Reptilia · Squamata
Amphisbaena mertensiiStrauch, 1881
Mertens' Worm Lizard
Photograph by Rony Ristow, CC BY, via iNaturalist
A burrowing, nocturnal, meat-eating lizard from the Neotropic region, reaching 458 mm snout to vent.
Reptilia › Squamata › Amphisbaenidae › Amphisbaena
- Grows to
- 458mm
- greatest recorded
- Eats
- Carnivorous
- Active
- Nocturnal
- Lives
- Fossorial
Longer than 90% of all species in Amphisbaenidae 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 107 to 810 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
37 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
- 2014
The animal itself
- Limbs
- None
- Venomous
- No
- Fangs
- None
- Preferred body temperature · chosen in a laboratory gradientmeasured
- 21.4°C
- Body temperature when active · measured in the wild
- 22.35°C72 °F
- Body temp in the wild · mean, when active
- 21.1–23.6°C70–74 °F
mean body temperature of active individuals in nature
body temperature of active animals in nature
Size
- Length snout to vent · greatest recorded
- 458mm18 in
- Length snout to vent · adult female mean
- 366.7mm14.5 in
- Largest female · snout to vent
- 366.7mm14.5 in
- Hatchling length · snout to vent
- 107mm4.25 in
- Largest juvenile · snout to vent
- 107mm4.25 in
- Body mass · greatestcomputed
- 113.1g4 oz
- Body mass · adult female, meanmeasured
- 27.5g0.97 oz
- Body mass at hatchingmeasured
- 1.7g0.06 oz
Assis et al. 2022 (max 458 mm)
snout-vent length; the source column mixes this with straight carapace length
computed from length by a family-level allometric equation, not weighed
How it lives
- Diet
- Carnivorous
- Active
- Nocturnal
- Where it lives
- Fossorial
- Habitat
- Forest, Savanna
- Biome
- Tropical & Subtropical Grasslands, Savannas & Shrublands
- Region
- Neotropic
- Mainland or island
- Mainland
- Elevation · above sea level
- 650–660m
- Range size
- 816,727km²
invertebrates (in captivity, Andrade et al. 2006) / termites (Bernardo-Silva et al. 2006), mainly ants (Lisboa et al. 2016), see also Correa and Meneses 2020
"may be seen foraging on surface at afternoon and night"
e.g., Rodda 2020, Assis et al. 2022
Breeding
- Reproduction
- Oviparous
- Average clutch
- 7eggs
- Eggs or young per clutch
- 6–8eggs
- Mean clutch
- 7eggs
6 (Andrade et al. 2006), 6-8 (Aguirre et al. 2017)
Naming and history
- Suborder
- Amphisbaenia
- Infraorder
- Amphisbaenia (Laterata)
- Subspecies
- No
- Described by
- Strauch
- Moved to another genus · since it was first described
- No
- Described in
- 1881
- Type locality
- Brazil
Keeping one
6 ft × 6 ft × 3 ft 9 in(183 × 183 × 115 cm)
Minimum length × width × height, for one animal. Bigger is always better. Substrate at least 9 in (23 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 18 in (458 mm), at 4 × 4 × 2.5 times it, following the German federal welfare standard — how this is worked out.
In a laboratory thermal gradient this species settled at 71 °F (21.4 °C).
Preferred body temperature, recorded in a laboratory gradient where the animal could choose freely. A measurement of the animal, not a setting for a thermostat.
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 113 g, the heaviest recorded for Mertens' Worm Lizard — 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 male mean
- — Length snout to vent · adult mean
- — Length nose to tail · greatest recorded
- — Female length · mean, nose to tail
- — Length nose to tail · adult male mean
- — Length nose to tail · adult mean
- — Largest male · snout to vent
- — Largest female · shell length
- — Largest male · shell length
- — Hatchling length · nose to tail
- — Largest juvenile · shell length
- — Egg length
- — Egg width
- — Body mass · a typical adult
- — Longest recorded life
- — Eats arthropods
- — Eats vertebrates
- — Eats plant matter
- — How it hunts
- — How the young develop
- — Gestation or incubation
- — 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
- — Colour on the back
- — Pattern on the back
- — Pupil
- — Sex decided by
- — Population trend
- — 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 Amphisbaenidae
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). Amphisbaena mertensii. Retrieved 2026-09-08, from https://www.allanglescreatures.com/species/amphisbaena-mertensii
@misc{amphisbaena_mertensii_2026,
title = {Amphisbaena mertensii},
author = {{The Reptile & Amphibian Encyclopedia}},
year = {2026},
url = {https://www.allanglescreatures.com/species/amphisbaena-mertensii}
}Sources
- Meiri, S. (2024). SquamBase — a database of squamate (Reptilia: Squamata) traits. Global Ecology and Biogeography. Public domain (CC0).
- Oskyrko, O. et al. (2024). ReptTraits: a comprehensive dataset of ecological traits in reptiles. Scientific Data. Used under CC BY 4.0.
- Catalogue of Life (dataset 3LR), used under CC BY.