A celebration of wrinkles!! The esthetics of the Wrinkle-faced Bat

It is safe to say that Tracie and I love bats. Fortunately for us Costa Rica has massive diversity when it comes to these flying mammals. Scientists have identified around 240 mammals in Costa Rica of which 113 are bats. The Osa Peninsula has the highest bat diversity in the country with 80 identified species.

Even so, bats can be elusive during the Night Tour. Most of our sightings are fleeting views of bats flying by at breakneck speed. At times we are also approached by insectivorous bats capitalizing on the insects attracted by our headlamps.

Occasionally we are fortunate enough to encounter roosting bats which we can observe in detail. These prized encounters, although usually brief, are always memorable. By far the most memorable bat encounter we have had is with the Wrinkle-faced Bat, Centurio senex. Wrinkle-faced Bat - Centurio senex

This bat is so different from other bats it is the only member of its genus: Centurio. The binomial name is derived from the Latin words centurio, meaning 100, and senex, meaning old or aged, because its face looks like that of a 100 year old person.

It is not known why these bats evolved such a wrinkly face, but it is though that perhaps the wrinkles act as canals to channel juices into the bat’s mouth as it feeds on ripe fruit.

Male bat’s faces are wrinklier than the females’ faces and they also have chin folds which they stretch over their faces while roosting. A swollen ridge along the bat’s foreheads prevents the face mask from slipping and, incredibly, the masks are complete with transparent “window panes” over the area covering the eyes!!

Wrinkle-faced Bats have a very short and wide skull which allows them to apply about 20% more force in their bite compared to other similarly sized bats. Scientists believe that this allows Wrinkle-faced Bats to feed on harder fruits than other frugivorous bats. They also have pouches in their mouth where they can store spare fruit.

Wrinkle-faced Bat - Centurio senex

Wrinkle-faced Bat feeding on fruit. Notice its massive thumbs!!! Click on the photo for a larger image

Another impressive feature about these bats are their massive thumbs. It seems this is an obvious adaptation which allows the bat to grip and feed on large fruit, although their feeding habits are poorly understood. Very little is actually known about these handsome bats. Roosts are rarely found and scientists think they may roost high in the canopy.

The facial features of the Wrinkle-faced Bat make it one of the most unusual mammals in Costa Rica. Some may say they have a face only a mother could love. To us, though, their unique looks represent the beauty and diversity awaiting discovery in the tropical rainforest.
Wrinkle-faced Bat - Centurio senex

LaVal, R. & Rodríguez, B. 2002 Murciélagos de Costa Rica / Bats Editorial INBio
Wainwright, M. 2002 The Natural History of Costa Rican Mammals Zona Tropical

The Mysterious Velvet Worm

Velvet Worms are small, elusive and secretive creatures. Because of their size and

Velvet Worm photographed in Drake Bay, Costa Rica on the Night Tour © Gianfranco Gómez

Velvet Worm photographed in Drake Bay, Costa Rica on the Night Tour © Gianfranco Gómez

semi-fossorial lifestyle they are not easy to find.

Guests on the tour are sometimes a bit puzzled as to why this strange little worm-like animal should cause their guides so much excitement, but a glimpse into the life history of Velvet Worms reveals a creature nothing short of phenomenal.

The first line of the scholarly paper: “A new giant species of placented worm and the mechanism by which onychophorans weave their nets (Onychophora: Peripatidae)” by Bernal Morera Brenes and Julián Monge Nájera puts it all into perspective by stating:

Onychophorans, or velvet worms, are small 
invertebrates that most biologists study in theory, but due to their rarity, 
never see in the real life“.

Encounters with these enigmatic creatures are always special because of their rarity and because of these organisms’ ancient legacy.

The origin of Velvet Worms is still not well understood. One thing that is not in contention, though, is that these little creatures are living fossils. Due to the soft structure of their bodies, Velvet Worm fossils don’t preserve very well. Even so, fossils have been found dating as far back as 500 million years ago when Velvet Worms were marine

By Gunnar Ries Amphibol (Own work (own photo)) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

animals. The fossilized creature pictured right, which was discovered in Cambrian Burgess Shale, looks remarkably similar to the Velvet Worms that roam the earth today. They are thought to have crawled out of the ocean about 430 million years ago where they evolved in the inter-tidal zone until eventually colonizing land.

