Reptilia · Squamata
Achalinus formosanusBoulenger, 1908
Formosa Odd-scaled Snake
Photograph by Sin Syue Li, CC BY, via Wikimedia Commons
A nocturnal, meat-eating lizard from the Oriental region, reaching 853 mm nose to tail.
Reptilia › Squamata › Xenodermidae › Achalinus
- Grows to
- 853mm
- greatest recorded
- Eats
- Carnivorous
- Active
- Nocturnal
- Lives
- Fossorial, terrestrial
Longer than 94% of all species in Xenodermidae anyone has measured.
The bar is the rank itself: its length is the share of the family this animal exceeds. The chart below is the family’s real spread, on a logarithmic scale because body length here runs from 177.9 to 870 mm. The solid rule is this animal. Every bar is a count of real species, and nothing on this figure is estimated.
What is known
32 sourced facts, each taken from a named scientific dataset. How to read these.
Cited from a dataset unless a row is marked otherwise.
Standing in the world
- Still living
- Extant
- Conservation status
- Least Concern
- Status assessed · the year the Red List last looked
- 2016
- Population trend
- Decreasing
The animal itself
- Limbs
- None
- Colour on the back
- Brown
- Pattern on the back
- Striped
- Pupil
- Round
- Venomous
- No
- Fangs
- At the back of the mouth
Size
- Length snout to vent · greatest recorded
- 720mm2 ft 4 in
- Length nose to tail · greatest recorded
- 853mm2 ft 10 in
- Body mass · greatestcomputed
- 115.7g4.1 oz
Chen et al. 2019 (listed as SVL, I suspect it may be total length), (?), Li et al. 2020 (TL), Fukuyama and Fukuyama 2021 (female, 287 mm SVL, 412 mm total length), Ha et al. 2022 (450 mm total length, 252 mm SVL for A. formosanus chigirai and 853 TL, 717 mm SVL for A. f.formosanus)
snakes only in this source
computed from length by a family-level allometric equation, not weighed
How it lives
- Diet
- Carnivorous
- How it hunts
- Active foraging
- Active
- Nocturnal
- Where it lives
- Fossorial, terrestrial
- Habitat
- Forest
- Biome
- Tropical & Subtropical Moist Broadleaf Forests
- Region
- Oriental
- Mainland or island
- Found only on islands
- Lowest it lives · above sea level
- 1000m
- Highest it lives · above sea level
- 1990m
- Range size
- 36,704km²
earthworms (Fukuyama and Fukuyama 2021)
Active (O'Shea 2018)
Wang et al. 2023
Fossorial&Terrestrial (O'Shea 2018)
<2000 (O'Shea 2018)
Breeding
- Reproduction
- Oviparous
O'Shea 2018
Naming and history
- Suborder
- Serpentes
- Infraorder
- Alethinophidia
- Subspecies
- Achalinus formosanus chigirai OTA & TOYAMA 1989 Achalinus formosanus formosanus BOULENGER 1908
- Described by
- Boulenger
- Moved to another genus · since it was first described
- No
- Described in
- 1908
- Type locality
- Taiwan
Keeping one
9 ft 5 in × 9 ft 5 in × 5 ft 11 in(288 × 288 × 180 cm)
Minimum length × width × height, for one animal. Bigger is always better. Substrate at least 14 in (36 cm) deep.
The standard sizes ground-dwelling species at 4 × 4 × 2.5 times snout-vent length.
Burrows, so substrate deep enough to dig in matters as much as floor area.
Mindestanforderungen an die Haltung von Reptilien (Sachverständigengutachten), German Federal Ministry for Nutrition, Agriculture and Forestry, Animal Welfare Division, 10 January 1997. The standard states these floor areas are recommendations rather than binding limits.
From this animal’s own snout-vent length of 2 ft 4 in (720 mm), at 4 × 4 × 2.5 times it, following the German federal welfare standard — how this is worked out.
No preferred body temperature has been recorded for Formosa Odd-scaled Snake. Rather than repeat a number from a care sheet, this page leaves it out.
Feeding
A prey item should be no wider than the space between the animal's eyes.
Widely used across reptile husbandry references. The stated reason is that the gap approximates the width of the throat, so wider prey is associated with impaction. This is established practice, not a measurement.
13kJ per day
Worked out for an animal of 116 g, the heaviest recorded for Formosa Odd-scaled Snake — so it is the top of the range, not a figure for a particular animal. Weigh yours and the number will be lower.
An upper estimate, not a feeding target, and not veterinary advice. The equation covers only what an animal burns staying alive, so a growing, gravid or recovering animal needs more — and it was measured on wild animals, which move far more than one in an enclosure. Body condition and a vet who knows the species are what a feeding decision should rest on. Where this comes from.
What nobody knows
These are not gaps in our research. No scientific dataset records them for this species — and saying so is information you cannot get from a reference that simply leaves a field out.
- — Length snout to vent · adult female mean
- — Length snout to vent · adult male mean
- — Length snout to vent · adult mean
- — Female length · mean, nose to tail
- — Length nose to tail · adult male mean
- — Length nose to tail · adult mean
- — Largest female · snout to vent
- — Largest male · snout to vent
- — Largest female · shell length
- — Largest male · shell length
- — Hatchling length · snout to vent
- — Hatchling length · nose to tail
- — Largest juvenile · snout to vent
- — Largest juvenile · shell length
- — Egg length
- — Egg width
- — Body mass · a typical adult
- — Body mass · adult female, mean
- — Body mass at hatching
- — Longest recorded life
- — Preferred body temperature · chosen in a laboratory gradient
- — Body temperature when active · measured in the wild
- — Eats arthropods
- — Eats vertebrates
- — Eats plant matter
- — How the young develop
- — Gestation or incubation
- — Average clutch
- — Smallest clutch recorded
- — Largest clutch recorded
- — Mean clutch · smallest reported
- — Mean clutch · largest reported
- — Clutches in a year
- — Clutches a year · fewest
- — Clutches a year · most
- — First breeds from · youngest recorded
- — First breeds by · oldest recorded
- — Hatchling length · smallest recorded
- — Hatchling length · largest recorded
- — Age at first breeding · female
- — Mature from · youngest recorded
- — Mature by · oldest recorded
- — Size at maturity · smallest recorded
- — Size at maturity · largest recorded
- — Body temp in the wild · lowest mean recorded
- — Body temp in the wild · highest mean recorded
- — Sex decided by
- — Red List criteria
- — Active season · shortest recorded
- — Active season · longest recorded
- — Density · lowest recorded
- — Density · highest recorded
- — Home range · largest recorded
- — Active in
Others in Xenodermidae
Take this data
Everything on this page is available as data under CC BY 4.0 — use it freely, credit it, no permission needed.
This species as JSON · the whole dataset
Cite this page
The Reptile & Amphibian Encyclopedia (2026). Achalinus formosanus. Retrieved 2026-09-08, from https://www.allanglescreatures.com/species/achalinus-formosanus
@misc{achalinus_formosanus_2026,
title = {Achalinus formosanus},
author = {{The Reptile & Amphibian Encyclopedia}},
year = {2026},
url = {https://www.allanglescreatures.com/species/achalinus-formosanus}
}Sources
- Meiri, S. (2024). SquamBase — a database of squamate (Reptilia: Squamata) traits. Global Ecology and Biogeography. Public domain (CC0).
- Catalogue of Life (dataset 3LR), used under CC BY.
- Oskyrko, O. et al. (2024). ReptTraits: a comprehensive dataset of ecological traits in reptiles. Scientific Data. Used under CC BY 4.0.