Giant can be a relative term. The Giant African Land Snail is definitely a giant among land snails, even if it is only a few inches long. It also manages to be one of the world’s worst invasive species, but it is it a giant problem on St. Martin?

What’s the big deal about this giant snail? Originally from Africa, it has been spread by humans throughout much of the world’s tropics. Once it becomes established, it can transform its new home in a variety of ways, endangering local ecosystems, agriculture and even human health.

The Giant African Land Snail is hermaphroditic, so every one is able to lay eggs. They do so 100-400 eggs at a time, up to 1200 eggs per year. Once they are introduced, they are quick to take over. Getting rid of them is hard. In Florida, an infestation was eradicated in the early 1970s. The effort involved killing 18,000 snails and cost over $4 million in today’s dollars.

These snails are known to eat over 500 different kinds of plants, including many agricultural crops. They eat leaves, fruits and roots, scraping away at them with 80,000 tiny teeth on their file-like radula. They can also transmit diseases to plants, including diseases impacting cocoa, tangerines and eggplants.

In some parts of the world, these snails are also responsible for spreading certain diseases, including some caused by nematode worms that live in the snails. Luckily, humans usually catch these diseases by eating raw or undercooked Giant African Land Snails, something that most of us will have no problem avoiding.

In the Caribbean, this snail was first found in Guadeloupe in 1984. By some accounts, it arrived in St. Martin along with supplies imported when the island was rebuilding after hurricane Luis. Whether that’s true or not, Guadeloupe does seem like a likely source for our snails. Today, these snails can be found all over the island.

Since St. Martin’s major industry is tourism, this snail probably has a bigger impact on local ecology than it does on the local economy. It may harm native plants and outcompete local snails. Like many other invasive species, understanding the extent of its impact would require extensive research that has not yet been done here. On St. Martin, it may not be the giant problem it is in some places.

You can learn more about invasive species and their impact on St. Martin at Amuseum Naturalis, located at 96 Boulevard de Grand Case. The museum is free and open 4-8pm on Tuesdays and Thursdays. Get more info at http://amuseumnaturalis.com.

One of the challenges of studying the ecology of an island is uncertainty about past events. Be it twenty years, two hundred years, or two million years ago, it is impossible to go back in time to witness the first arrival of a plant or animal species. Instead, our understanding is informed by whatever historical and biological data is available.

When it comes to the Red-footed Tortoise in the Lesser Antilles, there are a few possibilities. It could have arrived on its own, floating on a raft of vegetation to each island. It could have been brought by Amerindians from South America and introduced to the islands they visited. It even could have been introduced during the colonial era or the modern era.

On St. Martin, we can probably rule out the last possibility. In 1658, Charles de Rochefort published an account of his time in the Caribbean which mentioned the presence of tortoises in the forest on St. Martin. Only settled in the 1620s, it seems likely that tortoises were living on the island before it was colonized by Europeans.

Was the Red-footed Tortoise brought to these islands by Amerindian people? Many believe this is the most likely scenario. The Arawak and Carib people migrated from northern South America—where the Red-footed Tortoise is a native species—to the Lesser Antilles. It would have been very practical to bring the tortoises with them and release them, creating a renewable food supply.

There are also reasons to believe the tortoise did not arrive on its own. Most of the reptiles that colonized the Lesser Antilles by their own means diverged into different species on each island or group of islands. The Red-footed Tortoise seems essentially the same throughout the Caribbean. This suggests it arrived recently.

Also, we know what can happen when tortoises on islands: they become giants, like the tortoises of the Seychelles and Galápagos. It would be reasonable to guess that tortoises colonizing Caribbean islands millions of years ago would have ample time to become giants.

As it turns out, we don’t need to guess that giant tortoises could exist in the Caribbean. About 40 miles from St. Martin, Sombrero Island was once home to the Sombrero Giant Tortoise. Remains of this tortoise were found in guano extracted from the island. Several other extinct species of giant tortoise are known from other parts of the Caribbean. It is possible that existing populations of giant tortoises were hunted to extinction by the earliest humans who arrived here and then replaced by the tortoises we see here today.

You can learn more about the Red-footed Tortoise and other species introduced to St. Martin at Amuseum Naturalis, located at 96 Boulevard de Grand Case. The museum is free and open 4-8pm on Tuesdays and Thursdays. Get more info at http://amuseumnaturalis.com.