One of the things that make Velvet Worms so special is simply how different they are from any other animal on the planet. In fact, they are so different that they are grouped in their own Phylum: Onychophora. Mammals, for example, belong to the Phylum Chordata. It is made up of about 60,000 incredibly diverse species including sea squirts, fish, birds, amphibians, and reptiles. Taking this into consideration, it is remarkable to think that Velvet Worms have been placed into a Phylum of their own containing less than 200 species. Onychophora is divided into two families: Peripatidae and Peripatopsidae. Only Peripatidae is represented in Costa Rica.

Velvet Worm photographed in Drake Bay, Costa Rica on the Night Tour © Gianfranco Gómez

Velvet Worm photographed in Drake Bay, Costa Rica on the Night Tour © Gianfranco Gómez

The word Onychophora is derived from the Greek words onyx, meaning nail or claw, and phoros, meaning to carry or to bear. They are given the name “claw-bearers” because Velvet Worms are equipped with a pair of claws on each one of their feet. Velvet Worms found in Costa Rica usually have between 22 and 43 pairs of legs. Their skin is covered with very fine “papillae”, or tissue projections, which are covered by tiny scales. These papillae give Velvet Worms their “velvety” appearance and account for their common name.

Perhaps Velvet Worms’ most remarkable feature is a pair of slime glands present on either side of the head. This feature is unique to Velvet Worms and represents their foremost weapon for hunting prey.  While hunting, Velvet Worms use their antennae and chemosensory organs near their mouth to identify prey.  

Once they decide to attack, Velvet Worms shoot white, sticky slime from glands located below their antennae. Velvet Worms have the astounding ability to shoot their slime at a rate of 5 meters per second!! This is a world record in the animal kingdom, as there is no other animal capable of propelling anything at a faster rate. As the slime ensnares their prey, the Velvet Worms pounce and inject digestive saliva before starting to consume it. The slime is also re-ingested in order to recycle valuable protein.

Velvet Worm giving birth. Photograph taken in Drake Bay, Costa Rica on the Night Tour © Gianfranco Gómez

Velvet Worm giving birth. Photograph taken in Drake Bay, Costa Rica on the Night Tour © Gianfranco Gómez

The many reproductive cycles known to occur among Velvet Worms are also fascinating. One species of Velvet Worm  reproduces by parthenogenesis and no  males of that species have ever been discovered.

Some species, all of which are found outside of Costa Rica, reproduce by laying eggs. Most Velvet Worms are “ovoviviparous”, meaning that they develop as eggs in the mother’s uterus and hatch from the eggs only a short time before birth.

Finally, some Velvet Worms are live-bearing and the young develop as embryos in the mother’s uterus. They are nourished via secretions released from the mother’s uterus or via a placenta. These are the only placental invertebrates on the planet. The diversity of reproductive cycles occurring within Velvet Worms is astounding, especially considering there are less than 200 species.

A few nights ago, on March 13, 2013, we had what was by far our most amazing Velvet Worm encounter. We were walking back to Jinetes de Osa

Velvet Worm giving birth. Photograph taken in Drake Bay, Costa Rica on the Night Tour © Gianfranco Gómez

Velvet Worm giving birth. Photograph taken in Drake Bay, Costa Rica on the Night Tour © Gianfranco Gómez

towards the end of a Night Tour. We stopped to look at a Burrowing Tarantula when I noticed a Velvet Worm not far from the Tarantula’s burrow. As I leaned in to get a closer look, I saw what I thought to be the Velvet Worm feeding on something. I had a closer look, trying to identify the prey item, but something seemed to be off. Suddenly I realized, to my disbelief, that I was

looking at the Velvet Worm’s rear end and it was actually giving birth! Blown away by what we were witnessing, I took out my camera and started clicking shots off. We watched in awe as the tiny little baby Velvet Worm was born and I stayed behind to capture the newborn’s first few minutes on earth.

The newborn Velvet Worm crawled cautiously, exploring this brand new world but never straying too far from its mother. The mother, seemingly exhausted by the birth process, stood motionless as its newborn examined the surrounding area. Amazing! For us to have witnessed this ancient creature bringing this tiny being into our modern world was truly a privilege.

