B
Species Profile

Blue Iguana

Cyclura lewisi

Grand Cayman's comeback lizard
DnDavis/Shutterstock.com

Blue Iguana Distribution

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Endemic Species
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Grand Cayman Blue Iguana. Cyclura lewisi is an endangered species and is native to the Cayman islands

At a Glance

Wild Species
Also Known As Grand Cayman iguana, Cayman iguana, Cayman Islands iguana, Grand Cayman rock iguana
Diet Omnivore
Activity Diurnal+
Lifespan 30 years
Weight 14 lbs
Status Endangered
Did You Know?

Size: adults reach about 1.5 m total length, with heavy-bodied Cyclura proportions (IUCN Red List species account).

Scientific Classification

A large, primarily terrestrial Caribbean rock iguana endemic to Grand Cayman, known for its distinctive bluish-gray coloration (especially in adult males) and robust build.

Kingdom
Animalia
Phylum
Chordata
Class
Reptilia
Order
Squamata
Family
Iguanidae
Genus
Cyclura
Species
Cyclura lewisi

Distinguishing Features

  • Stout-bodied rock iguana with a prominent dorsal crest/spines
  • Bluish-gray to turquoise coloration in adults (males often most vivid), with darker banding
  • Large head with powerful jaws; heavy limbs adapted for terrestrial life
  • Herbivorous/mostly plant-based diet typical of Cyclura rock iguanas

Physical Measurements

Males and females differ in size

Length
♂ 4 ft 9 in (4 ft 3 in – 4 ft 11 in)
♀ 4 ft 3 in (3 ft 11 in – 4 ft 5 in)
Weight
♂ 24 lbs (18 lbs – 31 lbs)
♀ 13 lbs (10 lbs – 17 lbs)
Tail Length
♂ 3 ft 1 in (2 ft 9 in – 3 ft 3 in)
♀ 2 ft 6 in (2 ft 4 in – 2 ft 7 in)
Top Speed
9 mph
About 15 km/h

Appearance

Primary Colors
Secondary Colors
Skin Type Dry, hard, overlapping scales with larger rough bumps (tubercles); a strong midline crest of spine-like scales from neck down the back; thick ringed tail scales for ground life in dry rocky habitats (Cyclura lewisi).
Distinctive Features
  • Robust Cyclura (rock-iguana) build: heavy-bodied, broad-chested, primarily terrestrial lizard of xeric scrub/rocky limestone habitats; endemic (island-restricted) to Grand Cayman (IUCN Red List: Cyclura lewisi).
  • Large adults can reach about 1.5 m in total length and weigh up to about 14 kg; these size numbers are commonly reported for Cyclura lewisi in IUCN and conservation papers.
  • Prominent dorsal crest (spines) and a large, muscular, laterally compressed tail with distinct ringed scalation; tail used for balance/defense and as a visual signal.
  • Large head with pronounced jowls in mature males; visible subtympanic scale typical of iguanids; well-developed dewlap (gular fold) used in display.
  • Strong limbs with long digits and sharp claws suited to digging burrows and moving over rock; commonly basks in open sun and retreats to crevices/burrows (terrestrial, wary behavior; not venomous).
  • Color shifts with sex/season: males often become more vividly blue during breeding season; females and juveniles tend to be grayer/browner with more obvious dark markings (IUCN Red List: Cyclura lewisi).
  • Conservation-context trait: many individuals in the modern wild population originate from head-starting/reintroduction efforts; threats historically included habitat loss and invasive predators (context from published recovery program summaries; IUCN Red List: Cyclura lewisi).

Sexual Dimorphism

Sexual dimorphism is evident in both size and coloration: adult males are generally larger with broader heads/jowls and often more intense blue coloration (especially seasonally), while females are typically smaller and grayer with less exaggerated head and crest features (IUCN Red List: Cyclura lewisi).