Love is always in the air on steamy Caribbean nights, and you can hear the songs that prove it. A gentle hum, a sawing drone, or a piercing chirp, these calls broadcast into the darkness, pleading for partnership.

A nocturnal lifestyle has certain advantages here on St. Martin, especially if you are very small. Birds and lizards are dangerous predators to the insects and tiny frogs living on the island. One way to escape their prying eyes and hungry mouths is to hide during the day. Many of the nocturnal critters on St. Martin do just that. Johnstone’s Whistling Frog often waits out the daylight in the dampness beneath stones or under dead leaves. Many crickets and katydids hide in plain sight, camouflaged to look like the plants they live on.

Conducting all of one’s business at night does pose certain difficulties when it comes to the business of love. When predators can’t see you, neither can your prospective mate. Although there are numerous ways to find a partner in the dark, sound is one of the most common methods.

In most cases, the males do the calling. There is a fairly simple reason for this. Producing eggs requires more effort than producing sperm, so female frogs and insects are selective about who will get to fertilize them. Males are the ones that need to prove their worth, so they do the calling. The calls they make advertise both their location and their fitness.

A nighttime stroll in garden, field or forest will be filled with song. The Snowy Cricket—a tiny, delicate insect—rubs its transparent wings together to produce an airy buzz. The song from a single cricket is slight, but in a field of Bellyache Bush the chorus of hundreds can be enveloping.

The Money Bug prefers to call from tall grasses. It has a file on one forewing and and a scraper on the other. Its song is determined by the shape of these sound-making features and how it plays them. It chooses loud and grating, in a near-continuous drone broken by occasional momentary silences.

The island’s most famous nighttime singer is Johnstone’s Whistling Frog. This tiny frog fills up a huge air sac in its throat to create its trademark whistle. It is surprisingly loud, and many sleepless people have discovered how hard it is to find its source. A chorus of whistling frogs on a rainy night may be the most identifiable sound of Caribbean.

You can learn more about St. Martin’s nocturnal creatures—and listen to the sounds they make—at Amuseum Naturalis, located at 96 Boulevard de Grand Case. The museum is free and open 4-8pm on Tuesdays and Thursdays. Get more info at http://amuseumnaturalis.com.

Invasive species have a long track record of disrupting native plants and animals, particularly on islands. As Vervet Monkey populations increase, what can we expect on St. Martin?

Although they are resilient enough to survive hurricanes and droughts, island ecosystems are delicate in some ways. Invasive species, in particular, have the potential to cause destruction and disaster when they encounter islands where they have no predators and little competition. Since the year 1500, 80% of all animal extinctions have happened on islands.

St. Martin is not immune to this phenomenon. It lost three species due to the introduction of the mongoose: two lizards and one snake. Rats and mongoose are perhaps our most destructive invasive species. Both are omnivorous mammals—smart, fast and voracious. The raccoon is another, but we know less about its possible impact because it has been introduced to fewer places.

In recent years, the Vervet Monkey has been increasing its population on St. Martin. Agile and intelligent, it undoubtedly eats a wide variety of native plants and animals. Originally from Africa, this monkey was brought to St. Kitts and Barbados in the 1600s. The wild population of Vervets on St. Martin is much more recent, perhaps only a few decades old.

A look at St. Kitts may tell us a bit about one possible future on St. Martin. Monkeys are very common on the island in both the mountain forest and the dry coastal scrub. Until recently large areas of sugarcane cultivation created a buffer between mountain-dwelling monkeys and urban areas. With the end of that industry, emboldened monkeys have spread nearly throughout the island.

In the lush, beautiful forests of St. Kitts, many animals are strangely absent. Snails, so abundant on the wet slopes of Saba and even the dry forest of St. Martin are almost entirely absent. One might see a few lizards per day on Mount Liamuiga compared to a few lizards per tree on Pic Paradis. There isn’t enough research to prove that monkeys are responsible, but they are one of the few major differences between St. Kitts and other islands in the Lesser Antilles.

Once a rarely seen novelty, Vervet Monkeys are more common every year, and seem to be on the verge of becoming an island-wide menace. Will lizards found only on St. Martin be driven to extinction? Will the forest and scrub of St. Martin fill with monkeys and empty of everything else? Without action, we will find out very soon.

