Marine Iguanas of Galapagos

When I set on a journey to Galapagos I was all about seeing those massive schools of hammerheads, but then I discovered all-new world down under and came back with so much more.

One of the most unique encounters was with marine iguanas while feeding in the shallow waters at Cabo Douglas (Douglas Cape) next to Fernandina island. Here they dive to a depth of 3–7m where the food is (algae), and they stay down for 5–10 minutes while feeding.

Adults can easily go down to 30m of depth and stay up to 1 hour if required.

Compared to our thrill of spending time with them, early visitors to the Galápagos Islands considered the marine iguanas ugly and disgusting :-)

For more reefs and marine life photos, take a look at my Marine Life gallery.

Marine Iguanas

Marine iguanas are the only truly marine lizards in the world. Juveniles and smaller individuals, in general, do not travel too far from the shore to feed. Adults can go further away and deeper.

They typically range from 12 to 56 cm for body length and have a tail from 17 to 84 cm long and this can vary by specific island. The adults are black for most of the year, however, the males change color during the mating season with different subspecies adopting different colorations. The juveniles are generally black, with a lighter dorsal stripe than the adults. 

Marine iguanas are a type of iguana that can be only found at Galapagos. Marine iguanas are herbivores and they have the ability, unique among modern lizards, to forage in the sea, making it a marine reptile.

They live in colonies onshore and go into the water only for feeding algae. Marine iguanas are not a very agile species on land, but they are excellent swimmers moving easily through the water as they feed on algae. Larger individuals go further out to sea and use their powerful claws to grip on to rocks in strong currents to feed, whilst the smaller ones stay inshore near rock pools, feeding on algae exposed at low tide.

Marine Iguana types

There are six very similar subspecies of marine iguanas, each from different islands. They vary in appearance between the different islands and several subspecies are recognized.

In one study, the largest was from western San Cristóbal Island, followed by those from Isabela, Floreana, eastern San Cristóbal (one named Godzilla), Fernandina and Santa Cruz. The smallest by far were from Genovesa (nanus), but this study did not include any marine iguanas from Wolf and Darwin Islands. The remaining island populations were of intermediate size. This difference in body size between islands is due to the amount of food available, which depends on sea temperature and algae growth.

In terms of color, near Española and Floreana they are most colorful — turning bright green and red; on Santa Cruz, they are red and black, and on Fernandina, they become dull green and brick red.

Cabo Douglas

Cabo (Cape) Douglas dive location is located on the north-west side of Fernandina Island. Fernandina is one of the central Galapagos islands and has an active volcano which has been subject to eruptions within the last ten years. The most recent volcanic eruption was in 2009.

Fernandina is one of the most unspoiled environments in the world and one of the few places in the Galapagos which has never suffered any kind of invasive species. Many of the animals on Fernandina exist only on the Galapagos Islands.

Marine iguanas have also evolved to survive on these islands making them completely distinctive to the region. The island is also home to a great number of sea lions, turtles, pelicans and Galapagos penguins. The dive sites at Cabo Douglas don’t cover a very large area but it holds the opportunity to see so many rare species that it is thrilling diving.

Here, we had an opportunity to see many of the Marine Iguanas feeding under the water. They were of different sizes and most adults. Once they are in the feeding mode, nothing can disturb them or scare away so the Close Focus Wide Angle (CFWA) shooting technique worked really well with the ability to really get close and personal.

Interesting Facts

1. Marine Iguanas are older then Galapagos islands themselves.

2. Charles Darwin described them as “hideous-looking” and “most disgusting, clumsy lizards.”

3. Highly threatened subspecies found only in the northeast of the oldest island of the archipelago, San Cristóbal, has been named “the Godzilla marine iguana” (Amblyrhynchus cristatus Godzilla), in honor of the fictional saurian monster Godzilla, which was in turn originally inspired by marine iguanas.