Gulf Marsh Fiddler Crab, Uca longisignalis (Fiddler Crab of the Week)

The Gulf Marsh Fiddler Crab, Uca longisignalis, is found along the Gulf of Mexico coast of the United States, from northwestern Florida through Texas. It’s a medium-sized species, sometimes mixed up with close relatives such as Uca minax or Uca rapax. It has a medium to pale turquoise/blue carapace, brown legs, and a white/yellow major claw.

The name of this species (essentially “long signalling”) comes from its extended waving and acoustic display relative to similar species from which it was originally distinguished.

The Gulf Marsh Fiddler has not been the primary focus of many studies, although it has often been examined in comparative cross-species studies, particularly by Carl Thurman and his students and collaborators.


Bonin Islands Fiddler Crab, Uca boninensis (Fiddler Crab of the Week)

The Bonin Islands Fiddler Crab, Uca boninensis is fairly unique in that it is both endemic to the Ogasawara Islands of Japan (“Bonin Islands” is a historical name) and is not sympatric with any other species, being the only fiddler crab found on these islands. The only other fiddler crab with no sympatric fiddler associates is Uca tangeri, which has an immense range across most of the west coat of Africa and even the southern edge of Europe. There are a few other species endemic to small islands, but each of these overlaps with one or more other fiddler crabs.

Figure from Shih et. al (2013)

Until its recent description, this species was thought to be Uca crassipes. Shih et al. (2013) identified the new species through clear genetic differentiation between it and other populations of U. crassipes; they also found some minor morphological differences between these two very similar species, although nothing so striking as to allow easy identification. Little is known about the ecology of Uca boninensis since almost all previous work simply noted its presence on these islands. It is a medium sized fiddler crab, found in the upper intertidal zone of the estuaries of small rivers, in fragmented rock and muddy-sand substrates.

Because this species is known from only a few remote islands in the Pacific Ocean, its existence is likely threatened by climate change and is a candidate for conservation evaluation and protection. The Ogasawara Islands contain many endemic, unique, and endangered species across all forms of life and were added to the UNESCO World Heritage List in 2011.

Bowed Fiddler Crab, Uca arcuata (Fiddler Crab of the Week)

The Bowed Fiddler Crab, Uca arcuata, is one of the more widespread and better known species from eastern Asia, found along the coasts of China, South Korea, Taiwan, and Japan.  It is a large species, with a dark brown or maroon carapace (often with cream edges and highlights), cream eyestalks, black-to-red legs, and a robust major claw with a red hand and cream fingers.

In parts of its range, both males and females of this species build chimneys around the mouths of their burrows, extending the entrance upward from the muddy surface. They are often found on open mud flats and banks near the mouths of rivers. This species has been the focus of many studies by marine ecologists in both China and Japan.

Jocelyn Crane reported that this species could sometimes be found canned in local seafood markets in Japan, making it one of only two species eaten by humans.

Word Cloud of Names

I recently happened to stumble across the lab page of a faculty member who used a word cloud based on his research papers to display the key words that come up most often in his own research. I thought this was a rather interesting way to get an objective view of ones research so started playing with the idea for my own work. Unfortunately, this turned out to be more difficult than I expected, not because building a word cloud was hard (there are plenty of available tools for that), but because extracting the text from the PDFs of all of my publications led to a lot of weird biases and errors (this is a PDF issue) and it’ll take a lot more effort to dig up the original raw text documents than I’m willing to go through right now.

It occurred to me secondarily, however, that we could use the same approach on the fiddler name data to get a visualization of how often each name appears in the literature.

First we have the occurrences of binomial/compound names in the literature. The frequencies are based on the number of publications each name appears in if used as a valid name (thus, a paper which states that name A is a junior synonym of name B would only count the senior synonym B and not the junior synonym A). No matter how many times the name is used within the paper, it counts as only one occurrence with respect to this exercise.

The results are pretty much what one would expect, but it does provide a somewhat interesting (if not particularly statistical) rendering of the relative name uses.

As with other parts of the site, we can do the same thing with the specific names only (ignoring both genera and lumping alternate/misspellings). Again, the major names are what one would expect.

I may need to play with the visualization a bit (color schemes, shape, etc.), but these images will be added to the name summary part of the website on the next monthly release.


Beebe’s Fiddler Crab, Uca beebei (Fiddler Crab of the Week)

Note: the fiddler crab of the week series was temporarily derailed due to some unexpected health issues, but will hopefully be back on track going forward.

This week we find another species from the Pacific coast of the Americas, Uca beebei, named after the famous naturalist, explorer and author William Beebe. This small species is found from El Salvador through Peru on open mudflats. In the Pacific entrance of the Panama canal it tends to be one of the more numerous species, often found mixed with larger species such as Uca stylifera or Uca heteropleura or more similarly sized species such as Uca deichmanni. Relative to many other species, it is also more of a generalist when it comes to substrate preference, ranging across both sandier and muddier mudflats. Not the most colorful species, it tends to be a grayish-brown with some teal on the back of the carapace; the long, slender fingers of the large claw are white, while the rest of the major limb often has dark purple highlights. The eyestalks are thick and yellow.

Photo provided by Pat Backwell.

Unlike many of the other species in the series so far, Uca beebei is actually fairly well studied. John Christy and colleagues spent many years studying the behavior of this species in Panama. It has a fairly classic, basic wave, quickly moving laterally its claw to the side, then forward in an overhead circle back to the rest position. The small claw often goes up and down as well. The waving can be done either standing in place or sometimes shuffling toward or away from another crab.

Beebe’s Fiddler Crab is one of a number of species which build structures around the mouth of their burrow. As seen in the photo below, the males build a sort of wall or pillar or partial hood on one side of the burrow opening. The exact purpose of these structures is unknown, but in part it seems to be used as a beacon to allow themselves to find their burrow more quickly if they’ve wandered away from it.

Photo provided by Pat Backwell.