Animals that Start with E - Listed With Pictures, Facts

Gypsy Touch To Combat Snake-bite

Gypsy touch to combat snake-biteBy Kumudini HettiarachchiIf you see a snake, don't kill it. Call the Colombo Medical Faculty for they are looking out for those creepy-crawlies in a novel project not only to help the thousands of snake-bite victims of Sri Lanka but also to protect these reptiles.

Seven deadly snakesThe seven venomous snakes found in Sri Lanka are the Russell's Viper (thith polonga), Saw-scaled Viper (weli polonga), Hump-nosed Viper (kuna katuwa or polon thelissa), Cobra (nagaya), Common Krait (thel karawala), Ceylon Krait (magamaruwa) and Green-pit Viper (pala polonga).

Symptoms and signs of a snake-bite would depend on the amount of venom that the victim has in the blood and what type of snake has bitten him. Symptoms include bleeding, non-clotting of blood, neurological problems, respiratory problems and renal failure.

What should be done? The victim should be taken to the closest hospital immediately. First aid at the spot should be to wash the bite area with soap and water or wipe with a clean cloth. The victim should not be allowed to walk or do anything vigorous as movement quickens the spread of the venom through the blood circulation.

The Faculty of Medicine, University of Colombo, 25, Kynsey Road, Colombo 7 (Phone: 695300 Ext. 318 or Ext. 608 or 695351; Off-hours 508200) could be contacted to catch the snake.

The project is novel because it will mix the expertise of widely varying groups - the earthy common sense of the humble ahukuntika clan from the outbacks of Kudagama, off Tambuttegama and the scientific knowledge of the Department of Clinical Medicine under the guidance of Prof. Rezvi Sheriff in Colombo and the University of Oxford across the seas in England.

Already a Snake Venom Research Laboratory has been set up and the Department of Clinical Medicine is working closely with wildlife officials to start a herpetarium, to meet a long felt need. A need acutely and sometimes tragically felt by snake-bite victims. In 2000, there were 48,000 reported incidents of snake-bite, with 194 deaths in the country, but the figure could be higher as some cases go unreported. Ironically, Sri Lanka which is quite well-known for its poisonous snakes, with some ancient records even indicating the existence of anacondas those days, has so far had no means of producing its own anti-venom serum. "The treatment for poisonous snake-bite, is to inject anti-venom serum to neutralize the venom in the blood. But we don't have proper anti-venom for indigenous snakes because we have been importing all requirements of the serum from India. That is not suitable, as even within Sri Lanka there are geographical variations, for example, the Russell's Viper's," explains Dr. Ariyarani Ariyaratnam of the Department of Clinical Medicine.

The serum, which the country has been importing for over 50 years is not specific for local snakes and could also have adverse reactions such as fever, chills and rigours, respiratory difficulties and blood pressure drops in patients which could sometimes even be fatal. In 1985, the Health Ministry and the Oxford University conducted research in Anuradhapura and lab tests with the imported antivenom and found that it didn't fully clear the blood of victims of the venom.

"The need for our own anti-venom became acute," says Dr. Ariyaratnam.

By 1995, the Medical Faculty made a start in this direction by sending live local snakes to Liverpool University. There they were milked and the venom provided to a company to produce the anti-venom serum that was specifically required for the treatment of Sri Lankan patients. The anti-venom was then used for clinical trial studies in Anuradhapura conducted by the Oxford-Colombo Snake Bite Research Group under Prof. Sheriff and Prof. David Warrel of Oxford.

Conceding that this was a costly method and considering the large number of victims of snake bite, the Medical Faculty has taken another step to set up its own research lab and herpetarium. They will then keep the snakes there, milk the venom, freeze it and send it abroad, maybe to a country close by such as India for 'custom-made' serum for Sri Lanka.

That's where the gypsies come in, for what better snake-catchers are there? The Medical Faculty has already made contact with the gypsy community living in Kudagama, just off the Tambuttegama-Kurunegala Road, a path we traversed on a lazy Sunday. Tall grass lines the red, gravel road and brick houses gradually give way to thatched cottages. There is a hint of rain as we go in search of the Arachchi of Kudagama.

A youth with curly black hair and sparkling eyes cycling furiously along the road, becomes our guide, for he happens to be the Arachchi's nephew. Suddenly we come upon the colony. Dogs, cats, hens and piglets roam the tiny plots of land around the neatly-thatched wattle and daub homes of the gypsies.

