Crocodiles in the mangroves

With the excitement of our adventure at Villa Blanca still bubbling within us, we set forth the next day to Puntarenas for our first tropical marine biology field trip; a visit to the mangroves.

Mangroves are fascinating even from a distance. They're the murky, dense forest you might picture when you invision swamps filled with alligators and creepy things like gill-man from the movie Creature from the  Black Lagoon. The water is a chocolate brown, and the smell is salty and a little pungent. 

Mangroves are a kind of tree that survive where no other trees can, where fresh water rivers meet a salty ocean. Not only do the trees that exists here have to deal with excess salt in the water, but they also must deal with the rising and lowering of the tides. 

There are a few animals who do well in this interesting ecosystem, from small crabs to 8ft long American crocodiles, Osprey, Spoonbills, and more. 

On the boat ride in we saw this Spoonbill in a tree. It was hard to get a good picture of it, but they have an odd, spoon shaped bill used for searching for prey in the murky waters.

Osprey

This was the trip that I started to get a reputation for myself as being someone who is good at finding cool things. I had noticed an iguana running along the shore and pointed it out. Another girl said "Nice find Jen! Now find me a crocodile!"

And I just happened to glance at the shoreline..and what do you know....

The class couldn't believe it, and kept telling me to find neat things. Unfortunately, I only located the American crocodile that day.

We hopped off the boat once we reached the mangroves, and noticed that the mud gave off a terrible smell when disturbed. The soil has a lack of oxygen, and this lack of oxygen produces a rather strong rotten egg smell.

We muddled through the mud however, to watch crabs climb the trees, and strange shrimp swim in the water near the shore. A few of us nearly got stuck in the mud.

Muddy boats

There are three different types of mangroves, and they vary depending on their salt water tolerance. The most tolerant of salt water is the Black mangrove, which has roots that trick up out of the ground like tooth brush bristles. These are called pneumataphores and are used to trap oxygen from the air, since the soil is oxygen deprived. 

Black mangrove tree seedlings actually germinate and stay attached to the parent tree until it becomes heavy enough so that it won't drift with the tide into the open ocean, where it would never survive. 

Black Mangrove Forest

Red mangroves are less tolerant of salt water, so they are further up the river than the Black mangrove trees. These are the trees with the easily recognizable prop root system, that makes the tree look as though it's walking. The roots are covered with a waxy layer to keep salt out, and the trees dispose of salt that gets in by sending it to older leaves which are shed. 

The last type of mangrove, which we did not see, is the White mangrove. This is the most sensitive to salt, and the shortest of the mangrove trees. 

Red Mangrove forest. Notice the strange areal roots that distinguishes it from the Black Mangrove trees.

On the return boat ride we got a lucky surprise, the bank where I had seen the iguana run past before was covered in basking crocodiles!!!

Despite their awesome size and power, crocodiles are shy of humans, and they retreated off the bank as we got closer. 

Here, if you look closely, you can see a pair of eyes watching us in the water

We then stopped at a small beach for a swim, and went on a short hike. If we had time to make it to the end of the hike, we would have made it to an old jail that had been very corrupt and had closed only 20 years ago. There were rumors that prisoners had tried to escape the island by swimming away in the ocean, but many didn't make it as there are a lot of sharks in that part of the ocean.

I'm not sure how much of that rumor is true, as sharks don't attack people the way the news or Hollywood would have you believe. But it's a spooky thought nevertheless.

After another boat ride home, it was time to pack for school and another week of studying in Costa Rica.

Pelicans.