Velvet Worm with newborn offspring, minutes after birth. Photograph taken in Drake Bay, Costa Rica on the Night Tour © Gianfranco Gómez

Velvet Worm with newborn offspring, minutes after birth. Photograph taken in Drake Bay, Costa Rica on the Night Tour © Gianfranco Gómez

After several minutes we left the two little Velvet Worms and headed home. We walked back silently, still reeling from what we had seen. Lost in thought, I could not help wondering how this small, delicate, soft bodied creature had outlived so many others during the last 500 million years.

How could this tiny creature have managed to survive so many mass extinctions, natural disasters, ice ages, the shifting of the continents, to outlive the dinosaurs and so many other creatures and still be with us today?  I suppose the only answer is that Velvet Worms, small and fragile as they might seem, are perfectly adapted for the environment they live in. As long as they have undergrowth and leaf litter to inhabit, they may well survive the current mass extinction brought on by humans and outlast us all.

We are currently working with researchers at the Universidad Nacional de Costa Rica on identifying a couple of new species of Velvet Worms from Drake Bay as well as studying their ecology and behavior.

posted by Gianfranco

In the Presence of the Jaguar

There is no question that the most elusive, imposing and impressive mammal in Costa Rica’s rainforests is the Jaguar, Panthera onca.  The word itself, Jaguar, is derived from the Guaraní Indian word yaguara meaning “he who kills with one bound”.  Native Americans throughout their range have venerated these apex predators for their power, stealth and beauty.  In many cultures they are treated as god-like entities and their presence has been woven into many mythologies.  Their likeness graces the walls of many temples, carvings, paintings, and ceremonial masks all over America.

Indigenous Vessel with Jaguar Image Discovered in Nicoya, Costa Rica
Image Sourced from the Wikimedia Foundation – www.commons.wikimedia.org

It is easy to see why these animals are so revered.  Jaguars are the third largest cats in the world, behind the Lion and the Tiger, and they are the largest cats in the Western Hemisphere.  To the native people that share its range, the Jaguar is the ultimate hunter.  It symbolizes fear, respect and reverence.

Jaguars are now extremely endangered throughout their once great territory and have been completely wiped out in many areas where they once thrived.  Encounters with these magnificent beasts are rare and often fleeting.   Though I had been intrigued by these cats for most of my life, I had never been close to a Jaguar until my late twenties.

It was then, while working as a canopy tour guide in Rincón de la Vieja, that I first began to understand their power.  One night, a Jaguar attacked and killed a cow on the farm where I worked. At the time, the farm was in a legal dispute and the police were called in to inspect the kill.  They needed to do so in order to make sure it had not been illegally slaughtered for food by the people in possession of the land.  When the police showed up the next day and were taken to the kill site, to everyone’s surprise the Jaguar had returned overnight and dragged the carcass 50 meters to the base of a tree, where it had been feeding on its prize!  This is an awesome display of power, considering that the average cow can be up to three times as heavy as the average Jaguar.  Jaguars have been known to take down bulls weighing up to 800 pounds and are considered a pest by cattle ranchers throughout Latin America.  It was hard to imagine such a powerful creature lurking in the forest, living among us.

Jaguar – Panthera onca
By USFWS [Public domain], via Wikimedia Commons

A couple of years later, in 2001, I was hiking with a friend from Carate to Sirena Station, in Corcovado National Park.  It was here that I had my first face to face encounter with a Jaguar. We left Carate very early in the morning and embarked on the 20 km hike to Sirena Station.  The hike was amazing, with an abundance of wildlife.  Gigantic, scattered whale bones littered one beach giving this primeval place a prehistoric aura.  It felt as though we had stepped back in time.  About half way through our trip we arrived at a long beach called Playa Chancha.  As we rounded the rocky outcrop at the beginning of the beach, we stopped to rest, get a drink of water, and soak in the raw beauty of Corcovado National Park.  We were sipping our water bottles, when my friend said “What the hell is that!”  I turned to look behind me and saw a large, black figure walking down the beach, towards us, about 500 meters away.  We watched it for a while when, suddenly, it turned.  We got a full, profile view of an adult, all-black, or melanistic, Jaguar.  After a few seconds the cat literally took two leaps and disappeared into the forest.  Stunned by what we had seen, we walked down the beach until we came across these massive paw prints sunk deep in the sand. They were twice as wide as my size 41 feet (about 8.5) and about half as long. Impressive!

