MARINE TOAD: BEAUTY OR THE BEAST

 

Marine Toad: Beauty or the Beast

The sun had set some hours ago and now everyone was gathering in the dining room for the evening meal.  It had been a tiring day.  There were those who had walked the trails,  trekking along paths through the forest, battling against the oppressive heat and humidity in search of exotic neotropical wildlife.  Others had taken on the task of walking down to the beaches to soak up the sun and play in the surf.  Wherever the adventure had taken them, one thing they now had in common was that they had stoked up an appetite.  Everyone was famished.  The buffet table was laid out.   There was a range of dishes, each one complementing the other and all looking delicious.  Everyone filled a plate, sat down and the meal began.

Female Marine Toad, (Rhinella marina)

Unbeknownst to the diners, they were being watched.  Gazing out at the scene from nooks and crannies all around the restaurant were eyes, not human eyes but rather those of another creature waiting for one feast to end and for another to begin.  They would not emerge while the lights were ablaze, but those lights are important for what would happen later.  While the diners ate, talked and laughed their way through the evening they were unaware of something happening around them.

From the depths of darkness in the surrounding forest, insects were being attracted, like the proverbial moth to a flame, towards the bright and beckoning lights illuminating the restaurant.  Once there, they would settle.  Normally using the light from celestial bodies to navigate, these flying insects had unwittingly been drawn to an artificial source of light and having arrived there were fooled by its brightness into thinking it was day.  So there they stopped.  The eyes were still watching though and the watcher was waiting.

Presently the meal and following conversations ended.  Sated and ready for bed, the guests proceeded to leave for their cabins, while the waiters cleared the tables.  The time was getting closer.  Eventually with the floor swept, the dishes washed and the tables set for the following day’s breakfast, the staff left the building.  The final action was to turn off all the lights.  Now something stirred, eyes blinked, patiently waiting for the security that no human had been left behind.

After a few minutes of silence and total darkness, movement could be detected.  A small squat creature squeezes from behind books in the library and comes hopping across the floor.  From under the low levels of the shelves, from the surrounding flower borders more of the creatures emerge.  They now gather in the empty restaurant and tonight’s second sitting begins.  The new diners have dry, warty skins and hop across the tiled floor to the areas of the recently turned off lights.  These are Marine Toads, (Rhinella marina), and they have come to eat the insects that were attracted to the lights over the course of the early evening.

The name Marine Toad is derived from the fact that you can find them down on the beach but they are not tolerant of salt water so you won’t find them in the sea.  They are not generally found in the forest but rather around human habitation.  Also, they do not always need the stimulus of movement to feed, as do most amphibians, so they can take food from pet bowls that have been left overnight.  Males will grow to about a year old, females will continue to grow to about four years old.  At four years, the female Marine Toad can be anything up to 3 lbs in weight, making this the largest of the Costa Rican amphibians.

They are very poisonous; the two main poison sacs, the parotid glands, appear as large expanded areas , one behind each eye.  These are the toads that were introduced into Australia in the 1930’s to clear the cane beetles from the cane fields.  The Australian predators had never come across them before, fed on them, were poisoned and died.  That left Australia with a much bigger problem than it had originally, a massive explosion in the mouse and rat populations.  They have been introduced to Hawaii, Florida, Australia, Papua, and some Caribbean Islands, all resulting in the same problems, not the fault of the toad as it is humans that take them there.

No-one in Australia thought to talk to a biologist about that biological control technique, as the cane beetles they were introduced to feed upon live at the top of the cane stems whereas the toads live at the bottom.  From that time to this, despite the Australian government introducing measures to reduce the populations of Marine Toads, it has continued to be an ecological disaster of  the countries own making.

Marine Toads return to the water to reproduce and each female can lay upto 13,000 eggs.  That many eggs with no predators means the Marine Toads can get out of control very quickly.  In Costa Rica the Marine Toad is native, it does have predators.  Opossums will catch them, split them open and leave the skins while some snakes are immune to the toxin.  Not too many will initially take a look at a toad and appreciate its beauty, but just before you vent you disgust have one more look deep into that eye, perhaps then you will see something different.

Marine Toad, (Rhinella marina). Close up.

There have been recorded instances of people trying to make a meal of this toxic amphibian, the consequences of which ended with dire results.  The following passage describes the ill-fated attempt by a family to cook and eat this particular amphibian.

“About 10 a.m. all four members of the family began to vomit……The mother and sister were prostrate, and their lips and fingers were blue; pustules had formed on the sister’s lips.  The abdomens of the mother and the sister appeared bloated and their bodies were hot and quite rigid.  They were pronounced dead by 12 noon…..The Peruvian intern in charge believed death was due to ‘cardiac seizure”, preceded by respiratory difficulties”.

The milky white toxin secreted from pores in the skin is Bufotoxin which causes massive vaso-dilation and poisoning of the cardiac muscle tissue.  So Marine Toad pie is off the menu.

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