By Gerardo Bolanos

What do sand dollars (sea stars) feed on? Sand dollars, which belong to the same class as sea urchins, sea stars and sea cucumbers, are carnivore animals that use a single cavity to ingest their food and then excrete it. They feed mostly on plankton and organic particles that sink to the sandy ocean bottom. Although these animals do not seem to move, they have multiple short appendixes on their bottom which they use to move slowly. When they are alive, sand dollars are covered by moveable spines.

What happens with red crabs during the dry season, when they disappear from the coast? Red crabs spend most of their lives in the coastal forests, with a maximum inland distance of 600 meters, feeding mainly on dead leaves and plantlings, although they can also be scavengers. During the rainy season, adult crabs migrate towards the ocean in order to reproduce. The female will lay its eggs in the water and the ones that are fertilized by a male will hatch. The little crabs will float like plankton for at least a month and then they will spend several months at the water’s edge looking for small particles on which to feed on. Adults are much more active during the rainy season, a time in which we notice them more often and also in which they are frequently run over while crossing the roads, having an important impact on their population.

Why do ants migrate from their nest so frequently? Army ants have the habit of being nomad which means that they migrate, or move, frequently. This is due mainly to the constant and high reproduction rate of their population. During certain periods, the larvae production demands large amounts of food, causing them to go out and “sweep” everything in their path in order to meet their basic food needs, thereby keeping their colony’s health. Although they are such small animals, their role in the ecosystem is extremely important since they help control the forest’s insect population and, in addition, the commotion they create when they pass by causes larger species, such as birds and mammals, to take advantage since insects are scared out of their lairs by them, making it easier for the larger animals to catch them. For this reason, ants are considered to “clean” the house of insect plagues.