You can learn more about Vervet Monkeys and other invasive species on St. Martin at Amuseum Naturalis, located at 96 Boulevard de Grand Case. The museum is free and open 4-8pm on Tuesdays and Thursdays. Get more info at http://amuseumnaturalis.com.

Our salt ponds and mangrove wetlands are a complex ecosystem. Many kinds of plants and animals interact in harmony to keep St. Martin’s shores from eroding and preserve our clear waters and coral reefs. One tiny animal in particular plays a big role in holding it all together.

Fiddler crabs are small, a couple inches wide at most. On St. Martin, they are most common on the edges of our salt ponds, on sandy flats and beneath mangrove trees. Male fiddler crabs are easy to recognize because they have one enormous claw, sometimes almost as big as the rest of their body.

Why are these little crabs so important? Consider one role of our ponds and mangroves: they trap organic material and soil before it gets swept out to sea. This process counteracts erosion and also keeps the sea clean and clear, something that corals need to survive. Fiddler crabs help, bite by bite. They use their small claw to put sand in their mouth and filter out tiny bits of food from it.

Fiddler crabs also help maintain healthy mangroves by digging tunnels in the sand. The crabs dig the holes so they have a place to hide from hungry birds, but the holes also loosen and aerate the sandy ground where they live, helping the mangroves. The crabs also bring buried organic matter to the surface when tunneling, so it can be eaten. In some cases, other animals use the tunnels as hiding places, too.

Fiddler crabs are also an important source of food for many wetland animals, particularly wading birds and herons. These crabs sustain our year-round resident birds as well as migratory species that travel thousands of miles to winter here. The energy the crabs locked from filtering wet sand is provided to these birds in bite-sized packages.

It is hard to imagine what our island would be like without the fiddler crab. Our wetlands would be quite different. Familiar birds would probably be less common or gone altogether. The island could be smaller, our shorelines eroded with less protection from mangroves. Our coral reefs could be overwhelmed by algae. Rotting material trapped in the sand could even make the island smell worse. Thank goodness for our fiddler friends!

You can learn more about fiddler crabs and see them in The Crabitat at Amuseum Naturalis, located at 96 Boulevard de Grand Case. The museum is free and open 4-8pm on Tuesdays and Thursdays. Get more info at http://amuseumnaturalis.com.

The Cuban Treefrog is the only amphibian on St. Martin that needs to live in fresh water as it develops, and on St. Martin this is a very challenging proposition.

The Cuban Treefrog is native to Cuba, the Bahamas and the Cayman Islands, but humans have brought it to many other places. It now lives in Florida, Hawaii and many Caribbean islands. Although it needed the help of humans to get to new lands—probably as a stowaway with shipments of plants or other materials—it is very adept at colonizing new places once it arrives.

St. Martin poses a number of challenges for the Cuban Treefrog. For starters, there simply isn’t much fresh water. Most of the ponds on the island are salty or brackish, which is not good if you have permeable skin that can absorb salt. There are no real rivers, and most of the fresh water in guts and roadside ditches is swarming with guppies and other fish that would love to eat young tadpoles.

What’s a frog to do then? For starters, they lay a lot of eggs: 100 to 1,000 at a time. Also, they can hop to water that fish can’t reach, like livestock ponds, wells and even puddles. Of course, this means they have to grow up fast before their puddle disappears. They start by eating algae, which is the primary food for Cuban Treefrog tadpoles, but as their home gets smaller, things take a turn towards the sinister.

In the race agains time, the tadpoles will often eat their brothers and sisters. This provides the best chance for at least a few to survive and transform into frogs before their water runs out. It may seem unpleasant, but for the survival of the species, it is much better than all of the tadpoles dying when their puddle evaporates.

While their ability to thrive on a relatively dry island is impressive, it isn’t necessarily a good thing for native animals. Like all invasive species, the Cuban Treefrog can upset the delicate balance of life on an island. Animals like our native lizards—including species found only on St. Martin—are potential prey for the Cuban Treefrog.

You can learn more about both invasive species and freshwater ecosystems on St. Martin at Amuseum Naturalis, located at 96 Boulevard de Grand Case. The museum is free and open 4-8pm on Tuesdays and Thursdays. Get more info at http://amuseumnaturalis.com.

At last count, there are six different species of gecko on St. Martin. Some of them are tiny, about three centimeters long. The Tropical House Gecko is medium-sized and commonly seen climbing walls and eating insects attracted to porch lights. By comparison, the Spotted Woodslave is a monster—up to 20 centimeters overall—with a stout body and thick tail.

