Reptilia · Squamata
Varanus semiremexPeters, 1869
Rusty Monitor
Photograph by dhfischer, CC BY, via iNaturalist
A day-active, meat-eating monitor lizard from the Australo-Pacific region, reaching 282 mm snout to vent.
Reptilia › Squamata › Varanidae › Varanus
- Grows to
- 282mm
- greatest recorded
- Eats
- Carnivorous
- Active
- Diurnal
- Lives
- Semi-aquatic
Longer than only 24% of all monitor lizards 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 116.4 to 1,570 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
34 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
- 2017
The animal itself
- Limbs
- Four legs
- Fangs
- None
Size
- Length snout to vent · greatest recorded
- 282mm11 in
- Length snout to vent · adult female mean
- 228mm9 in
- Largest female · snout to vent
- 228mm9 in
- Hatchling length · snout to vent
- 69mm2.75 in
- Largest juvenile · snout to vent
- 73.9mm3 in
- Body mass · greatestcomputed
- 422.2g14.9 oz
- Body mass at hatchingmeasured
- 4.5g0.16 oz
max 282 mm SVL (Feldman et al. 2016)
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
- Diurnal
- Where it lives
- Semi-aquatic
- Habitat
- Forest, Wetlands
- Biome
- Tropical & Subtropical Grasslands, Savannas & Shrublands
- Region
- Australo-Pacific
- Mainland or island
- Mainland
- Highest it lives · above sea level
- 200m
- Range size
- 202,417km²
Vertebrates and Invertebrates: Fish crabs insects and lizards, frogs and mammals (Arbuckle 2009), crabs, fish, insects, frogs & mammals (Bennett 1995), arthropods incl. insects, spiders and crabs as well as vertebrates (Jackson 2005)
(Jackson 2005 says activity follows the tide, not mentioning the diel cycle), Diurnal (Auliya and Koch 2020)
Semi Aquatic and Arboreal (e.g., Jackson 2005, Auliya and Koch 2020)
IUCN (0 to 200)
Breeding
- Reproduction
- Oviparous
- Average clutch
- 5.6eggs
- Eggs or young per clutch
- 2–21eggs
- Mean clutch
- 2–12.5eggs
- Clutches a year
- 1–3per year
- First breeds at
- 15months
2-14 (Bennett 1995), 8-21 (Jackson 2005; 125 eggs in 10 clutches), 2-21 (Auliya and Koch 2020)
Naming and history
- Suborder
- Sauria
- Infraorder
- Anguimoprha
- Subspecies
- No
- Described by
- Peters
- Moved to another genus · since it was first described
- No
- Described in
- 1869
- Type locality
- Australia
Keeping one
3 ft 8 in × 3 ft 8 in × 2 ft 4 in(113 × 113 × 71 cm)
Minimum length × width × height, for one animal. Bigger is always better.
The standard sizes ground-dwelling species at 4 × 4 × 2.5 times snout-vent length.
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 11 in (282 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 Rusty Monitor. 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.
42kJ per day
Worked out for an animal of 422 g, the heaviest recorded for Rusty Monitor — 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
- — Body mass · adult female, mean
- — 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 it hunts
- — How the young develop
- — Gestation or incubation
- — Clutches in a year
- — 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
- — Venomous
- — Body temp in the wild · lowest mean recorded
- — Body temp in the wild · highest mean 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
- — Lowest it lives · above sea level
Others in Varanidae
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). Varanus semiremex. Retrieved 2026-09-08, from https://www.allanglescreatures.com/species/varanus-semiremex
@misc{varanus_semiremex_2026,
title = {Varanus semiremex},
author = {{The Reptile & Amphibian Encyclopedia}},
year = {2026},
url = {https://www.allanglescreatures.com/species/varanus-semiremex}
}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.