11. Edge Effect

This is stop #11. 


The edge effect in ecology refers to a situation where one habitat type meets another.  The edge effect increases biodiversity within an area.


At this spot, you can see the influence of several habitats: the mangrove forest, fresh water pond, uplands areas, and the manmade structure of the road.  


Looking across the road, you can see the mangrove swamp associated with the Indian River Lagoon and all three species of mangrove.


Looking towards the pond, you can see leatherleaf ferns – typically associated with

Freshwater wetlands.


Finally, looking further down the trail you can see a slight rise in elevation.  These are small uplands areas.  Here, you find strangler figs, cabbage palms, morning glory, and live oak.


Near the foot bridge, you might be able to find some large holes in the ground.  The holes are about 3 inches in diameter – or bigger!  These are the burrows of the giant land crab. 


The giant land crab is the largest of Florida's semi-terrestrial crabs. This animal can measure up to 6 inches across its carapace (top shell). As a juvenile, the crab is purple or orange. As an adult, it is bluish-gray. Females sometimes appear light gray or white.  One claw is larger than the other and the walking legs are sparsely hairy.


They live in burrows at a level that will allow water to seep in for moisture. Giant land crabs are primarily herbivores, preferring tender leaves, fruits, berries, and flowers. Occasionally they will eat beetles or other large insects.


After mating, an adult female carries the egg mass beneath her body for approximately 2 weeks prior to migrating to the ocean to release her eggs. A female may produce 300,000 - 700,000 eggs per spawn, but very few larvae survive to become crabs. The larvae are an important food source for fish and other aquatic animals. Because there is concern about the giant land crab population, harvest is prohibited by law during the spawning season in Florida (from July 1 through October 31).  In Indian River County, these crabs are protected year round.