Giant anaconda

The green anaconda, Eunectes murinus, is the largest anaconda species. Females are bigger than their male counterparts.

Reports of giant anaconda date back as far as the discovery of South America when sightings of snakes upwards of 11 meters (33.5 ft) began to circulate amongst colonists and the topic has been a subject of debate ever since among cryptozoologists and zoologists. Anacondas normally only grow to size of 6 metres (20 ft), and 250 kilos in weight, but tales of truly gigantic specimens persist. Indeed, although some python species can grow longer in length, the anaconda, particularly the Green Anaconda, is the heaviest and largest in terms of diameter of all snakes, and is often considered the biggest extant snake in the world. It is not uncommon for a fully grown anaconda to attack and kill a jaguar or crocodile. Yet, despite the snake's large size, no specimens above the size of 35 feet (11 m) have been captured, and anacondas of this proportion are considered cryptids.

The first recorded sightings of giant anacondas were from the time of the discovery of South America, when early European explorers entered the dense jungles there and claimed to have seen giant snakes measuring up to 60 feet (18 m) long. Natives also reported seeing anacondas upwards of 50 feet (15 m) to 60 feet (18 m) It is unquestionable that anacondas above 30 ft (9.1 m) in length are rare; the Wildlife Conservation Society has, since the early 20th century, offered a large cash reward (currently worth US$50,000) for live delivery of any snake of 30 feet (9.1 m) or more in length, but the prize has never been claimed despite the numerous sightings of giant anacondas. In a survey of 1,000 wild anacondas in Venezuela, the largest captured was 17 feet (5.2 m) long, far short of the length required.

A specimen measured in 1944 exceeded this size when a petroleum expedition in Colombia claimed to have measured an anaconda which was 37.5 ft (11.4 m) in length, but this has never been proven. Scientist Vincent Roth also claimed to have shot and killed a 10.3 metres (34 ft) specimen, but like most other claims, this has never been proven. Another claim of an extraordinarily large anaconda was made by adventurer Percy Fawcett. During his 1906 expedition, Fawcett wrote that he had shot an anaconda that measured some 62 feet (19 m) from nose to tail. Once published, Fawcett’s account was widely ridiculed. Decades later, Belgian zoologist Bernard Heuvelmans came to Fawcett's defense, arguing that Fawcett's writing was generally honest and reliable. Historian Mike Dash writes of claims of still larger anacondas, alleged to be as long as 100-150 ft (30–45 m) — some of the sightings supported with photos (although those photos lack scale). Dash notes that if a 50–60 ft anaconda strains credulity, then a 150 ft long specimen is generally regarded as an outright impossibility.There could be a few legendary giants out there but these would have to be extremely rare, possibly reaching lengths of over 45 to possibly 50 feet (15 m).

Recently an anaconda measuring over six meters (more than 19 feet) and weighing nearly 200 kilos (440 pounds) was captured in the backyard of an abandoned house in Parana, Brazil.