♂
  • Often more vivid blue overall (commonly strongest in breeding season), sometimes appearing slate-blue to bright blue compared with females (IUCN Red List: Cyclura lewisi).
  • Typically larger-bodied with a proportionally broader head and more pronounced jowls.
  • More prominent femoral pores and hemipenal bulges at tail base (external sexual characters typical of iguanids/Cyclura).
  • Dorsal crest and display structures (dewlap) often appear more developed/visually striking in mature males.
♀
  • Generally smaller and more gray/gray-brown overall, with less intense blue coloration (IUCN Red List: Cyclura lewisi).
  • Head/jowls typically less massive; femoral pores less enlarged/less conspicuous than in males.
  • Dorsal crest and dewlap present but usually less visually exaggerated than in mature males.

Did You Know?

Size: adults reach about 1.5 m total length, with heavy-bodied Cyclura proportions (IUCN Red List species account).

Sexual dimorphism: adult males typically become much bluer (bluish-gray to sky-blue), while females/juveniles stay more olive/gray-brown-color linked to maturity and signaling in territorial displays.

Longevity: like other West Indian rock iguanas (Cyclura), individuals can live for decades; captive longevities of 40+ years are reported for the genus, and C. lewisi is considered similarly long-lived (zoo/field program records; Cyclura husbandry literature).

Reproduction: females lay a single annual clutch in a nest burrow; clutch sizes are variable in Cyclura and scale with female size (Cyclura reproductive ecology literature; IUCN species notes).

Diet: primarily herbivorous-leaves, flowers, and fruits dominate; opportunistic animal matter (e.g., insects/carrion) may be taken, especially by juveniles (Cyclura diet studies; IUCN notes).

Conservation turnaround: the wild population fell to only a few dozen animals by the early 2000s, then rebounded through head-starting and reintroductions by the Blue Iguana Recovery Programme to well over 1,000 free-ranging iguanas in protected areas in recent years (program reports; IUCN/partner updates).

Unique Adaptations

  • Robust 'rock iguana' build: deep skull and strong jaw musculature for cropping tough, fibrous island vegetation; a hallmark of Cyclura.
  • Spiny dorsal crest and tail: enlarged dorsal scales plus a powerful tail aid defense and intimidation; tail can be used as a whip in close encounters.
  • Salt-handling physiology: like many iguanids, Cyclura possess specialized glands to help excrete excess salts from a plant-based diet in coastal environments (comparative iguanid physiology).
  • Color signaling: the species' blue/gray tones-especially in adult males-enhance visual communication in open, rocky habitats, supporting dominance and mate attraction.
  • Island-endemic ecology: behavior and life history are tuned to Grand Cayman's seasonal resources (fruiting/flowering pulses), with opportunistic feeding and strong use of refuges.

Interesting Behaviors

  • Diurnal thermoregulation: emerges to bask for rapid morning warm-up, then alternates sun/shade to keep body temperature in an active range typical of large iguanids.
  • Male territoriality: mature males defend prime feeding/basking areas; disputes include head-bobs, push-ups, dewlap extension, lateral body flattening, and short chases (classic iguanid display repertoire).
  • Burrow use: shelters in rock crevices and burrows for nightly refuge and during extremes; females excavate nest tunnels in suitable soils during the breeding season.
  • Site fidelity: adults tend to maintain stable home areas when habitat is intact, a trait common in Cyclura and useful for monitoring reintroduced individuals.
  • Seasonal breeding: courtship and mating peak seasonally; males intensify display behavior and guarding of receptive females during that period.

Cultural Significance

The Blue Iguana (Cyclura lewisi) is a native flagship and symbol of Grand Cayman's natural heritage. Its recovery is tied to the National Trust and Blue Iguana Programme and island conservation. It is used in nature education, ecotourism, and local pride to protect endemics from predators and habitat loss.

Myths & Legends

Name origin: the English word "iguana" entered English via Spanish and ultimately derives from a Taino (Arawakan) word used in the Caribbean.

Not a folk tale: colonial Caribbean accounts said iguanas were an important food. On Cayman, Blue Iguana (Cyclura lewisi) were once hunted and common before legal protection made them a celebrated endemic.

