Marine Iguana

When Charles Darwin first arrived in the Galapagos Islands in September 1835 and saw the shoreline covered in Marine Iguanas [Amblyrhynchus cristatus], he was repulsed by them, calling them “disgusting, clumsy lizards”, and then famously referring to them in his journal as “imps of darkness”.

Punta Espinosa, Fernandina (Narborough) Island  [nominate, ssp.cristatus]


I'd agree that you'd be hard pushed to call them attractive, but they are interesting and, without doubt, are one of the most iconic creatures that you'll encounter if you visit Galapagos. Personally I think they deserve a better press, which is why I've put together this short article accompanied by a few of my favourite photos. 

Puerto Egas, Santiago (James) Island  [ssp.mertensi]


It's true that just about every rocky shoreline around Galapagos is home to this endemic species, which is the only sea-going lizard in the world. They are extraordinary animals that live on the land, but feed in the sea, which led Darwin to theorise that they were able to adapt their ability to swim and dive for food to suit their habitat. So, despite his revulsion of them, Marine Iguanas ended up being a key factor in compiling his ‘theory of evolution’. 

Tagus Cove, Isabela Island  [ssp.albemarlensis]


They feed by grazing on a variety of seaweed from exposed rocks, sub-tidal pools, or from the sea itself where they can dive down to a depth of around 9m. Whilst this totally unique way of feeding provides them with an abundant source of food, they cannot withstand the cold temperatures of the sea for too long, so must spend a lot of time on land warming up.  In fact, most of the Marine Iguanas we saw were just laying on rocks soaking up the sun.

Puerto Suarez, Española (Hood) Island  [ssp.venustissimus]


Their seaweed diet results in a high intake of salt, which they have to spit out through their nostrils. A disgusting habit that is accompanied by a wet snort, which is the only sound they make.

Punta Espinosa, Fernandina (Narborough) Island  [nominate, ssp.cristatus]


Whilst they are clumsy when climbing over rocks, or indeed each other, they are graceful swimmers. They have a laterally flattened tail and spiky dorsal fin, which aids propulsion in the water, and long sharp claws that allow them to hold onto rocks in strong currents.

Puerto Egas, Santiago (James) Island  [ssp.mertensi]


There are seven races, or subspecies, of Marine Iguana that vary in both size and colour from island to island - the largest are on northern Isabela [ssp.albemarlensis], which grow up to 1.3m in length; the smallest on Genovesa [ssp.nanus], which are half that size; and the most brightly coloured on Española [ssp.venustissimus]. They are largely black or dark grey, although the males acquire a red or red-green tinge during the mating season.

Punta Moreno, Isabela Island  [ssp.albemarlensis]

Puerto Suarez, Española (Hood) Island  [ssp.venustissimus]


They can be found in very large concentrations with hundreds if not thousands of individuals together in some areas. The total population throughout the islands is estimated to be around 250,000. Despite the numbers seen, you had to look closely to find one with its eyes open. But, because there really were so many, I was able to accumulate quite a lot of different shots during the ten days we travelled round the islands and ended up with a good variety of photos including quite a few of them feeding.

Puerto Egas, Santiago (James) Island  [ssp.mertensi]


Their conservation status is categorised as 'vulnerable' on the IUCN Red List of 'threatened species'.

Puerto Suarez, Española (Hood) Island  [ssp.venustissimus]

Iguanas, Lizards & Geckos

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