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Eunectes murinus
General Details, Taxonomy and Biology, Venom, Clinical Effects, Treatment, First Aid , Antivenoms
Family: Boidae
Subfamily: Boinae
Genus: Eunectes
Species: murinus
Common Names
Anaconda , Green Anaconda , Water Boa Anaconda
Local Names
Culebra de Agua , Anaconda
South America
Bolivia, Brazil, Colombia, French Guiana, Guyana, Peru, Trinidad and Tobago, Venezuela
Taxonomy and Biology
Adult Length: 3.00 m
General Shape
One of the largest of all snakes. Large in length, exceptionally heavy bodied snake with a moderately short, stout tail that terminates with a bluntly rounded tip. Can grow to a maximum of about 10.0 metres with 5.0 to 7.0 metre specimens recorded that have a circumference exceeding one metre and weighing well in excess of 100 kgs. Head is moderately short, broad and distinct from neck. Eyes are medium in size, protruding with vertically elliptical pupils. Dorsal scales are smooth ( but often somewhat rugose vertebrally ), small and hexagonal. Dorsal scale count about 46 - 64 - 36. Cloacal spurs are present.
Seldom found far from water. Found in rivers, streams, lakes, swamps and flooded forest in mainly tropical wet and tropical moist forest but has also been found in seasonally dry forest during the wet seasons.
Semi-aquatic and mainly nocturnal snake.
Feeds mainly on fish, amphibians and reptiles ( including turtles ), birds and mammals ( including pacas, tapir and deer ).
Species Map
Small (Approx 20k) version
General: Venom Neurotoxins
Not present
General: Venom Myotoxins
Not present
General: Venom Procoagulants
Not present
General: Venom Anticoagulants
Not present
General: Venom Haemorrhagins
Not present
General: Venom Nephrotoxins
Not present
General: Venom Cardiotoxins
Not present
General: Venom Necrotoxins
Not present
General: Venom Other
Not present or not significant
Clinical Effects
General: Dangerousness
Bite most unlikely to cause fatality, but death from constriction possible, but rare.
General: Rate of Envenoming: Zero
General: Untreated Lethality Rate: Very low
General: Local Effects
Can cause numerous tooth punctures, with local pain & swelling, potential for secondary infection.
General: Local Necrosis
Does not occur, based on current clinical evidence
General: General Systemic Effects
Does not occur, based on current clinical evidence
General: Neurotoxic Paralysis
Does not occur
General: Myotoxicity
Does not occur
General: Coagulopathy & Haemorrhages
Does not occur
General: Renal Damage
Does not occur
General: Cardiotoxicity
Does not occur
General: Other
Does not occur
First Aid
Description: First aid for bites by pythons, boas and other strictly non-venomous snakes (excluding non-front-fanged colubroid snakes).
If the snake is large and is applying constriction to a vital area, particularly the head, neck, or chest, such that the patient is already, or is in imminent danger of having compromise of vital functions, such as breathing, then the priority is to disengage the snake coils causing such constriction. Beware, for a large snake, constriction of more than one person is possible; if possible get several people to assist in controlling the snake. There are no absolute methods for disengaging a constricting snake, but as a starting point, it may be useful to start by unwrapping from the tail end first, progressively unwinding the snake from the patient. Be sure to have someone control the head of the snake, grasping it firmly on the neck, immediately behind the head, but again beware, as the snake may try to throw constricting coils around the hand, arm, or even body of the person grasping the head and may attempt to lever the head out of the person's grasp, allowing the snake to bite.

If the snake is still biting the patient, grip the snake behind the head and endeavour to withdraw the head from the patient, but do not pull the snake head directly backwards as the teeth are recurved, pointing backwards toward the rear of the mouth. It is possible to break teeth off during this process; these lost teeth may act as a focus for secondary infection if not removed promptly. Often, just gripping the snake behind the head, while removing any coils around the patient, may induce the snake to open its mouth and disengage from biting. This is the preferred outcome. Trying to manually open the snakes mouth to disengage it from biting is very difficult, not least because of the loose connection between the right and left sides of the lower jaw, such that each moves independently.

Once the snake has been removed from the patient and secured where no other person is likely to be harmed, the bite wound should be thoroughly washed with clean, preferably sterile water. Disinfectant may be used. Any jewelry, such as rings or bangles, should be removed from the bitten limb, in case major swelling develops.

If there has been major constriction by a large snake there is the possibility of injuries to limbs or internal organs distant from the bite site. In this setting, early medical attention is required, to assess for such injuries.

For all but minor bites by small snakes, there is a risk of potentially severe local infection. It is therefore advisable, if possible, to seek early medical attention, for update of tetanus immunisation (if required) and consideration of antibiotic treatment.
Treatment Summary
Bites by boas & pythons do not cause envenoming, but can cause local pain, swelling, secondary infection, or rarely, more extensive injury from constriction. The wound should be washed thoroughly. If infection develops, commence targeted antibiotic therapy orally, or in more severe cases, IV. No antivenom is available, nor is it needed, because these snakes are non-venomous.
Key Diagnostic Features
Local teeth marks, pain, swelling
General Approach to Management
Most cases will be minor & not require admission.
Antivenom Therapy
No antivenom available
No Antivenoms
No images
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