Marine Iguana

Marine Iguana

Galápagos marine iguana, Galapagos Marine iguana, Fernandina Marine iguana, Sea iguana, Saltwater iguana

Kingdom
Phylum
Subphylum
Class
Order
Family
SPECIES
Amblyrhynchus cristatus
Population size
210,000
Life Span
30 years
Top speed
35
22
km/hmph
km/h mph 
Weight
10
22
kglbs
kg lbs 
Length
50-100
19.7-39.4
cminch
cm inch 

The Marine iguana (Amblyrhynchus cristatus) is a species of iguana found only on the Galápagos Islands (Ecuador). Unique among modern lizards, it is a marine reptile that has the ability to forage in the sea for algae, which makes up almost all of its diet. Marine iguanas are the only extant lizard that spends time in a marine environment. Large males are able to dive to find this food source, while females and smaller males feed during low tide in the intertidal zone.

Di

Diurnal

He

Herbivore

Al

Algivore

Se

Semiaquatic

Ov

Oviparous

Pr

Precocial

Te

Territorial

Na

Natatorial

Po

Polygyny

Hi

Highly social

Co

Colonial

No

Not a migrant

M

starts with

Appearance

Marine iguanas are usually black or gray but during the breeding period, adult males gain green and red coloration. The dark skin pigment helps in shielding the animals from ultraviolet rays and also helps to warm their bodies. Young iguanas have a dorsal stripe of a lighter color. Their dorsal scales are triangular in shape and they have a long tail which propels them through the water when swimming. They are often encrusted with a white substance, which mainly consists of excess salt excreted via their nasal glands.

Video

Distribution

Geography

Continents
Countries
Islands
Biogeographical realms
WWF Biomes

Marine iguanas live in the Galapagos Islands, an archipelago near the South American coast. They inhabit rocky shores in the intertidal zone, but can also be seen in marshes, mangrove swamps, and beaches.

Marine Iguana habitat map

Climate zones

Marine Iguana habitat map
Marine Iguana
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Habits and Lifestyle

Marine iguanas are diurnal. When not hunting in the sea for food, they bask on rocks, often several thousand individuals together in the same area. They live in colonies. Before it can feed, the marine iguana must increase its body temperature to approximately 36°C. Its temperature can drop as much as 10°C when it is in the ocean. In order to regulate its body temperature, an iguana must spend long periods of time basking in the sun. With a low body temperature it will move more sluggishly, and so is then at greater risk from predators. To combat this vulnerability, the iguana acts in a highly aggressive way to bluff its way out of danger.

Seasonal behavior

Diet and Nutrition

Marine iguanas mostly eat marine algae. Larger iguanas will dive into the sea in order to forage, sometimes diving as deep as 12 m (39 ft) and staying submerged for more than an hour. Under normal circumstances, they make shallow dives, usually lasting around 10 minutes. The smaller iguanas keep out of the water, feeding instead on algae on rocks in the tidal area.

Mating Habits

MATING BEHAVIOR
REPRODUCTION SEASON
December-March
PREGNANCY DURATION
89-120 days
BABY CARRYING
1-6 eggs
INDEPENDENT AGE
at birth
BABY NAME
Hatchling

Marine iguanas are polygynous. Males fight aggressively to secure a mate, and females select them based on their body size, preferring larger individuals. Large males defend territories for up to three months during the breeding season, and in this period they sometimes fight other males. Medium-sized males roam areas near the territories of large males or walk along beaches looking for females, while small "sneaky" males may enter the territories of large males. The breeding season is from December to March and the nesting season is from January to April. Females go inland to lay 1 to 6 eggs in a burrow of sand, along with thousands of others nesting in the same area, due to suitable sites being scarce. They will defend their burrow for a few days before leaving the eggs to incubate, which takes 89 to 120 days. Upon hatching, the baby iguanas dig themselves out from their nest and move down to the intertidal zone, where they start feeding. Females become reproductively mature at 3 to 5 years of age, and males at 6 to 8 years.

Population

Population threats

The periodic El Niño events reduce the cold water needed for algae to grow and this can drastically reduce the Marine iguana population, on some islands by as much as 90%. Introduced predators, to which iguanas have little or no protection, include animals such as pigs, dogs, cats, and rats. Dogs may take adult Marine iguanas, while the others may feed on their young or eggs. This inhibits reproduction and the long-term survival of the species. Introduced predators represent a major problem on the islands of Santa Cruz, Santiago, Isabela, Floreana, and San Cristóbal where very few Marine iguana hatchlings survive. Occasional oil spills in the region also present a threat.

Population number

According to IUCN Red List, the total population size of the Marine iguana is below 210,000 individuals. Currently, this species is classified as Vulnerable (VU) on the IUCN Red List, and its numbers are decreasing.

Fun Facts for Kids

  • The saw-like ridge of spines on the iguana's back not only gives a sinister appearance but also helps regulate its body temperature as the iguana basks in the sun
  • Marine iguanas sneeze. They do this because when eating, they swallow saltwater, and once back on land they have to get rid of the salt. Their salt-excreting glands help them do this, and, as they sneeze, the saltwater comes out.
  • Marine iguanas have a good relationship with mockingbirds because when Galapagos hawks are hunting, mockingbirds sound their distinctive cry, which some iguanas have learned means danger, and so they run for cover.
  • Some marine iguanas grow very large because of the abundance of food in their environment. If there is a plentiful supply of underwater algae, this means they can grow much bigger than those iguanas living where there is less food. Whichever island they live on, being the biggest animal is what they strive for. The females prefer the biggest males, and the best eggs are laid by the biggest females.
  • An adult iguana is able to stay underwater for as long as 45 minutes.
  • An iguana can grow another tail if it is cut off. Often they will break off their own tail to escape a predator when they have been caught.
  • Iguanas are able to stop their heart from beating for as long as one minute.

Coloring Pages

References

1. Marine Iguana Wikipedia article - https://en.wikipedia.org/wiki/Marine_iguana
2. Marine Iguana on The IUCN Red List site - http://www.iucnredlist.org/details/1086/0

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