Jaguars often patrol the beaches of Corcovado and Tortuguero National Parks in search of sea turtles.  As unsuspecting sea turtles arrive on the beach to lay their eggs, marauding Jaguars pounce and turn them into an easy meal.  Their bite is the strongest of all the world’s wild cats – almost twice as strong as the Lion, and the second strongest of all mammals, after the Spotted Hyena.  They can pulverize even the sturdiest of bones and can perforate a turtle’s shell as easily as we would bite through a banana.  Elated by our encounter, we continued on to Sirena Station where we spent the next two nights.  The remainder of our trip was overshadowed by the 15 or 20 seconds we spent in the presence of the Jaguar on Playa Chancha.

Corcovado National Park – Sirena River Mouth

Six years later, I was to meet this elusive cat again.  Tracie and I were walking back home from Drake Bay Wilderness Resort after a tour.  My eyes were killing me because, although I didn’t know it at the time, I had sustained a scratched cornea that night that would take me on an emergency flight to San José the next day for treatment.  As we headed up the hill towards La Paloma Lodge I looked up and there was this massive black Jaguar about 10 feet in front of us, right in the middle of the trail!  Before I could say anything, the cat took two leaps and was gone.  The most amazing thing about this encounter was how, despite its size, this animal moved in complete silence.  We were not very far from it when it leapt into the forest.

Melanistic Jaguar – Panthera onca

We looked for it for some time afterwards, but there was no sign of the cat.  We didn’t hear even the slightest sound – not a leaf crinkling, not a twig breaking, just absolute silence.  It was as if we had imagined the whole thing – or had just seen a ghost.   Thick pads on the bottom of their feet allow Jaguars to move silently through the forest.  They move so silently, that people often don’t realize a Jaguar is nearby until they see their tracks.  As I sat on the plane with my aching eyes closed the next day, my thoughts were haunted by this silent predator.  Was it flesh and bone or was it some ghostly jungle spirit we had seen that night?

Last Saturday night, November 24th, 2012 we were out on The Night Tour with guests from Finca Maresia and La Paloma Lodge.  It was an amazing night filled with great encounters. We saw a Leaf Katydid (Mimetica sp.), an incredible brown and green morph that we had only seen one other time before, about ten years ago.  Other highlights included a Gaudy Leaf Frog, a Giant Walking Stick, an incredibly rare Ray Spider, an Emerald Glass Frog and an Eyelash Pit-viper. Towards the end of the evening we also encountered a pair of Granular Glass Frogs (Cochranella granulosa) in auxiliary amplexus.  They were on a tree next to the hanging bridge that spans the Agujitas River.  Since Tracie and I had never seen these tiny frogs in their breeding position before, we decided to stop back after the tour to get some photographs.

Granular Glass Frogs in Axillary Amplexus – Note the eggs clearly visible in the female’s abdomen
Cochranella granulosa

We managed to locate the frogs and even though they were on a leaf about ten feet from the bridge, and their maximum size is about 31 millimeters (about 1 ¼ inches), I managed to get some shots with a telephoto lens as Tracie lit the frogs up with her handheld flashlight.

After a while Tracie said: “Maybe, if we turn off our lights, they will start laying their eggs.”  We waited in complete darkness.  By now it was nearing midnight.  After some 15 minutes with our lights off we suddenly heard a low, guttural growl coming from the river’s edge, about 6 feet from the bridge.  We stood silently, not quite knowing what to make of this menacing sound, when we heard it again! (Click here to listen to the Jaguar’s Growl: Jaguar Growl ) A rock then rolled down the bank and fell into the river making a small splash. I turned to Tracie and said: “There’s an animal down there!” and we simultaneously turned on our headlamps.  As the light pierced through the darkness, it lit up a shadowy figure standing on the river’s edge.  The Jaguar’s identity was revealed by the incredibly intense, bright golden glow of the animal’s eyeshine.  It, too, was an all black cat.  We looked at each other for a second and then it disappeared.  We ran about five feet to the trail and managed to catch a glimpse of the Jaguar’s tail and rear end, about 20 feet away at this point, as it was swallowed up silently by the dark forest.  Though it was a shocking sight for us indeed, it is not so surprising to find a Jaguar at a river’s edge.

