Marine iguana



Marine iguanas are somewhat large lizards living only in the Galapagos. Unlike other iguanas, they are usually blackish in color instead of green. They can also have many other colors though including brown, yellow, white, gray, and even pink! The marine iguana pictured below is an extreme example of the pink that can be found on these lizards. They are definitely diverse creatures! Marine iguanas are recognizable by their pyramid-shaped dorsal scales. The dorsal scales are what you can see coming out of the back of their head and down to the base of the tail. They are distinguishable from land iguanas by the shape of their snout. Marine iguanas have short, blunt snouts while other iguanas have longer, pointier snouts. These lizards have long curved claws that help them grip onto the rock and keep them from slipping. One of the other names this iguana has is the sea iguana. There are six subspecies of sea iguanas. The main differences between the subspecies are the islands on which they live.



Marine iguanas can grow to be quite large. They can be up to five feet (1.5 m) long, with the males slightly longer than the females. Almost half of this length can be from the lizard’s tail! Most of these iguanas are much smaller than the size I just mentioned, and they are normally only half this long. Males are just 2.5 feet (.75 m) long on average, and the females are usually only about 2 feet (.6 m) long. Although they are somewhat large, marine iguanas are very light. Their average weight is thought to be just 3.3 pounds (1.5 kg) for males with females being just half that much.

Diet and feeding

Marine iguanas are completely herbivorous even though they look like predators. Their main food is algae, and they feed on almost nothing else. Algae is available most places where these iguanas live, and where they feed depends on their size. The water around the Galapagos Islands, where these iguanas live, can be quite cold even though it is in a tropical area. Most of the iguanas cannot survive staying in the water long because they will become too cold. Small iguanas do not hold their heat in as well as the larger ones do. The small marine iguanas rarely go into the water, and eat mainly algae that grows either on the rocks or on the surface of the ocean so they don’t need to stay in the water long. Ones that are larger can dive in shallow waters up to about 16 feet (5 m) deep. The largest sea iguanas can survive the cold temperatures for several minutes and will feed in waters up to 82 feet (25 m) deep! They have a distinct advantage here as there is not as much competition for food at this depth.

There is one dangerous thing about land animals feeding in the ocean, and that is the salt content they inadvertently consume with their food. Marine iguanas do not have gills to process the saltwater as fish do, but they still have a way to keep their body’s salt content from becoming dangerously high. When they have been in the ocean consuming the salt water with their food, they excrete the the salt in the form of crystals in their nostrils. When there becomes too much salt in their nose, they simply sneeze, blowing the salt out.

Habitat and range

It probably is not very hard to figure out this iguana’s habitat and range – at least generally – based on what I have already said. Marine iguanas live exclusively on the Galapagos Islands off the coast of South America. The habitat they live in is typically the rocky coasts not far above sea level. They do sometimes climb the volcanic rock to a height of up to 262 feet (80 m). These iguanas live in colonies.

Status and threats

The IUCN Redlist has classified the marine iguana as ‘Vulnerable.’ Despite being so large for lizards, they do have many predators, albeit mostly non-native predators that consume the young and eggs. These include rats, wild dogs, and wild cats. These introduced predators are the main animal threats on the sea iguanas, but they are also threatened by the native Galapagos hawk. Habitat destruction is not a large threat, but pollution is. Oil spills are one of this animal’s worst man-made threats. These and other marine pollutants destroy foraging areas. In a 2001 oil spill about 15,000 marine iguanas on one island alone died.


The mating season for these animals runs from January to April depending on which island they are on. Although the mating season occurs every year, most individuals usually mate only every other year. Marine iguanas are very energy efficient when it comes to protecting their territory. The males do not fight, only bite at each other. Their territories contain harems of multiple females. Females chose their own mate based on how big and strong he looks, but losing territory is a sign of weakness that may cause a female to move elsewhere. After mating, the female waits about one month before laying the eggs. They only lay one to six eggs each. Theses eggs are incubated for about three months in a nest dug in sand and volcanic ash. Marine iguana nests can be up to 32 inches (81 cm) deep. For the first few days of incubation, the female sea iguana guards the eggs, but she leaves later.

When the young hatch, they have no parents there to take care of them, and they look and act just like miniatures of the adults. Females are ready to mate between three and five years of age; males are not ready until they are between six and eight years old. In the wild, marine iguanas can live up to 12 years.

Don’t forget to scroll down and comment your guess about what the next animal is!



Photo credits:

  • Marine iguana – Diego Dalso
  • Pink marine iguana – Benjamint444
  • Mystery animal – Jerzystrzelecki

One Response

  1. Charis Dwire
    Charis Dwire at |

    It’s some sort of seal. Is it a leopard seal?

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