12 January 2016

Fearsome fiddlers?

Photo of a male fiddler crab Uca  from www.arkive.org

Judging a confident male fiddler crab, one can be easily captured by its unique, brightly colored, threatening enlarged claw. Fiddler crabs (Genus Uca) are major inhabitants of mud and sand flats along estuaries and sheltered coasts in the tropics and subtropics [1]. They may be small but their claws appear robust and powerful that you would not even think twice of its combating prowess. Or, should we?

Australian ecologists discovered this “bluff” in a group of fiddler crabs. The crabs use their massively enlarged claws for fighting over turfs as well for attracting females [1].  Once they lose a claw upon battle, they may grow another one, most of the time a replica of the original. The new claw, however, is a far cry to how they physically appear. It is lighter and toothless, rendering them weak and inferior [2].

Fighting ability is measured through major claw size, claw strength and the ability to resist being pulled from a tunnel. Crabs size up each other through their major claws, waving them in the air with surety. This means that physical make-up of the enlarged claw is detrimental in picking fights [2]. 

Now, to advertise one’s sex or to incite fight over territories, a crab will wave its regenerated claw, either up and down, others sideways, during low tide at territories established around their burrows [1]. Now, the wave is done and a fight may ensue. Unfortunately, the potential opponent, which is about to be fooled but is clueless of it, cannot distinguish the regular, powerful authentic claws from the cheap ones. The shining, regenerated claw is unfortunately void of any information on its fighting capacity. The opponent is then deceived and backs off. This remains true unless the crab with the regenerated claw holds territory and is trumped by a stronger opponent, revealing his bluff [2].

Knowing that this kind of dishonesty in the animal kingdom exists may provide an opportunity for ecologists to study dishonest signals. This discovery can also shed light on the individual reproductive success and survival among fiddler crabs by a thorough understanding of dishonesty mechanisms and consequences [2].

To know more about fiddler crabs, visit SeaLifeBase or come be a collaborator!

[1] Castro, P., & Huber, M. E. (2003). Marine Biology (4th ed.). Boston, Massachusetts: McGraw Hill.
[2] British Ecological Society (BES). Fiddler Crabs Reveal Honesty Is Not Always The Best Policy. ScienceDaily. ScienceDaily Retrieved from www.sciencedaily.com/releases/2008/11/081111203501.htm.

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29 October 2015


Dr. Daniel Pauly at a White House event on citizen science. (Source: Sea Around Us)

We take pride as SeaLifeBase’s Principal Investigator, Dr. Daniel Pauly speaks in the recently held discussion of the Oceans and Coasts session of the “Open Science and Innovation: Of the people, by the people, for the people”, a live-webcast forum of the White House held last September 30, 2015. The event was hosted by the White House Office of Science and Technology Policy (OSTP) and the Domestic Policy Council, having three objectives: (1) to celebrate the successes of citizen science and crowdsourcing; (2) to raise awareness of the benefits these innovative approaches can deliver and; (3) to motivate more Federal agencies and Americans to take advantage of these approaches [1].

In this forum, Dr. Pauly presented FishBase and briefly discussed the efforts of its project staff in the Philippines in gathering and extracting data from vast references in order to make information on all fishes become freely available to the world through the database. FishBase, an online information system founded more than 25 years ago, has grown to become one of the largest global database sources (GSDs) that provides systematic information on all fishes of the world including Etheostoma obama and Teleogramma obamaorum, two species of fish named in honor of President Obama. The database has received almost 50 million hits from over half a million users in a month and has been cited by more than 5000 scientific studies over the past decade, based from the Google scholar [2].

The forum was participated by respected citizen science professionals, researchers, stakeholders from different levels of the government, acadaemia as well as the non-profits and private sectors. It is such an honor for the whole FishBase team to be recognized as a successful science project by the White House. SeaLifeBase and  the whole FishBase Information and Research Group Inc. (FIN) family are very proud of what FishBase, with its founders, Dr. Pauly and Dr. Rainer Froese, have achieved.

Cheers! For future great collaborations that this opportunity might bring.

Watch the complete footage of the event here.

Links to other posts about the event: for Sea Around Us and for FishBase.


[1] Kalil, T. and D. Wilkinson.  Accelerating Citizen Science and Crowdsourcing to Address Societal andScientific Challenges. Published on September 30, 2015. [Accessed 10/22/2015].

[2] The FishBase Project Facebook page. Coming Soon: FishBase in the White House! Published on September 28, 2015.  [Accessed 10/22/2015].

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15 October 2015

Secret of resilience revealed in Antarctic octopod

Photo by Thomas Lundälv.

At a constant temperature of -1.8°C to 2°C in the Antarctic, ectotherms adapt various strategies to survive near-freezing temperatures. Such a condition may increase the solubility of oxygen but increase blood viscosity, making it difficult to deliver oxygen in tissues [1,2]. But such a dire circumstance does not thwart the Antartic octopod’s survival in freezing waters.

However, this octopod does not only thrive in cold temperatures, evidence suggests that a functional change in its blue-blood pigment ‘haemocyanin' enhances oxygen supply to octopod tissues, notably at higher temperatures. This could mean increased resiliency to warmer climate as global warming advances in the Antarctic Peninsula [1,2].

How does an Antartic octopod survive temperature extremes? Researchers analyzed the haemolymph of three octopod species – the Antarctic octopod Pareledone charcoti and the two species residing in warmer climates, Octopus pallidus and Eledone moschata. They found out that P. charcoti has one of the highest concentration of haemolymph recorded for octopods, allowing sufficient oxygen supply. Also, relative to the two other species, oxygen transport via haemocyanin in P. charcoti (76.7% on average) was significantly improved at 10°C compared to 0°C. Such a remarkable feat may allow the Antarctic octopod to thrive in both warm and cold temperatures [1]. Amazing, isn’t it?

To know more about these species and octopods in general, visit SeaLifeBase.

[1] BioMed Central. (2015, March 10). “Blue-blood on ice: How an Antarctic octopus survives the cold.” ScienceDaily. Retrieved March 16, 2015 from http://www.sciencedaily.com/releases/2015/03/150310205703.htm

[2] Oellermann, M., Lieb, B., Pörtner, H.O., Semmens, J.M., Mark, F.C. (2015). Blue blood on ice: modulated blood oxygen transport facilitates cold compensation and eurythermy in an Antarctic octopod. Frontiers in Zoology.

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