Fiddler crabs looking for mates on the banks in Capri
The most beautiful little hand-waving fiddler crabs have made their way in from the nearby marsh lands and are convening everywhere on driveways and in marshlands that boarder the Isles of Capri, putting on one of the most spectacular and impressive shows ever.
Hundreds of male fiddlers are seen raising their hands as if they were sure that they were the most appealing of all of their counterparts. They seemed to be saying, "Pick me, and pick me!" as they parade around the hundreds of females seen with them. This is one of God's little creatures that no one needs to ask, "Is it male or female?" The male has one enlarged claw that he uses to attract a mate by waving in front of her.
Fiddlers were named for the male's fiddler-shaped oversized claw, some of which are left-handed and others right-handed. During courtship and when repelling intruders from their territories, males raise their larger claw and it gives the appearance of playing a fiddle.
These little interesting and complex animals have two distinct mating strategies. One, females leave their burrows and move through the colony visiting many males before finding their match. Second, males wave vigorously to attract females to their burrow, where mating takes place underground. Little or no waving precedes surface mating, but when a match is made, the female incubates her eggs in a burrow.
Besides being entertaining to watch, fiddler crabs are an important component in our ecosystem. According to Zeil, Hemmi, and Backwell in Current Biology Volume 16, Number 2, these are the most recent marine animals to have invaded land. They are a rich source of food for birds, but more importantly, they play a much larger role in the intertidal ecosystem. They burrow into the marshland and sand along the coastal waterways and surrounding mangroves and feed on algae bacteria and detritus in the topsoil. Their burrows allow water to penetrate the substratum and thereby provide an oxygen-rich environment for soil microbes and mangrove roots. The mangrove roots in turn, hold back the land and protect it from the continuous rise and fall of the tides, and the microbes are an important food supply for marine life.
These seemingly playful little crustaceans, belonging to the genus UCA, are very similar to us in terms of their social behaviors. They live in a dynamic environment and constantly have to make decisions. They need to feed, maintain their burrows, establish and maintain relations with their neighbors, avoid predators, and pursue mating opportunities. Like us, they are excessive communicators, expert survivors and possess complex and flexible responses to the competing interests they face. They are extremely sensitive to bird-like objects flying overhead, and to crab-like objects that approach their burrows. They care about their neighborhood to the extent that they come to the aid of weaker neighbors and help them fight off burrow snatchers. This might be equated to Capri's Neighborhood Watch Program.
There are many lessons to be learned from fiddler crabs such as effective communication skills, working together to preserve our habitat, protecting one another, using resources wisely, and getting along with people from a vast number of backgrounds and experiences.
One of the most important contributions these fiddlers make to science comes from the fact that their rich behavioral repertoire is played out openly and in a very small space that can be monitored continuously.
Contact Ann Hall at firstname.lastname@example.org