Cyclura lewisi was named as a separate West Indian rock iguana in 1940 by Chapman Grant. The species name honors a collector named Lewis and is part of the island's natural history.

Conservation Status

EN Endangered

Facing a very high risk of extinction in the wild.

Population Increasing

Protected Under

  • CITES Appendix I (Cyclura spp. listed; international commercial trade effectively prohibited)
  • Cayman Islands National Conservation framework (species legally protected; killing/harassment/capture restricted and permits required)
  • Protected-area/site management and recovery actions on Grand Cayman (e.g., managed reserves and the Blue Iguana Recovery Programme with captive breeding, head-starting, and reintroductions)

Life Cycle

Birth 15 hatchlings
Lifespan 30 years

Lifespan

In the Wild
15–40 years
In Captivity
20–60 years

Reproduction

Mating System Polygyny
Social Structure Solitary
Breeding Pattern Seasonal
Fertilization Internal Fertilization
Birth Type Internal_fertilization

Blue Iguana (Cyclura lewisi) breeds seasonally (May–June) with polygyny: territorial males mate with several females after displays and fights. Females nest alone, lay one clutch (1–21, often mid‑teens), incubate ~65–90 days; hatchlings are independent with no parental care.

Behavior & Ecology

Social Solitary Group: 1
Activity Diurnal, Matutinal, Vespertine
Diet Omnivore Ripe fruits (notably sea grape, Coccoloba uvifera, when in season)

Temperament

Primarily wary/avoidant of close approach in the wild; relies on crypsis and retreat to rock crevices or burrows when disturbed (IUCN Cyclura lewisi account).
Territorial and can be overtly aggressive during the breeding season-males display, chase, and fight (biting/tail-whipping) to defend access to females and key habitat features (IUCN Cyclura lewisi account; Cyclura natural history in iguana conservation literature).
Females can become more defensive around nesting sites and immediately post-oviposition; aggression is usually context-dependent rather than constant.
Blue Iguana (Cyclura lewisi) are mostly solitary and keep territories. They meet more during mating season and at nesting sites. Their fighting and friendliness toward neighbors change with local numbers and food.

Communication

Hissing/exhalation and occasional forceful breathing sounds during threat/handling; otherwise generally low-vocal Reported in Cyclura husbandry/field notes; consistent with iguanid behavior descriptions in herpetological literature
Visual displays: head-bobs, body posturing, lateral compression to appear larger, dewlap extension, and push-up style displays used in territorial and courtship contexts Described for Cyclura spp. and applied to C. lewisi in conservation/field summaries; e.g., IUCN Cyclura lewisi account; iguanid display behavior literature such as Carpenter & Ferguson's classic lizard communication syntheses
Tactile/aggressive behaviors: charging, biting, and tail-whipping during escalated male-male conflicts and close-range disputes Reported for Cyclura spp. including Blue Iguana in recovery-program and field summaries
Chemical cues: scent marking/chemical signaling via femoral pores and substrate rubbing is used for territorial and reproductive information General for Cyclura/Iguanidae; referenced in iguana biology/conservation treatments and husbandry manuals; applied to C. lewisi in management observations
Spatial signaling: use of prominent basking/lookout positions and repeated patrol routes that advertise occupancy to conspecifics Territorial spacing behavior described for Cyclura in field-based accounts, including Blue Iguana conservation monitoring

Habitat

Biomes:
Tropical Dry Forest Savanna
Terrain:
Island Coastal Karst Rocky Sandy
Elevation: Up to 59 ft 1 in

Ecological Role

Large-bodied native herbivore/omnivore in Grand Cayman's dry-forest and coastal scrub ecosystems; functions mainly as a browser and fruit consumer with secondary opportunistic predation/scavenging.

