The largest living snakes in the world, measured either by length or by weight, are various members of the Boidae and Pythonidae families. They include anacondas, pythons and boa constrictors, which are all non-venomousconstrictors. The longest venomous snake, with a length up to, is the king cobra,[1] while contesters for the heaviest title include the Gaboon viper and the Eastern diamondback rattlesnake. All of these three species reach a maximum mass in the range of .
There are fourteen or fifteen living snake species that clearly have a maximum mass of at least, as shown in the table below. Whether the number is fourteen or fifteen depends on whether a DNA analysis reported in 2024 results in the recognition of the northern green anaconda ("Eunectes akayima", listed in row 1b below) as a species distinct from the ordinary (southern) green anaconda (Eunectes murinus). These include all species that reach a length of at least . There are also two other species that reach nearly this length the Oenpelli python (binomial name Nyctophilopython oenpelliensis, Simalia oenpelliensis or Morelia oenpelliensis),[2] and the olive python (Liasis olivaceus). The information available about these two species is rather limited. The Oenpelli python, in particular, has been called the rarest python in the world.[3] [4] [5]
It is important to be aware that there is considerable variation in the maximum reported size of these species, and most measurements are not truly verifiable, so the sizes listed should not be considered definitive. In general, the reported lengths are likely to be somewhat overestimated. In spite of what has been, for many years, a standing offer of a large financial reward (initially $1,000 offered by U.S. President Theodore Roosevelt in the early 1900s,[6] later raised to $5,000, then $15,000 in 1978 and $50,000 in 1980) for a live, healthy snake over long by the New York Zoological Society (later renamed as the Wildlife Conservation Society), no attempt to claim the reward has ever been made.[7]
Although it is generally accepted that the reticulated python is the world's longest snake, most length estimates longer than have been called into question. It has been suggested that confident length records for the largest snakes must be established from a dead body soon after death, or alternatively from a heavily sedated snake, using a steel tape and in the presence of witnesses, and must be published (and preferably recorded on video). At least one reticulated python was measured under full anesthesia at, and somewhat less reliable scientific reports up to have appeared.[8]
Although weight is easier to measure reliably than length (e.g., by simply measuring the weight of a container with and without the snake inside it and subtracting one measurement from the other), a significant factor in the weight of a snake is whether it has been kept in captivity and provided an unusual abundance of food in conditions that also cause reduced levels of activity. Moreover, the weight of wild specimens is often reduced as a symptom of parasite infestations that are eliminated by veterinary care in captivity. Thus, the largest weights measured for captive specimens often greatly exceed the largest weights observed in the wild for the same species. This phenomenon may particularly affect the weight measurements for anaconda species that are especially difficult to keep in captivity due to their semi-aquatic nature, resulting in other species having larger weights measured in captivity. In particular, the green anaconda (Eunectes murinus) is an especially massive snake if only observations in the wild are considered.
| Rank | Common name | Scientific name | Family | Mass | Image | Length | Range map | |
|---|---|---|---|---|---|---|---|---|
| 1 | Green anaconda (a.k.a. Southern green anaconda) | Eunectes murinus | Boidae | May exceed,[9] measurement validity questionable , reliable, maximum among 780 specimens caught over a seven-year period 1992–98[10] Average among 45 specimens (1992–98) Generally considered the heaviest in the wild (exceeded by P.bivittatus and M. reticulatus in captivity) Some specimens may be of a distinct "northern green anaconda" species. | May exceed, not firmly verified , somewhat reliable[11] , somewhat reliable , reliable, maximum among 780 specimens caught over a seven-year period 1992–98 Average among 45 specimens (1992–98) Minimum adult length Some specimens may be of a distinct "northern green anaconda" species. | |||
