Reptilia · Squamata
Amblyrhynchus cristatusBell, 1825
Marine Iguana
Photograph by Shawn O'Donnell, CC BY, via iNaturalist
A day-active, plant-eating lizard from the Neotropic region, reaching 560 mm snout to vent.
Reptilia › Squamata › Iguanidae › Amblyrhynchus
- Grows to
- 560mm
- greatest recorded
- Eats
- Herbivorous
- Active
- Diurnal
- Lives up to
- 28years
Longer than 84% of all iguanas 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 129 to 750 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
46 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
- Vulnerable
- Status assessed · the year the Red List last looked
- 2019
- Population trend
- Decreasing
- Red List criteria
- A2abce+4abce
The animal itself
- Limbs
- Four legs
- Venomous
- No
- Fangs
- None
- Longest recorded life
- 28years
- Preferred body temperature · chosen in a laboratory gradientmeasured
- 32.9°C
- Body temperature when active · measured in the wild
- 31.7°C89 °F
- Body temp in the wild · mean, when active
- 25.5–37.9°C78–100 °F
Carey and Judge 2000, De Magalhaes & Costa 2009: 6.4 (Captivity); Wikelski and Thom 2000: 28; Petzold 2008: 6.5, Artega et al. 2019: estimated 30
mean body temperature of active individuals in nature
body temperature of active animals in nature
Size
- Length snout to vent · greatest recorded
- 560mm22 in
- Length snout to vent · adult female mean
- 320mm12.5 in
- Largest female · snout to vent
- 320mm12.5 in
- Hatchling length · snout to vent
- 110.5mm4.25 in
- Largest juvenile · snout to vent
- 110.5mm4.25 in
- Body mass · greatestcomputed
- 7406.5g16 lb
- Body mass · a typical adult
- 2227.4g4.9 lb
- Body mass · adult female, meanmeasured
- 3595g7.9 lb
- Body mass at hatchingmeasured
- 69g2.4 oz
max 560 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
AnAge rates this record "acceptable"
How it lives
- Diet
- Herbivorous
- Active
- Diurnal
- Where it lives
- Marine
- Habitat
- Marine Neritic, Shrubland
- Biome
- Deserts & Xeric Shrublands
- Region
- Neotropic
- Mainland or island
- Found only on islands
- Highest it lives · above sea level
- 10m
- Range size
- 7990km²
- Density
- 889per hectare
- Home range · largest recorded
- 38.8m2
(see Zug 2013), but "will also ingest" invertebrates, carrion, "and even sea lion feces and afterbirth" (Artega et al. 2019)
e.g., Artega et al. 2019
marine, mostly terrestrial spends up to 5% of its time at sea (Artega et al. 2019)
Breeding
- Reproduction
- Oviparous
- Average clutch
- 2.25eggs
- Eggs or young per clutch
- 1–6eggs
- Mean clutch
- 2–2.5eggs
- Clutches in a year
- 0.51per year
- Clutches a year
- 0.5–0.51per year
- First breeds at
- 41months
depends on island, from 1 to a maximum of 6 and increases with svl (Wikelski & Romero 2003), 1-6 (Zug 2013, Artega et al. 2019)
Naming and history
- Suborder
- Sauria
- Infraorder
- Pleurodonta
- Subspecies
- Amblyrhynchus cristatus cristatus BELL 1825 Amblyrhynchus cristatus godzilla MIRALLES, MACLEOD, RODRÍGUEZ, IBÁÑEZ, JIMÉNEZ-UZCATEGUI, QUEZADA, VENCES & STEINFARTZ 2017 Amblyrhynchus cristatus hassi EIBL-EIBESFELDT 1962 Amblyrhynchus cristatus hayampi MIRALLES, MACLEOD, RODRÍGUEZ, IBÁÑEZ, JIMÉNEZ-UZCATEGUI, QUEZADA, VENCES & STEINFARTZ 2017 Amblyrhynchus cristatus jeffreysi MIRALLES, MACLEOD, RODRÍGUEZ, IBÁÑEZ, JIMÉNEZ-UZCATEGUI, QUEZADA, VENCES & STEINFARTZ 2017 Amblyrhynchus cristatus mertensi EIBL-EIBESFELDT 1962 Amblyrhynchus cristatus nanus GARMAN 1892 Amblyrhynchus cristatus sielmanni EIBL-EIBESFELDT 1962 Amblyrhynchus cristatus trillmichi MIRALLES, MACLEOD, RODRÍGUEZ, IBÁÑEZ, JIMÉNEZ-UZCATEGUI, QUEZADA, VENCES & STEINFARTZ 2017 Amblyrhynchus cristatus venustissimus EIBL-EIBESFELDT 1956 Amblyrhynchus cristatus wikelskii MIRALLES, MACLEOD, RODRÍGUEZ, IBÁÑEZ, JIMÉNEZ-UZCATEGUI, QUEZADA, VENCES & STEINFARTZ 2017
- Described by
- Bell
- Moved to another genus · since it was first described
- No
- Described in
- 1825
- Type locality
- Ecuador (Galapagos)
Keeping one
Marine Iguana is assessed as Vulnerable on the IUCN Red List. Species at risk in the wild are often covered by CITES and by national law, which decide what may be bought, sold, moved across a border or kept at all — and captive-bred and wild-caught animals are usually treated differently. Check the rules where you are before acquiring one. Nothing below is a judgement about keeping this species; it is what a published welfare standard says about space, and what the animal itself was measured doing.
7 ft 4 in × 7 ft 4 in × 4 ft 7 in(224 × 224 × 140 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 22 in (560 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 91 °F (32.9 °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
Prey size does not apply. A herbivore's diet is judged on fibre, on the ratio of calcium to phosphorus, and on avoiding plants high in oxalates.
The animal does not take prey items. This is established practice, not a measurement.
540kJ per day
Worked out for an animal of 7,407 g, the heaviest recorded for Marine Iguana — 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
- — Eats arthropods
- — Eats vertebrates
- — Eats plant matter
- — How it hunts
- — How the young develop
- — Gestation or incubation
- — 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
- — Active season · shortest recorded
- — Active season · longest recorded
- — Active in
- — Lowest it lives · above sea level
Others in Iguanidae
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). Amblyrhynchus cristatus. Retrieved 2026-09-08, from https://www.allanglescreatures.com/species/amblyrhynchus-cristatus
@misc{amblyrhynchus_cristatus_2026,
title = {Amblyrhynchus cristatus},
author = {{The Reptile & Amphibian Encyclopedia}},
year = {2026},
url = {https://www.allanglescreatures.com/species/amblyrhynchus-cristatus}
}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.
- AnAge, Human Ageing Genomic Resources (de Magalhães et al.), used under CC BY 3.0.