By Bruce McAdam from Reykjavik, Iceland (Panther Uploaded by BruceMcAdam) [CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons

Jaguars are quite aquatic and regularly hunt in or around rivers.  They have been observed fishing, by tapping their paws on the water and luring fish to the surface.  They are also known to wrestle and eat Cayman and small Crocodiles!

After a few minutes of frantically searching the forest, yearning for another glimpse, we gave up our search and started walking home.  As we looked back on what had just happened and assimilated our time in the presence of the Jaguar we couldn’t help feeling blessed to live in a place where an encounter like this is still possible. The thought of sharing a moment of space and time with such an amazing creature, to hear its growl and meet its gaze as we crossed paths in the forest gave us an uplifting thrill – a thrill hard to match, except while staring into the mysterious eyes of the jungle’s top predator.

Posted by Gianfranco and Tracie

The Snake of Many Colors

Eyelash Pit-viper photographed in Drake Bay, Costa Rica

One of the most beautiful and impressive snakes in Costa Rica is the Eyelash Pit-viper, Bothriechis schlegelii. Like most other Costa Rican Pit-vipers, Eyelash Pit-vipers give live birth. They have countless color variations, and many morphs have been documented and can be observed even in the same litter! In Drake Bay all of the Eyelash Pit-vipers we have encountered have had some variation of the mottled, green morph shown on the photograph above.

Eyelash Pit-viper photographed in Corcovado National Park, Sirena Station

These small, arboreal snakes are found throughout Costa Rica’s lowland rainforests. Their common name is derived from the specialized scales located above their eyes. These curiously shaped scales curve upward, resembling eyelashes. The scales’ function is still unknown, although some scientists theorize the scales may provide eye protection to the snakes as they make their way through the thick, often tangled arboreal vegetation which they inhabit.

Eyelash Pit-vipers have a small, prehensile tail which also greatly enhances their arboreal

Eyelash Pit-viper photographed in Drake Bay, Costa Rica

lifestyle. These sedate snakes are sit-and-wait predators and may spend several days on a perch waiting for their prey to blunder by. When this happens, the lethargic viper springs into action with blinding speed and delivers its deadly bite.

Once they have their prey, Eyelash Pit-vipers will hold on to it until it has succumbed to their venom. The venom not only kills its prey, but immediately begins digesting it, even before it is eaten. This allows Pit-vipers to take larger prey than non-venomous snakes. Prey items may include: lizards, frogs, bats and birds. Some scientists think that Eyelash Pit-vipers, especially the golden morph, may intentionally perch on flowers with the intention of ambushing unsuspecting hummingbirds as they come in to feed. Hummingbirds are very attracted to red and yellow….in this case a fatal attraction.

In Drake Bay we don’t tend to see these amazing creatures as often as we do other snakes. By far, our most common Pit-viper here is the Fer-de-lance, Bothrops asper. The last two nights we have been fortunate enough to have encountered a large (approximately 50 cm long) and incredibly beautiful Eyelash Pit-viper during the Night Tour. The snake’s photograph is included at the top of this post.

Eyelash Pit-viper photographed in Drake Bay, Costa Rica

Posted by Gianfranco

The Bluntheaded Snake: the ultimate lizard predator

One of the most strikingly specialized reptiles making its home in Drake Bay’s rainforest is

Bluntheaded Snake – Imantodes cenchoa

the Common Bluntheaded Snake, Imantodes cenchoa. These common nocturnal snakes are unlikely to be confused with any other snake in the area besides their close relatives: the rarely seen Banded Bluntheaded Snake (Imantodes gemnistratus) and the equally rare Speckled Bluntheaded Snake (Imantodes inornatus). Their slender, streamlined body sets these snakes apart from most other snakes and is crucial in capturing their favorite meals: sleeping lizards.

Bluntheaded SnakeIn Costa Rica, most lizards are diurnal and usually sleep through the night. Due to the countless threats faced by these creatures once darkness shrouds the forest, lizards have developed an ingenious survival strategy.

