The color of the marine iguana can be pretty fascinating. A few people like Charles Darwin describe marine iguanas as black lizards thriving on the seas but actually marine iguanas aren't always black. While dorsal stripe color is taken by the young ones of marine iguanas the adults are grayish in color. Even though their colors are really dull, there's a reason for this dullness. These colors allow the marine iguanas to absorb the heat easily as they come out of the waters. Their diet is usually just the water algae present in the sea. Basking under the sun helps the marine iguanas to remove the left out salts from its nasal glands. Their faces of the marine iguanas usually appear white due to the salt content present in their bodies.
The color of the male matured iguanas depends on the ongoing season. Due to which they have a variety of colors. At their breeding season, the adult males appear teal green or even reddish brown in color. The ones in Santa Cruz appear to be red brick and black whereas those thriving in Fernandina have brick red and dull green color appearance. Like their colors, so do the sizes of these iguanas vary with island they house in. While the largest of them are present in the entire of Isabela and Fernandina of the Galapagos, the smallest of them are in Genovesa.
The marine iguanas cannot venture for a long time in the sea while in search of food or anything else due to their poikilothermic nature. That's the reason why they usually stick to swimming within the shallow areas of the island waters. Following their search for food, they go back to basking under the sun for warming themselves again. Marine iguanas are most easily hunted by their predators in the cold days as the cold affects the movement of the iguanas. But they do try protecting themselves by striking their tails up and biting the predators which they think is causing them danger. The whole breeding season of the marine iguanas is spent by mating with the other sex and also by protecting them over other males of their breed.
The iguanas have the ability to adapt their sizes according to the food availability at that time. At the time of the El Niño when the amount of water algae decreased, the iguanas actually reduced in their lengths to bring themselves to the food condition. Later as the food conditions began to come back to normal so did the size of the reptiles. These types of iguanas are slow compared to their relatives. Sometimes when they are taken as pets, dogs and cats emerge as their predators as the iguanas are really slow and too tamed.
The Ecuador government has brought about many laws to prevent the fall of the marine iguanas till date. To protect them against predators artificial nestling sites have been set up in the smaller islands.