A baby is fast asleep in a 'saree cradle' hung from the branch of a tree. Young children and girls loiter around curious to find out our business. We are on a strange mission. To talk to the gypsies about their expertise on snakes. Theirs is the down-to-earth indigenous knowledge of people living off the land. For them the snake represents their livelihood. They catch them, pull out their fangs and use the reptiles for 'dancing and charming' or to put around tourists' necks to earn a few rupees for their daily rice and curry. Michael, the Arachchi smiles warmly showing us his red betel-stained teeth. His nephew has already told him our business. Yes, they are snake charmers and know how to handle snakes. In their free time they cultivate the land to make ends meet. That day most of his relatives had gone to the cities with their small entourage of snakes, monkeys and women who say 'saasthare'.

"Colombo people have asked for our help and we'll assist them," says Michael, explaining that they catch snakes such as the polonga, nagaya and pimbura in wela areas in Polgahawela. "We catch them by the tail and keep a stick to their heads and then pull out the fangs with a small knife. The fangs need to be removed once a week. When the fangs are pulled out, the venom comes out like frothy soap."

The Medical Faculty has other ideas on how to treat the snakes. "We will not harm them or remove their fangs. We plan to milk the venom without harming or injuring the snakes. We will look after the snakes and feed them," says Dr. Ariyaratnam.

Snakes are the bane of the poor rural folk in areas such as Anuradhapura, Polonnaruwa, Kurunegala and Vavuniya. The Common Krait bites people while they are sleeping on the floor and other folk get bitten while working in the fields.

But cities too are not free of these reptiles, with Colombo reporting Hump-nosed Viper bites. With plans afoot to make our own anti-venom eventually, there is hope that the number of deaths from snake-bite could be cut down drastically in Sri Lanka.

Snakebites: We Thought We'd Created A Winning New Antivenom But Then It Flopped. Why That Turned Out To Be A Good Thing

by Christoffer Vinther Sørensen, Andreas Hougaard Laustsen, Bruno Lomonte and Julián Fernández, The Conversation

Snakebites kill over 100,000 people each year, and hundreds of thousands of survivors are left with long-term disabilities such as amputations.

Africa, Asia and Latin America are the regions most heavily affected. The most venomous snakes in Africa are the black mamba, cobras and saw-scaled and carpet vipers. In Asia, the Indian cobra, Russel's viper, saw-scaled viper and common krait are the most venomous.

In the Central America and northern South America regions, the venomous pit viper Bothrops asper is responsible for most of the fatal and harmful bites.

We are venom and antivenom specialists who spent four years developing a therapeutic antibody to mitigate the effects of the pit viper's bites. We were certain that we'd met all the standards for an effective, safe and efficacious antivenom. But, at the last hurdle, we realized the antibody didn't neutralize the snake's toxins: it enhanced them, worsening the venom's effects.

Initially this was, of course, very disappointing. But it was also a valuable lesson. By reporting this new way that future antivenoms can fail, we have highlighted a problem with the current recommendations for testing antivenoms that was hidden until now.

Our lesson is likely to have a much larger impact on the development of snakebite treatments than if the antibody had been a success, because the discovery will help antivenom researchers focus their efforts so they don't fail at the last hurdle as we did.

Developing our antivenom

A large percentage of B. Asper's venom consists of potent muscle-damaging molecules called phospholipases A₂ (PLA₂s) and PLA₂-like toxins. These have severe effects, often leading to irreversible damage and disability.

Myotoxin II, a formidable PLA₂-like toxin within B. Asper's arsenal, is particularly significant. The precise mechanisms that underlie myotoxin II's action aren't fully understood. It is known to exert its effects locally, binding to muscle fibers and triggering muscle damage. This localized action poses a challenge for traditional antivenom treatments.

We have attempted to develop human monoclonal antibodies that target and neutralize this membrane-disrupting myotoxin II. For the first four years of our research project, the antibodies we discovered kept showing impressive effects in neutralizing myotoxin II.

Even when tested in living mice, using the current gold standard for antivenom testing, the antibodies continuously showed impressive neutralization. However, for our most promising antibody, we wanted to go a step further and carry out an experiment that more closely resembled a human envenoming, in which the antibody is injected after injection of the venom.

The results of this additional experiment were equal parts disappointing and surprising. Our most promising antibody in this last experiment changed its toxin-neutralizing effect to toxin-enhancing instead, as we've documented in a research paper.

The results were so surprising that we decided to immediately repeat the experiment. We thought something must've gone wrong, like the antibody or other materials having gone bad. However, the results remained the same.

This curious phenomenon, which we termed "antibody-dependent enhancement of toxicity", represents a novel discovery in toxin immunology. Similar phenomena have been observed in other contexts, such as with poisonous mushrooms and bacterial toxins, but never before with toxins from the animal kingdom.

