How Are Marine Iguanas Different from Other Iguanas?

Get to know some of the key differences between the land-dwelling iguanas we all know and their water-loving cousins of the Galapagos Islands.

Nov 13, 2023By Caitlin Ross
how are marine iguanas different from other iguanas

A lizard is a lizard, right? Certainly not when it comes to iguanas! There are over 35 recognized species of iguana, each of them unique. However, the real differences come in when you compare land iguanas to marine iguanas - yes, there are ocean-dwelling reptiles, too! Keep reading to learn about them and how they differ from the iguanas you’re familiar with.


green iguana
Image credit: iNaturalist

First of all, let’s take a moment to recognize that iguanas aren’t the most charming creatures to look at, but that doesn’t make their appearances any less interesting or worth noting!

When it comes to comparing land and sea iguanas, one of the most noticeable differences is their size. Land iguanas are, on average, significantly larger, reaching up to six feet in length, while marine iguanas only grow to be about four feet long.

Marine iguanas have blunter snouts and webbed feet, which are adaptations that have developed to accommodate their island lifestyles. The reptiles also differ in color - however, every species of iguana (land and sea) has unique coloration. Some marine iguanas are dark green or brown, whilst some others sport brighter red and even blue tones.


rainforest iguana
Image credit: Freepik

Of course, probably the most notable difference between land and sea iguanas is where they reside.

Land iguanas have an extensive range comprising of rainforests, deserts, rocky regions, swamps, and lowlands. Different species of iguana have different needs and preferences when it comes to where they rest, feed, and mate, so their habitats vary quite a bit. Of course, some iguanas are also kept as pets, which means their habitat is usually a well-maintained and monitored cage.

Marine iguanas, on the other hand, are unique in that they have adapted to an ocean environment. They’re found exclusively in the Galapagos Islands, and while they’re excellent swimmers, they still spend most of their time on land, basking in the sun. However, the water is where these lizards find their food.

Feeding Habits

marine iguana eating
Image credit: bioGraphic

Another unique attribute is that marine iguanas feed primarily on red and green algae found on the rocks in the ocean. Most of these reptiles prefer to feed in the shallow waters. However, the stronger (and braver) individuals have no trouble venturing into the deep, diving as far as 65 feet below the surface. They use their strong claws to help them cling to the rocks and their sharp teeth to scrape the algae from the rocks.

As already mentioned, land iguanas come in many different forms and have different habitats, behaviors, and diets. That being said, the typical meal for any iguana is going to consist of foliage, flowers, and some fruit.

Both land and sea iguanas are predominantly herbivores but have been known to eat insects or even the eggs of smaller animals if their typical diet is out of reach. We might call them flexitarians - but they prefer to stay on the side of the greens.


marine iguana sneezing
Image credit: X

When it comes to adapting to one’s environment, marine iguanas take the cake. Scientists believe that many, many, many years ago, land-dwelling iguanas must have floated out to sea, drifting away on logs until they eventually reached the Galapagos Islands. From there, they evolved and adapted to their environment, becoming the sea iguana we know today.

We’ve already mentioned the marine iguana's blunt snouts and sharp claws that allow them to feed. They’ve also developed webbed feet and a flattened tail, which help them swim and dive deep into the water.

However, perhaps their most remarkable adaptation is their salt glands. As sea reptiles, marine iguanas ingest a lot of unwanted salt. All this sodium can cause dehydration and even kidney trouble for these creatures, so their bodies have figured out a creative way to get rid of the excess. The sea salt is filtered from their blood and expelled from the salt glands at their nostrils in a great, dramatic sneeze - spraying salt all over to rid themselves of the sodium.

Threats and Conservation

iguana in cage
Image credit: PetHelpful

Unfortunately, iguanas are said to be among the world’s most endangered animals - and this applies to both land iguanas and sea iguanas.

Some species of land iguana have suffered habitat loss and struggle with the threat of new predators like dogs, feral cats, and even pigs. Their numbers are also greatly diminishing due to illegal hunting, increased contact with tourists, and the illegal pet trade. Considered an “exotic pet,” these lizards are often smuggled illegally across the world for the black market. While these reptiles make great pets, this illegal trade is a practice both dangerous and cruel.

Marine iguanas, on the other hand, have been suffering due to oil spills in their waters and periodic El Nino events that alter the temperature of the ocean and impact their food availability.

Both reptiles need awareness brought to their struggles and for conservation efforts to be made if we want to ensure their survival years into the future.

Caitlin Ross
By Caitlin Ross

Caitlin is an animal lover at heart with a passion for writing and sharing this love with the world. She’s a born and raised South African and grew up always surrounded by animals: more pets than she can count, and regularly adventuring with her family into the bush, where she feels most at peace with the wildlife in their natural habitat.