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New giant tortoise species discovered in the Galapagos Islands

Perhaps no better case can be made for adaptation than the marine iguana! Just about everything about this ancient lizard points to evolution at its finest.

Fact Sheet

  • Species Name: Amblyrhynchus cristatus
  • Size at maturity: 4 to 5 ft
  • Weight: 1 to 3.3 lbs
  • Population: 200,000-300,000 (on the rise)
  • Status: Vulnerable
  • Range: Endemic to Galapagos Islands
  • Threats: El Niño (atmospheric event that wipes out much of their food source); Cats (introduced by man); Hawks, herons, birds (only a threat to young iguanas)
  • Lifespan: 5-12 years

Appearance: Black, red (at maturity) scaly skin

Conservation Efforts

While their population is booming at around 200,000-300,000, the National Park is still wary of events like El Niño that could kill off huge portions of the population. Careful efforts are taken to not disturb their natural habitats.


The marine iguana, endemic to the Galapagos Islands, is the only seagoing lizard in the world. While other iguanas can swim, the marine iguana is especially equipped to spend much of its time grazing on algae many meters below the surface.

  • Sharp claws: These help the iguanas grip the lava rock under the water while they are grazing.
  • Black skin: This helps absorb the heat of the sun to keep them warm when they dive deep to feed on algae.
  • Salt glands: When they surface after feeding, they can expel any excess salt consumed through these special glands above their nose.
  • Paddle tail: As the only seafaring lizard, their tails have evolved to be perfect paddles for them as they swim and dive.
  • Ability to digest seaweed: Unlike most species, they are able to digest seaweed, and it actually forms a large part of their diet.
  • Holding their breath: Marine iguanas can stay underwater while feeding for up to 45 minutes.
  • Great divers: At times when there is not a lot of algae or seaweed near the surface, marine iguanas can dive to impressive depths of 100 feet.
marine iguana - galapagos