When choosing a perch to pass the night, most lizards wisely seek out the mid-line of a leaf or a very delicate branch or vine. This way, if they feel the movement of something moving up the plant to eat them sometime during the night, they can simply drop to the ground and make a quick escape from danger. Generally, this is a really good strategy, but the Bluntheaded Snake’s highly specialized skeletal structure helps them surpass it.

The Bluntheaded Snake’s skeletal structure is not unlike the structure of an I-beam. In cross section, the snake’s body is more reminiscent of a triangle than the more common tubular shape of most other snakes. This, along with interlocking vertebrae and reinforcing back scales, allows Bluntheaded Snakes to stretch more than half of their body into mid-air and snatch the unsuspecting lizards from their perch without ever touching the plant. A very long, prehensile, tail has the strength to support all of the Bluntheaded Snake’s body weight, giving them an extra advantage when hunting from above. Also, the snake has massive

Bluntheaded Snake feeding on an Anole Lizard

eyes which it can actually cast downward, providing Bluntheaded Snakes an effortless, inconspicuous view from above. All things considered, the poor lizards have little chance against such a formidable predator. The moral of the story: in the rainforest every good strategy has an even better counter-strategy.

Bluntheaded Snakes are rear-fanged snakes which are used to inject a mild venom. Once

they have secured their prey, their venom will immobilize it before they begin feeding. They can take prey up to ten times the size of their very narrow neck and adult snakes can easily feed on juvenile Green Iguanas and Basilisks. Despite being mildly venomous, Bluntheaded Snakes are docile and gentle creatures.

They do not bite as a defensive reaction and are easily handled. An encounter with a Bluntheaded Snake is always very special indeed. It gives our guests on the Night Tour the chance to handle these magnificent creatures, dispelling the ingrained fear of snakes held by many and replacing it with admiration and respect for a creature that has evolved to dominate its niche.

Posted by Gianfranco

Costa Rica’s Green Ambassador

Gaudy Leaf Frog - Agalychnis callidryas

Gaudy Leaf Frog photographed on the Night Tour

The Gaudy Leaf Frog, Agalychnis callidryas, has come to be one of the best known ambassadors for Costa Rica. Along with toucans, monkeys and quetzals, Gaudy Leaf Frogs have come to embody all the enchantment and beauty awaiting discovery in the tropical rainforest. In Drake Bay, we are lucky enough to have these lovely creatures as a mainstay on The Night Tour. Their charm and style never fail to marvel guests and guides alike, and usually make for one of our most popular encounters.

Gaudy Leaf Frogs are more active during the rainy season, when they breed,  and are much easier to find.  Males tend to call from their perches in the hope of attracting a gravid female with which to mate.  An anxious female may sit for hours listening to these calling males before choosing the one she is attracted to.  At this point she will walk towards her chosen mate pretty much in a straight line.

Gaudy Leaf Frogs in axillary amplexus

Gaudy Leaf Frogs in axillary amplexus

Once they meet, they will  embrace in axillary ampexus and begin the mating process. The female frog begins her search for a suitable leaf        on which to lay her eggs. She may lay between 10 and 100 eggs in a single egg clutch; and may lay up to 5 egg clutches in one night for a maximum total of 265 eggs. The eggs are transparent.  As such, the developing tadpoles can be observed wiggling around, as they grow larger and larger during the course of a week.

After 7 days of development, hatching usually occurs during a heavy rain. The tadpoles scramble out of the egg

Gaudy Leaf Frog Eggs

Gaudy Leaf Frog Eggs

mass, which has provided them with nourishment and protection. Once they are free of the egg mass, the tadpoles fall to the ground and are swept away by the torrent of heavy rain. Hopefully they will end up in a puddle, where they will finish their development and eventually transform into tiny little frogs.

When they do emerge from their puddle as newly formed frogs, Gaudy Leaf Frogs look very different from their emblematic adult form. We have actually raised these amazing creatures at

Gaudy Leaf Frog Juvenile

Gaudy Leaf Frog Juvenile

home, in an aquarium, from their eggs stage until they emerged from the water. With a steady diet of flake fish food they completed their metamorphosis in about a month with minimal casualties. In nature this process may take as long as 80 days and the survival rate is low. The photograph above was taken the day this lovely little Gaudy Leaf Frog left the water, as it was being released back into the wild.

– Posted by Gianfranco