What are fiddler crabs?
-Fiddler crabs are a type of crab named after the feeding of the males, where the movement of the small claw from the ground to its mouth resembles the motion of someone moving a bow across a fiddle (the large claw).
-Fiddler crabs have oblong/rectangular bodies with two claws; A small and an enlarged pincer
-The shorter claw/pincer can be up to one inch
-The major claw/pincer can be up to 2 inches long
-There are 106 species of fiddler crabs including the Uca Minax which is a specific subspecies
-The Uca Minax is characterized as:
-being a chestnut brown with a gray color in the front
-the claws of this crab have red joints
-they have eight walking legs that are either olive or grayish brown in color
-near the center of the shell, called the carapace, there is a H-shaped depression
-Fiddler crabs diet consist mainly of algae, fungus, and detritus (decaying plant/animal matter) that is scraped off sand particles
-This feeding process is one one of the fiddler crab’s main benefits to an environment as it acts as a living filter
-Fiddler crabs live in beaches and wetland in burrows
Lifecycle
Fiddler crabs go through four official stages during their lifetime excluding final adult/death stage.
Egg
This is the first stage where a female fiddler crab, also known as a sponge crab, will become fertilized and carry hundreds to thousands of eggs in her abdomen. This stage lasts around two weeks before the female lays her eggs.
Zoaea
The female will lay her eggs in water and the time of day that this occurs is dependent on the flow and ebb of tides in that specific environment. For example, the Uca thayeri, a species exposed to East Florida’s coast, lays there larvae at night due to the semidiurnal, twice a day, tides. Once the female has laid her egg they become microscopic free-swimming larvae. A zoaea is simply the term used to describe the first series of the molting stages.
Megalopa
The larvae will continue to live in the water and off of the plankton species. As the larvae continue to grow over a period of a few weeks to a few months depending on the subspecies, they go through a number of different molting periods. These older larvae are known as megalopa.
Crab/Adult
At the end of the previous stage the megalopa become “immature” crabs that then move to land and become classified as “juveniles.” Juvenile crabs and adult female
crabs are similar due to their size and lack of asymmetric claws. As the juvenile crabs continue to grow they gain more obvious sexual signifiers such as the asymmetric claws and more ornate coloring.
Feel free to click on the below picture to access a video pertaining to fiddler crabs!
Fun Facts about Fiddler Crabs
Fiddler crabs move in groups of thousands when feeding!
They are omnivores meaning they eat plants and animals.
Fiddler crabs are also scavengers which means that they eat the remains of other species.
A male fiddler crab’s life expectancy is around three years while the female’s is only two years.
They are a type of Crustacean.
They are able to regrow their ligaments, meaning their arms and legs, whenever they molt!
They can only walk sideways.
Fiddler crabs are able to communicate with one another through a series of waves and gestures.
The purpose of the enlarged claw that the males possess is to fight over reproductive mates.
Fiddler crabs burrows can go as deep as two feet!
Thank you so much for reading my Week 4 upload on fiddler crabs, specifically the Uca Minax! With the instatement of in person learning for all grades going into effect I hope to work with you all soon!
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