| 1b | Northern green anaconda (asserted distinct in 2024) | "Eunectes akayima" (asserted distinct in 2024) | Boidae | Similar in maximum weight to that listed above for the southern green anaconda | Similar in maximum length to that listed above for the southern green anaconda Reportedly at least, from a newspaper report not firmly verified[12] | Specimens from light green circled locations | ||
| 2 | Burmese python | Python bivittatus (now recognized as distinct from P. molurus) | Pythonidae | , reliable, for "Baby" in 1998 (in captivity)[13] , reliable, for the heaviest specimen found in the wild[14] [15] [16] , reliable, for the biggest male in the wild< | -- Low-quality sourcing? -->[17] [18] [19] | , reliable, for the longest specimen found in the wild July 10, 2023[20] [21] [22] Minimum adult length | ||
| 3 | Reticulated python | Malayopython reticulatus | Pythonidae | Up to, somewhat reliable[23] , somewhat reliable, for "Medusa" in 2011 About, somewhat reliable, for "Twinkie" in 2014[24] , somewhat reliable, for "Fluffy" in 2010 133.7kg (294.8lb), reasonably reliable, for "Colossus" in 1954 (with an empty stomach)[25] , somewhat reliable, for "Samantha" in 2002[26] , somewhat reliable, for "Super Snake" in 2021[27] [28] [29] , reliable, wild specimen in 1999 (after not eating for nearly 3 months) | ,[30] not firmly verified , somewhat reliable, for "Samantha" in 2002 , somewhat reliable, for "Medusa" in 2011[31] , somewhat reliable, for "Fluffy" in 2010[32] , somewhat reliable, for "Twinkie" in 2014[33] , somewhat reliable, for "Super Snake" in 2021 , reliable, wild specimen in 1999 , reasonably reliable, for "Colossus" in 1963 (skeletal length) Specimens longer than are rare Minimum adult length Generally considered the world's longest | |||
| 4 | Central African rock python | Python sebae (now recognized as distinct from P. natalensis) | Pythonidae | Up to,[34] not firmly verified , reliable[35] [36] [37] | Up to,[38] not firmly verified , reliable[39] Minimum adult length | Range shown as green region | ||
| 5 | Southern African rock python | Python natalensis (now recognized as distinct from P. sebae) | Pythonidae | , somewhat reliable, for the largest specimen[40] , reliable[41] Of 75 specimens measured in South Africa, the longest female weighed .[42] | [43] not firmly verified , reliable Of 75 specimens measured in South Africa, the longest female was long. Specimens longer than are rare.[44] Typically [45] | Range shown as orange region | ||
| 6 | Indian python | Python molurus (now recognized as distinct from P. bivittatus) | Pythonidae | , not firmly verified , reliable[46] | ,[47] not firmly verified , reliable | |||
| 7 | Australian scrub python | Simalia kinghorni (now recognized as distinct from S. amethistina) | Pythonidae | ,[48] reliable , reliable[49] [50] | Some reports up to or exceeding, not firmly verified ,[51] not firmly verified In excess of [52] , reliable Typically Minimum adult length Little information about size is available[53] | Range shown as dark green region | ||
| 8 | Amethystine python | Simalia amethistina (recently recognized as distinct from S. kinghorni) | Pythonidae | Able to reach, and probably larger Little information about size is available | Able to reach [54] , reliable[55] Little information about size is available | Range shown as dark orange and bright orange regions | ||
| 9 | Yellow anaconda | Eunectes notaeus | Boidae | They commonly weigh, though large specimens can weigh or even more.[56] | , reasonably reliable[57] Typically maximum among 86 specimens in a field study[58] | South America | ||
| 10 | Red tailed boa | Boa constrictor | Boidae | More than [59] | Possibly up to [60] A much larger report was debunked[61] | [62] | ||
| 11 | Cuban boa | Chilabothrus angulifer | Boidae | Maximum, reliable[63] , reliable[64] | , for the largest specimen Up to [65] | |||
| 12 | Beni anaconda | Eunectes beniensis (now recognized as distinct from E. murinus and E. notaeus) | Boidae | Largest specimen,[66] relatively reliable Typically up to,[67] [68] relatively reliable Little information about size is available (known from only six specimens as of 2009)[69] | ||||
| 13 | Dark-spotted anaconda | Eunectes deschauenseei (sometimes confused with E. notaeus) | Boidae | ,[70] [71] relatively reliable | ||||
| 14 | Papuan python | Apodora papuana | Pythonidae | Average reported as [72] Little information about size is available | One reasonably reliable report of [73] Average reported as Often reaches Most specimens Little information about size is available |
Individual specimens considered among largest measured for their respective species include the following: