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FERNANDINA ISLAND GALAPAGOS -
MARINE IGUANAS & SALLY LIGHTFOOT CRABS

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You have to watch your step on Fernandina Island. Covering the ground are lava flows and rocks that seem to move.

Photographing marine iguanas
Photographing marine iguanas
Photo © Barb & Ron Kroll

In reality, some of the "rocks" are licorice-black marine iguanas, which resemble miniature dinosaurs. The scientific name for marine iguanas is Amblyrhynchus cristatus.

Where is Fernandina Island?

Formerly called Narborough Island, Fernandina was one of our Galapagos cruise tours from M/Y Eric, an Ecoventura ship.

The westernmost Galapagos Island, Fernandina is separated from Isabela Island by the Bolivar Channel. Because it has the coldest water in the Galapagos, Bolivar Channel is a great place for whale watching. We spotted Bryde's and sei whales.

Don't step on the iguanas!

Stepping over marine iguana
Stepping over marine iguana
Photo © Barb & Ron Kroll

Before we started walking along the rocky black lava path, our Galapagos cruise guide, Yvonne Mortola, warned us to stay between trail markers.

"Marine iguanas lay eggs in the sand. Stay on the trail so you don't disturb their nests." Marine iguana eggs look like leathery, short fat sausages.

Even on the trails, we often didn't see the marine iguanas, sprawled motionless in confused heaps, until they snorted fine sprays of salt water out of their nostrils like squirt guns.

The result? An acrobatic dance, as we balanced precariously on one foot to avoid stepping on one marine iguana, only to find another one resting quietly beneath the other foot.

Marine iguana diet

Adult marine iguanas keep each other warm.
Adult marine iguanas keep each other warm.
Photo © Barb & Ron Kroll

Why are the marine iguanas on Fernandina Island larger than the ones we saw on Genovesa Island? Marine iguanas are the world's only sea lizards. They are vegetarian and eat only algae.

"The Cromwell Current is full of nutrients, which come to the surface and produce lots of algae," said Yvonne. At Genovesa, the water is warmer, with fewer nutrients and less algae, so the marine iguanas are smaller.

She explained that big male iguanas are strong swimmers, so they eat when they are hungry, even when the water is rough. Making near-suicidal dives five to 50 feet (1.5 to 15 meters) deep into the cold water, they cling with their strong claws to rocks so the current doesn't carry them away.

Before their muscles seize up from the frigid water, they swim to the coast and lie down spread-eagled on warm rocks (or on each other) to absorb the heat.

Marine iguana face
Marine iguana face
Photo © Barb & Ron Kroll

How to identify iguanas

With heads shaped like armored helmets and spines protruding from their backs and necks, marine iguanas look like creatures from sci-fi horror films.

They are actually very docile reptiles, with individual characteristics and smiles on their faces. (The exception is during the December and January breeding season when males butt heads to prevent access to their females.)

Lava lizard rests on marine iguana's head.
Lava lizard rests on marine iguana's head.
Photo © Barb & Ron Kroll

What are the differences between male and female marine iguanas? Although male iguanas are larger than females, the easiest way to identify them is by their back spines.

Female marine iguanas have low back spines and high neck spines. Male spines are about the same length on their backs and necks.

As we walked along the sand, we noticed grooves left by the tails of iguanas as they crossed the beach to warm up on lava rocks. When marine iguanas get too hot, they raise their bodies up with their front feet and let breezes cool their faces and circulate under their bodies.

Marine iguanas also raise themselves up from the ground to entice finches to groom them. We spotted a lava lizard using the head of a marine iguana as a lofty perch.

Sally Lightfoot crabs

Sally Lightfoot crab
Sally Lightfoot crab
Photo © Barb & Ron Kroll

Contrasting the primordial landscape and dragon-like reptiles are the gaudy red and orange Sally Lightfoot crabs. Their scientific name is Grapsus grapsus, but their common name refers to the way they skitter on their tiptoes across the black coastal rocks.

"Sally Lightfoot crabs are brightly colored like poisonous species to discourage birds from eating them," explained Yvonne Mortola, "but they are not poisonous."

As we walked along one of Fernandina's black sand beaches, we found a molted Sally Lightfoot crab shell, complete with translucent lightbulb-shaped orbs that covered its eyes.

Molted Sally Lightfoot crab shell
Molted Sally Lightfoot crab shell
Photo © Barb & Ron Kroll

When it is time for the crab to molt, it moves as far as possible from the water, because it is soft and vulnerable. "It hides for one week until its new shell hardens," explained Yvonne.

"Molted Sally Lightfoot crabs absorb water to increase their size, so when the shells harden they have some extra space. They sometimes eat shells to increase keratin in their new hard shells."

The marine iguanas ignored the Sally Lightfoot crabs scampering around them. Not so a curious Galapagos sea lion pup, who followed them on his flippers, as if they were wind-up toys. As for us, the crabs were just one more reason to watch our step on Fernandina Island.


TRAVEL INFORMATION

Ecoventura: www.ecoventura.com

Copa Airlines: www.copaair.com

Ecuador Ministry of Tourism: www.ecuador.travel

More things to see & do in the Galapagos Islands:

Bartolome and Pinnacle Rock Galapagos Cruise Tour

Punta Espinoza Fernandina Island Galapagos - Flightless Cormorants and Lava Cacti

Darwin Bay Tower Island Galapagos - What to See

San Cristobal Galapagos Interpretation Center, Kicker Rock and Playa Ochoa

Santa Cruz Island Galapagos - Lava Tubes and Pit Craters