Seed dispersal (endozoochory of consumed fruits) and potential enhancement of germination via gut passage Vegetation shaping through selective browsing on leaves/shoots/flowers Nutrient cycling via deposition of feces (and occasional carrion consumption) Soil disturbance/microhabitat creation associated with terrestrial movement and refuge/burrow use (benefiting some invertebrates and plants)

Diet Details

Main Prey:
Insects Land snails and other small terrestrial invertebrates Terrestrial crabs Bird eggs and nestlings Carrion
Other Foods:
Leaves and young shoots of native shrubs and trees Flowers Fruits Prickly-pear cactus Sea grape Native coastal dry-forest plant material

Human Interaction

Domestication Status

Wild

Cyclura lewisi (Blue Iguana) is a wild, not domesticated rock iguana from Grand Cayman. People keep it mainly for conservation, education, and a few private collections, not as pets. It nearly went extinct from habitat loss, predators, and killing. The Blue Iguana Recovery Programme used captive breeding, head-starting, and releases to rebuild the population.

Danger Level

Moderate
  • Bite and crushing jaw injury risk if handled or cornered (large adult iguanas can inflict deep lacerations)
  • Tail-whip strikes causing bruises/eye injury risk at close range
  • Scratch injuries from claws during restraint
  • Zoonotic risk common to reptiles (e.g., Salmonella) from contact with feces or contaminated surfaces-requires strict hygiene

As a Pet

Not Suitable as Pet

Legality: Blue Iguana (Cyclura lewisi) is not usually a good pet and is often protected. International trade is tightly controlled under CITES, and moves need CITES papers; many places require permits even for captive-bred animals.

Care Level: Expert Only

Purchase Cost: $2,000 - $10,000
Lifetime Cost: $15,000 - $50,000

Economic Value

Uses:
Conservation employment and program funding Ecotourism and wildlife viewing Education/outreach (zoos, visitor centers) Scientific research value (island restoration, reintroduction biology)
Products:
  • Non-consumptive value (ecotourism/education); no legitimate consumptive products are associated with the species due to protection and trade controls

Relationships

Related Species 9

Cuban rock iguana Cyclura nubila Shared Genus
Bahamian rock iguanas Cyclura cychlura Shared Genus
Anegada rock iguana Cyclura pinguis Shared Genus
Jamaican iguana
Jamaican iguana Cyclura collei Shared Genus
Rhinoceros iguana Cyclura cornuta Shared Genus
Northern Bahamian rock iguana Cyclura rileyi Shared Genus
Turks and Caicos rock iguana Cyclura carinata Shared Genus
Green iguana Iguana iguana Shared Family
Lesser Antillean iguana Iguana delicatissima Shared Family

Ecological Equivalents 4

Animals that fill a similar ecological role in their ecosystem

Rhinoceros iguana Cyclura cornuta Ecologically similar large, primarily terrestrial rock iguana: diurnal basker, strong site fidelity to rocky/limestone terrain, and largely herbivorous (leaves, flowers, fruits) with opportunistic omnivory, similar to the Blue Iguana's ecology on xeric limestone scrub and forest edges.
Cuban rock iguana Cyclura nubila Occupies dry coastal scrub and rocky habitats in the Greater Antilles, with a similar feeding strategy (predominantly herbivorous with opportunistic animal matter), comparable use of refuges (rock crevices and burrows), and similar basking behavior.
Green iguana Iguana iguana Shares diurnal thermoregulation and a primarily herbivorous diet, and can overlap in disturbed Caribbean habitats. Differs by being more arboreal and strongly associated with riparian and forest canopy, whereas blue iguanas are characteristically more terrestrial on limestone substrates.
Black spiny-tailed iguana Ctenosaura similis A large, ground-using iguanian lizard of dry tropical habitats that relies on basking, rapid sprinting to cover, and refuge use in rocky areas and burrows. Niche parallels include omnivory with substantial plant intake and similar exposure to mammalian predators in human-modified landscapes.

The Blue iguana is a species of lizard that is currently endangered. It is native to the island of Grand Cayman.

With this lizard’s articulated toes, it can dig up things quickly and climb trees. While a mature male can be of dark grey to turquoise color, the female is more of olive green to pale blue.

