preference for marine habitats, makes encounters with humans relatively rare. However, their proximity to tropical shores means that interactions do occur, particularly with fishermen and divers.

Sea snakes primarily feed on fish, eels, and occasionally crustaceans. Their hunting technique differs from that of many terrestrial snakes. Instead of striking quickly, sea snakes tend to grab their prey and hold on, using their venom to immobilize the victim. This method is well-suited to their aquatic environment, where swift strikes might be less effective.

Reproduction and Life Cycle

Most sea snake species are viviparous, giving birth to live young in the water. The gestation period varies among species but typically ranges from 4 to 11 months. Litter sizes are generally small, with most species producing 2 to 9 offspring per breeding cycle.

Young sea snakes are born fully developed and capable of swimming and hunting immediately. They reach sexual maturity at around 2 to 3 years of age, with lifespans in the wild estimated to be between 10 to 15 years for most species.

Conservation Status and Threats

While sea snakes are not currently considered globally threatened, several species face localized threats. The primary challenges to sea snake populations include:

• Habitat destruction, particularly of coral reefs
• Bycatch in fishing operations
• Climate change affecting ocean temperatures and prey availability
• Pollution, especially plastic waste in marine environments

Conservation efforts for sea snakes focus on protecting their marine habitats, implementing sustainable fishing practices to reduce bycatch, and conducting further research to better understand their ecology and population dynamics.

Sea Snakes in Human Culture and Medicine

Throughout history, sea snakes have played various roles in human culture, particularly in coastal communities where they are frequently encountered. In some regions, they are feared for their potent venom, while in others, they are revered or used for traditional medicine.

The potential medical applications of sea snake venom are an area of ongoing research. Some studies have explored the use of sea snake venom components in the development of pain medications and treatments for neurodegenerative diseases. However, much work remains to be done to fully understand and harness the potential therapeutic benefits of these fascinating creatures.

In conclusion, sea snakes represent a remarkable example of evolutionary adaptation to marine life. Their unique physical and physiological characteristics, combined with their potent venom, make them a subject of great interest to researchers and nature enthusiasts alike. As we continue to study these intriguing reptiles, we gain valuable insights into the diversity and resilience of life in our oceans, as well as potential applications for human health and medicine.

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.

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 Snakes Facts and Information

Scientific Classification

Common Name

sea snakes

Kingdom

Animalia

Phylum

Chordata

Class

Reptilia

Order

Squamata

Family

Hydrophiidae (“water lovers”)

Genus Species

Approximately 52 species

Fast Facts

Description

Sea snakes can be identified by their flattened and oar-like tail. This adaptation allows sea snakes to propel themselves through the water more effectively. Other aquatic adaptations include salt glands and nostrils located at the top of their snouts to breathe more efficiently.

Size

They vary in length, with the smallest adults being 50 cm (20 in.) long, to the largest, which may exceed 2 m (6.6 ft.).

Weight

No data

Diet

Sea snakes feed mainly on fishes and fish eggs.

Incubation

Sea snakes can be oviparous (egg birth) or ovoviviparous (egg live birth), depending on the species. In ovoviviparous reproduction, the internally fertilized eggs of the female are retained in her body. The embryos soon shed their membrane and develop in the mother’s uterus

Clutch Size: Sea snakes usually have 3-4 young at a time.

Sexual Maturity

No data

Life Span

No data

Range

Sea snakes are widely distributed throughout the Indian and Pacific oceans, especially around Australia and New Guinea. Two species, Laticauda colubrina and Pelamis laturus, inhabit the coasts of the Americas.

Habitat

Found in shallow or coastal water habitats. Some species may venture on land, although most sea snakes are helpless if washed ashore.

Population

Global: No data

Status 

IUCN: One species, Crocker’s sea snake, Laticauda crockeri, is listed as vulnerable.
CITES: Not listed
USFWS: Not listed

Fun Facts

1. Sea snakes are front-fanged and highly venomous.
2. A fold in the gums of a sea snake hides the fangs, and the fangs quickly emerge when biting. Sea snake fangs are fragile and may break off and remain in the wounds of their victims. To counter the problem of having weak fangs, sea snakes have potent venom that can easily paralyze, kill, and begin the digestive process of the fish they target.

Ecology and Conservation

Generally, sea snakes are not aggressive animals – attacks on humans are extremely rare. Bites occur chiefly to fishermen who try to remove sea snakes from their nets. Also, sea snakes will defend themselves if seized or harassed.

Sea snakes are regarded as a delicacy in the Orient. Sea snakes are attracted by light, which is often the method used by humans to collect them.

Bibliography

Bauchot, Roland (ed.). Snakes a Natural History. New York: Sterling Publishing Co., Inc., 1994.

Coborn, John. The Atlas of Snakes of the World. New Jersey: T.F.H. Publications, inc. 1991.

Cogger, H.G. and R. G. Zweifel. The Encyclopedia of Reptiles and Amphibians, 2nd ed. San Diego. Academic Press. 1998.

Ernst, Carl H., and Zug, George R. Snakes in Question. Washington: Smithsonian Institution Press, 1996.

Mattison, Chris. Snakes of the World. New York: Facts on File Publications, Inc., 1986.

Mehrtens, John M. Living Snakes of the World. New York. Sterling Publishing Co., Inc. 1987.

animaldiversity.ummz.umich.edu

Crown of Evolution.

Scientists have figured out how venomous snakes got their famous fangs.

Related video

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.