Wildlife champion

Why Monty Halls admires marine iguanas

Why have you chosen the marine iguana?

Though it’s an iconic animal, beloved of every tourist who visits the Galápagos, it’s also rather misunderstood. When Charles Darwin first saw marine iguanas in 1835, he described them as “disgusting, clumsy lizards” and “imps of darkness”. But we now know they are great survivors, miracles of evolutionary adaptation and truly unique reptiles.

What makes them unique?

Endemic to the Galápagos Islands, marine iguanas are the only lizards on Earth dependant on a diet of algae, and therefore adapted to forage at sea. The species has a few tricks to help it cope with what can be a challenging environment, but perhaps the most impressive is its ability to shrink its skeleton by up to 20 per cent when algae is dramatically reduced by El Niño. It’s a bit like me becoming as short as comedian Ronnie Corbett when food is sparse. To radically decrease your body size, and therefore your energy demands, is a perfect survival tool.

What’s been your most memorable encounter?

While staying in the Galápagos in 2000,

I came across a marine iguana lying in front of the door of my shoreside hut. I didn’t know what to do with the large ‘draft excluder’. In the end, I eased it aside with a f lip-flop and received a good blast of salt for my troubles. Marine iguanas expel excess salt from glands near their noses by sneezing. To me, it also seems to be their way of expressing displeasure if a human gets too close: I’ve discovered this response works well at a dinner party.

Why are they important to the ecosystem?

The archipelago actually has relatively low species diversity – every animal is precious in this delicately balanced island environment. By grazing on marine algae, the iguanas prevent it from smothering the reefs. They also transport nutrients from sea to land when they excrete.

Do they face any threats?

Climate change may radically affect their diet, and as an animal that essentially eats one type of algae – which is sensitive to water temperature – that’s a real issue. Increasing tourism, pollution (the most recent oil spill in the Galápagos occurred off San Cristóbal Island in December 2019), loss of habitat and predation by introduced predators such as cats, dogs and rats, also take their toll.

How is the archipelago being protected?

Much of the work of the Galapagos Conservation Trust involves rewilding, the eradication of invasive animals and reintroduction of endemic and native species. The Galápagos Islands have seen some of the worst environmental excesses of man, but they also offer a chance to show that we can right these wrongs. Get it right here, and the same model can be rolled out in other island groups.

S I eased it aside with a flip-flop and received a good blast of salt for my troubles. T