Card #065 · Reptiles
Marine iguana
Amblyrhynchus cristatus
Rare VU · Vulnerable
Field notes
- Classification
- Order Squamata · Family Iguanidae
- Range
- Galápagos Islands, Ecuador
- Size
- Up to ~1.3 m (4.3 ft)
- Weight
- Up to 12 kg (26 lb)
- Lifespan
- ~12 yrs, to 60
- Diet
- Red and green algae
Most Notable
When El Niño kills off the algae beds, an adult can shrink. Bone is resorbed along with soft tissue, taking up to a fifth of its length away, and it grows back when the food returns.
No other lizard makes its living in the sea. Big males dive to 30 m and stay under for half an hour, cropping algae off the rock; everything else grazes the intertidal at low tide. The salt that comes with the meal is filtered out by glands above the nose and sneezed away.
Size is set by which island you are born on. Adult males top out around 12 kg on southern Isabela and around 1 kg on Genovesa, and eleven subspecies are now assessed separately across the archipelago.
Darwin met them in 1835 and was unimpressed: 'It is a hideous-looking creature, of a dirty black colour, stupid, and sluggish in its movements.'
Feral cats, rats, dogs and pigs now reach roughly a third of the population, and the El Niño events that starve the algae are forecast to intensify.
Range: Rocky coasts of the Galápagos Islands, Ecuador.