Many people are not familiar with the Spotted Woodslave. It is rarely seen around homes and it spends its days hiding, coming out at night to hunt. Those daytime hiding spots often include the stone slave walls that crisscross the island and crevices in the bark of old tamarind trees.

The Spotted Woodslave is instantly recognizable. It’s huge, of course, with the sturdy frame of a retired athlete. It also has a generous speckling of black spots on its tan skin. Its legs are draped in loose skin, like long underwear that is a couple sizes too big. Splits in its toe pads make its feet look cartoonishly oversized. It has enormous eyes that stick out on either side of its head like tiny planets.

It is a beautiful lizard, and one that is only found on St. Martin. St. Martiners have known this lizard since people first came to the island, but it was only described as a new species in 2011. Previously, it was considered just a variant of a sister-species, the Turnip-tailed Gecko, which is found in much of the tropical Americas.

Why does St. Martin have its own species of gecko? It’s quite hard to say, because it happened long before anyone was around to watch. Perhaps our Spotted Woodslave lived on more islands at one time, before disappearing everywhere but St. Martin. Perhaps Turnip-tailed Geckos colonized the Caribbean twice: an early group that evolved into our Spotted Woodslave, and then a more recent group that remains the same as the geckos on the mainland.

Whatever its origins, the Spotted Woodslave surely deserves wider recognition as a unique part of St. Martin’s nature. It is also part of local culture. With microscopic hooks on its toes like invisible velcro, it can climb walls. This gave rise to the myth that if a woodslave was on your skin it could only be removed by burning it with a hot iron. That myth’s not true, of course, but it is rooted in observation of this animal’s amazing climbing abilities.

You can learn more about the Spotted Woodslave and other species that are found only on St. Martin at Amuseum Naturalis. Visit the museum for free on Tuesdays and Thursdays from 4-8pm or get more info at amuseumnaturalis.com.

It is easy to love the mango tree for its sweet, juicy fruit or the flamboyant for its showy crown of flowers. Both come from far away, yet have become a part of Caribbean landscapes and cultures. The true native jewel of the Caribbean is a tree that is unfamiliar to many, but without equal in many ways.

The gaïac tree is also known as the lignum vitae, guaiacum or palo santo. It is native to the Caribbean, it is endangered and it has the hardest wood in the world. It is thought of as a small tree, but that’s not really true and it was used as a cure for many diseases, although it probably didn’t work. At one time it was one of the most important trees in the world, and it has always been one of the most beautiful.

As a native species, the gaïac evolved to live in the Caribbean. It grows slowly, but can survive in dry and inhospitable environments. They can live near salty coasts, rooted in limestone with just the slightest hint of soil. Their wood is incredibly hard, making the tree sturdy against storms and high winds.

The hardest wood in the world was also very valuable. Gaïac trees were cut down everywhere they could be found, and fashioned into a great many different objects. Mortars and pestles use to pound arrowroot were made from gaïac, as were billiard balls, police truncheons and clock gears. It was also favored for variety of ship parts, like deadeyes and shaft bearings.

In time, metals, plastics and other materials replaced gaïac wood for most uses, but by then much damage had been done to this tree. The thousand-year-old trees reaching nearly 20 meters into the sky are almost entirely gone now. The hundred-year-old trees that have grown up since then lead us to believe that the gaïac is a small species.

It remains incredibly beautiful, with a thick canopy that changes color with the seasons. Deep green leaves stand out during the dry season when the tree is surrounded by browns and yellows. Blue flowers explode into bloom once or twice a year, creating a flurry of activity by bees and butterflies. Tens of thousands of orange fruit can cover a mature tree, bursting open to reveal the seeds in their bright red coating.

Today the gaïac is resurgent on St. Martin, planted in yards and along roadsides by those familiar with its charms. In a century or two, perhaps it will reclaim its rightful place on the island and in the imagination of those living here. Learn more about the gaïac at Amuseum Naturalis. Visit the museum for free on Tuesdays and Thursdays from 4-8pm or get more info at amuseumnaturalis.com.

Caribbean Curiosities is a brand new column in The Daily Herald’s Weekender section. Each week, the column will take a closer look at something from the strange and wonderful world of St. Martin’s nature. Everything featured in Caribbean Curiosities can also be found at Amuseum Naturalis.