Additional studies will be needed to fully understand what causes antibody-dependent enhancement of toxicity.

Reassessing preclinical models

There's good news about this failure. It's a chance for antivenom researchers all over the world, no matter what snake species they're working with, to reassess their preclinical models (like the current gold standard model).

We also think antivenom researchers should consider incorporating more sophisticated experiments like the ones used in our study, which more closely resemble a real-life envenoming case. By doing so, the antivenom research community can streamline the drug discovery process. This will expedite the identification and development of safer and more effective snakebite treatments.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Citation: Snakebites: We thought we'd created a winning new antivenom but then it flopped. Why that turned out to be a good thing (2024, March 18) retrieved 9 April 2024 from https://phys.Org/news/2024-03-snakebites-thought-antivenom-flopped-good.Html

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A Deep Dive Into Sea Snakes, Sea Kraits And Their Aquatic Adaptations

Sea snakes are best known for their potent venom and startling colour schemes, leaving some impressive features overlooked.

From nostrils that act as valves to tails and even scales that ease movement through the waves, these marine reptiles are very well adapted to aquatic life.

What is a sea snake?

'Not all snakes living in the sea are sea snakes,' explains Dr David Gower, Merit Researcher at the Museum and a specialist in snakes.

Biologists use the term 'true sea snake' for any of the 64 recognised species of snakes of the family Elapidae that spend the majority of their lives in the ocean. They even give birth to young in the water. This group otherwise contains land-based snakes such as cobras and mambas.

There are also eight species of sea krait, Laticauda, a semi-aquatic group of reptiles that return to land to lay eggs. Three species of sea krait are also found in freshwater habitats. 

The yellow-bellied sea snake has a very wide distribution, found in almost all tropical waters, other than the Atlantic. It spends it is an aquatic species,  but individuals will sometimes wash up on beaches. © Ken Griffiths/ Shutterstock

'The true sea snakes are more closely related to terrestrial elapids of Australasia than they are to sea kraits,' says David.

Every species of sea snake has fangs at the front of their mouth which permanently stand up. This is a characteristic of members of Elapidae. They can deliver a powerful toxin via their fangs and because they inject it, marine snakes are considered venomous, rather than poisonous.  

The turtle-headed sea snakes, Emydocephalus, are an exception because they have a diet of fish eggs and lack venom. 

A yellow-lipped sea krait on a coral reef. © Rich Carey/ Shutterstock

Master mariners

Sea snakes are generally found in shallow, tropical waters from the eastern Pacific Ocean to the Indian Ocean.

Most species favour coastal waters where they hunt in reefs, seagrass meadows or on the muddy sea floor. The yellow-bellied sea snake, Hydrophis platurus, can also be found far out to sea, preying upon fish near the surface of the water.

'The yellow-bellied sea snake is exceptionally widely distributed, in almost all tropical waters other than the Atlantic, so it is perhaps one of the more likely species to be encountered, including individuals that might be washed up on beaches,' says David.

To help them swim, true sea snakes have evolved tails shaped like paddles and narrow scales along their bellies so that they can maintain a laterally compressed shape to aid swimming. Sea kraits have paddle-like tails too but they have retained the larger belly scales found in their terrestrial ancestors so they can still move efficiently on land.   

Sea snakes have paddle-like tails to help them move through the water. This is the tail of a yellow-bellied sea snake. © NickEvansKZN/ Shutterstock 

Sea snakes have solved a major challenge of life in saltwater thanks to specialised glands in the floor of their mouth that allow them to excrete excess salt.

'Sea snakes show various adaptations to marine life, including having specialised sensory organs on their scales to detect water-borne vibrations and having visual pigments in their retinas that are more tuned away from the wavelengths of light that don't reach deeply into the water,' explains David.

Are sea snakes dangerous?

As part of his research, David joined an expedition off the northwest coast of Australia, working with colleagues and world experts to take tissue samples from around 70 sea snakes, of seven species. Working at night to capture and clip the tail scales of these venomous snakes sounds highly perilous, but the snakes pose little threat to humans if handled with care.

'In general, sea snakes are mellow and not interested in biting humans - unless they are grabbed or picked up aggressively. Most bites from sea snakes are to people trying to remove them from being accidentally tangled in their fishing nets,' explains David.

Sea snakes have relatively small fangs and venom is not always injected with a bite. With bites often occurring in remote places, such as out at sea or in small fishing villages, it's clear why records of sea snake bites are incomplete.