Younger blue iguanas feature much different coloring that is much darker, featuring a dark brown or green hue with a darker banding uniformly. The adults can change their color to blue when they are around other iguanas to mark their territories, but they often prefer to stay on the ground. Male blue iguanas are larger than females and have more prominent dorsal crests. The axanthic blue iguanas, however, are only 10 to 14 inches in size.

Blue iguana infographic

5 Incredible Blue Iguana Facts!

Even with the many changes that other reptile species have, the blue iguana has many interesting facts that help it to stand out. Here are just a few traits that the blue iguanas exude.

  • Blue iguanas are axanthic, which means that they don’t have any blue or yellow pigment in their skin. Instead, they can only create grey, black, and brown in their complexion.
  • These iguanas are rather small, only reaching a maximum of 14 inches in length.
  • Blue iguanas don’t typically enjoy living together, opting for a more solitary life. Still, they will seek out a mate when breeding needs to occur.
  • When it comes to bedtime, the blue iguana prefers to sleep in the darkness of night, much like other iguana species.
  • Blue iguanas are incredibly territorial, showing aggression towards any threats to their habitat as young as just a few months old.
Grand Cayman Blue Iguana. Cyclura lewisi is an endangered species and is native to the Cayman islands.

Cyclura lewisi aka Grand Cayman Blue Iguana is an endangered species and is native to the Cayman Islands.

Scientific Name

The blue iguanas go by the scientific name Cyclura lewisi. They belong to the kingdom Animalia and phylum Chordata. Their class is called Reptilia, and the order is called Squamata. The suborder is Iguania, and the family is called Iguanidae. The genus is called Cyclura, and the species is called C. lewisi.

Appearance

The blue iguanas usually have skin that ranges from dusky blue to grey. They have crossbands over their bodies. The bands, however, are barely visible. The mature male’s skin color ranges from dark grey to turquoise blue while that of the females is more olive green to pale blue. Meanwhile, the young blue iguanas are uniformly dark brown or green.

The coloration gives a great camouflage advantage to these lizards. During the mating season, these lizards become a brighter blue. Like many other species, the vibrant color is more prominent and pronounced in males than in females. Males are also known to be bigger than females. They have more prominent crests as well as larger femoral pores located on their thighs, which release pheromones.

The axanthic blue iguanas are usually about 20 to 30 inches in size and weigh about 30 pounds. However, the baby blue iguanas are only 10 to 14 inches in size.

Extremely Rare Blue Iguana (Cyclura lewisi) is protected in the Queen Elizabeth II Botanic Park, where you can find the real natural habitat of this surprising creature.

The blue iguanas usually have skin that ranges from dusky blue to grey. They have crossbands over their bodies but these are barely visible.

Behavior

These Iguanas are usually solitary and come together only to breed. They are known to be active during the day and usually enjoy sleeping through the night. They love sleeping in tree cavities as well as rock holes. These lizards are terrestrial which means that they love staying on the ground, but they can climb trees that are 15 feet and higher. The younger blue iguanas are more arboreal.

Even though these lizards are known to be solitary, in captivity, they can turn pretty aggressive toward each other from an incredibly young age. They are known to get bolder and more visible as they grow in age.

The female iguanas live a solitary life most of the year. They stay homebound, close to their favorite rock holes. The females are known to defend a small territory including places to feed as well as bask. No other adult female iguanas are allowed in their territories. The message of staying away is communicated through vigorous head bobbing. If that doesn’t work, the intruder is then attacked.

The males on the other hand are less tied to one single place and often sleep in alternative holes that are usually scattered across a much larger territory. During the non-breeding season, the males are lazy and get up late. They eat a lot during this time and mask motionless for hours.

Blue iguanas can make great pets. They are sold at high prices, sometimes up to $1000. They are one of the most popular lizards that are kept as pets. However, they require a lot of attention and human care. Under human care, they can live for as many as 69 years. Usually, otherwise, their lifespan is about 25 to 40 years.

Habitat

These iguanas are native to the island of Grand Cayman. They love sleeping in tree cavities and rock holes. They prefer staying in dry, rocky forests that are situated in coastal areas. The rocky forests that they prefer may contain cacti and other plants with thorns.

Apart from that, these lizards can also be found in semi-deciduous forests, scrub woodlands, tropical forests as well as dry-to-subtropical forests. Not only that, but the blue iguanas can adapt to manmade habitats, as well.

grand-cayman-blue-iguana-eating-a-flower

Grand Cayman blue iguanas enjoy eating flowers.

Diet

These iguanas are primarily herbivorous and mostly feed on stems and leaves. They also eat fruits and flowers. However, occasionally, you could spot these lizards feeding on excrement, fungi, soil as well as insects.

Reports suggest that at some zoos, these lizards are fed carrots, sweet potatoes, leafy green vegetables, and herbivorous pellets. They may also rarely feed on crabs and slugs.

Predators and Threats

These iguanas face a predation threat from feral animals. Apart from that, free-roaming dogs and cats also hunt these lizards down. They are known to kill and prey on both adults as well as young iguanas.

The baby blue iguanas and the hatchlings face predation threats from Norway rats. Human activities like deforestation, industrialization, and urbanization also pose a threat to these iguana lizards.

A baby exotic blue iguana in a person's hand.

A baby blue iguana sits in a person’s hand. Blue Iguanas can live for 25 to 40 years usually.

Reproduction and Life Cycle

These iguanas are known to indulge in mating sessions from May through June. The male iguanas court the females by head bobs. After that, the males circle the females and grasp the nape of her neck.

Forty days after mating, the females dig out a nest in earth pockets. These nests in the ground are exposed to the sun. The female then lays a clutch of eggs there. The clutch can vary anywhere between one to 21 eggs. The eggs are usually laid in June or July.

Researchers say that the nests maintain a temperature of 32 degrees Celsius throughout the incubation period. The incubation period ranges from 65 to 90 days. The baby iguanas become aggressively territorial when they are about three months old. They are known to reach sexual maturity at the age of four in captivity.

Blue Iguanas are said to live for 25 to 40 years usually. However, in one case, a male iguana that was kept by people survived for about 69 years in total.

Blue Iguana isolated on blue background.

Though they are on the endangered species list, blue iguanas are making strides to grow in population.

Population

The IUCN Red List says that there are about 443 mature blue iguanas in the world. This species is currently categorized as endangered on the IUCN Red List. However, it has been said that the population numbers are now increasing in the world.

It has also been said that by 2003, fewer than 15 blue iguanas had remained in the wild, and by the first decade of the 21st century, the wild population was said to be extinct.

Evolution and Origin

In 1938, Charles Bernard Lewis from the Institute of Jamaica joined a Cayman Islands expedition. He obtained two blue iguanas, a male and a female. In 1940, the blue iguana was formally described as C. macleayi lewisi, though it was reclassified as C. nubila lewisi in 1975, making it a subspecies of the Cuban iguana. Changing this mistake, the blue iguana was finally reclassified as a distinct species in 2004.

Not much else is known about the evolution and origins of this lizard, other than it is indigenous to the Cayman Islands.

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Sources

  1. Animalia / Accessed May 26, 2021
  2. Smithsonian's National Zoo & Conservation Biology Institute / Accessed May 26, 2021
  3. Wikipedia / Accessed May 26, 2021
Bethany McKay

About the Author

Bethany McKay

Bethany is a professional copywriter and editor, working with newspapers, small businesses, Fortune 500 companies, and everything in-between. She graduated from Penn State University with degrees in journalism and international studies. She loves her cat, Maggie, and has had numerous pets over the years, including guinea pigs, hermit crabs, fish, and a red-eared slider turtle. She lives among farmlands in southcentral PA and enjoys gardening, cooking, reading, and sewing.
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Blue Iguana FAQs (Frequently Asked Questions)

Blue iguanas are primarily herbivorous in nature and mostly feed on stems and leaves. They also eat fruits and flowers. Occasionally, they also eat insects, soil, crabs as well as slugs.