While sea snake bites are certainly far less numerous than terrestrial snake bites, the powerful neurotoxin in the venom causes paralysis, including in the respiratory muscles, which can prove fatal.

A yellow-bellied sea snake from the Museum's spirit collection. Like most other sea snakes, this is a venomous species. 

The title of 'most venomous sea snake' is a subject of debate, thanks in part to an incorrect record that named Belcher's sea snake, Hydrophis belcheri, in a popular book of facts published in the 1990s. Scientists now agree Dubois' sea snake, Aipysurus duboisii, found off the coasts of Papua New Guinea, New Caledonia and Australia, actually has a more potent venom among sea snakes.

Available data are very patchy but the deadliest sea snake in terms of human fatalities may be the beaked sea snake, Hydrophis schistosus. It's described as aggressive and relatively frequently encountered by fishermen in the coastal waters of India.

Want to see a sea snake?

There are sea snake specimens on display at the Museum in London and at Tring in Hertfordshire.

The scientific collections in London hold many sea snake specimens. Book a spirit collection tour to see behind the scenes. 

Sea snake eyes

'One of the aspects of snakes that I am fascinated by is their sensory systems, especially vision,' says David.

'There is an ongoing debate about how snakes evolved from lizards - two of the leading hypotheses are that they became snake-like by acquiring features that were adaptions to either burrowing in soils or to life in the sea, so I have been addressing aspects of this debate by carrying out research on the visual systems of these two groups of snakes.'

Snakes lost some parts of their ancestors' colour vision abilities tens of millions of years ago as they adapted to low-light habitats, but recent research suggests sea snakes have 're-evolved' some of their ability for colour sensitivity. Sea snakes experience highly variable light conditions as they dive for food. Underwater, blue light dominates, and yellow and red light is greatly reduced. They then return to the light of the surface in order to breathe.

Due to this diving behaviour, sea snakes are experts at holding their breath. In 2019 scientists reported the first evidence of snakes swimming to depths of more than 200 metres, into the cool waters of the 'twilight zone', possibly to hunt. Yet sea snakes don't have gills to obtain oxygen from the water like fish.

As well as having lungs that they fill with air during visits to the surface, sea snakes are also able to absorb oxygen into their blood through their skin. Researchers have discovered that the annulated sea snake, Hydrophis cyanocinctus, has a dense network of veins on its forehead and snout that probably helps to get more oxygen to its brain during longer periods underwater.

A preserved annulated sea snake coiled within its collection jar at the Museum

What eats sea snakes?

Fossil evidence of the ancient giant marine snake Palaeophis colossaeus, which measured up to nine metres long, has been discovered in Morocco, firing the imagination with images of enormous sea serpents. But these extinct marine snakes are not very closely related to modern-day sea snakes and sea kraits.

Modern day species also fall short of this monstrous size. The yellow sea snake, Hydrophis spiralis, is recognised as perhaps the longest living sea snake in the world, recorded at nearly 3 metres long.

Most sea snakes feed on fish. Their predators include sharks, large eels, sea eagles and large bony fish such as groupers. There are even records of dolphins hunting the reptiles and of a sea snake being regurgitated by a leopard seal. 

Are sea snakes endangered?

Sea snakes and sea kraits are under threat from humans.

Historically, black-banded sea kraits, Laticauda semifasciata, were hunted for their meat, skin and organs in the Philippines and Japanese islands. Their numbers have not yet recovered following massive harvests in the 1970s and 1980s.

There is currently no CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) protection for any sea snake species.

The olive sea snake is one of the marine snakes that is named for the colour of its scales. This species is found off the coast of Australia and in other Indo-Pacific areas. © Tchami (CC BY-SA 2.0) via Flickr

One of their greatest threats is as bycatch, when they accidentally become entangled in fishing equipment. Climate change also threatens these animals because they are finely adapted to their environment and will suffer the effects of rising sea temperatures and degradation of coral habitats.

A 2009 assessment indicated that 10% of sea snake species were at elevated risk of extinction, with the leaf-scaled sea snake, Aipysurus foliosquama, and short-nosed sea snake, Aipysurus apraefrontalis, considered critically endangered. Examples of both species were discovered off the western coast of Australia in 2015 however, suggesting more attention is needed for these unique marine reptiles.

David says a key way to protect these fascinating snakes is 'by better studying their biology so that we fully understand the inventory of species, their natural histories, distributions, ecological tolerances and conservation threats.'

Need to know more about snakes?

For a comprehensive introduction to the world of snakes, look out for our new book Snakes: Their diversity, ecology and behaviour.

Available from September 2023.

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