The galatheoid Eumunida picta is commonly known as the "squat lobster." The lasers on its legs are three inches apart. In the background, we see Asteroschema sp. wrapped around the sea fan, Callogorgia sp. Click image for larger view and image credit.
Squat Lobsters: More Questions Than Answers
September 27, 2008
Morgan Kilgour
Harte Doctoral Fellow
Harte Research Institute
Texas A&M University-Corpus Christi
In the world of marine animals, crustaceans are often overlooked. Most people would rather study a dolphin or a sea turtle. I have never encountered anyone young who is wild about crabs. (Even our pet hermit crab pales in comparison to the popularity of the cat or bird.) Sure, crabs are good to eat, but who would want to devote a lifetime to understanding them?
To understand the complex nature of our oceans, we must include the study of crabs. Crustaceans serve as an integral part of the ocean around them. One type of crab, the Galatheoids, or squat lobsters, are part of the interconnected deep-sea society, and we have more questions about them than answers.
Galatheoids are found throughout the world in waters that range from shallow to deep — even thousands of meters below the surface. There are over 60 species of galatheoids in the Gulf of Mexico. They are members of seep assemblages and deep coral reefs and can be found in burrows on the soft sediment. We know these animals are predators, scavengers, and detritivores (an organism that feeds on dead plant and animal matter), but we still have only vague notions of exactly what they eat, what eats them, and what they do in the deep oceans. In fact, most of the information we have on deep-sea galatheoids focuses solely on the description of new species.
Reproduction in galatheoids is also a mystery. Some have large eggs, some have small eggs; males may be larger than females, females may be larger than males, or they might be the same size. (Difference in size, based on sex, is called “dimorphism.”) We have a lot more work to do to discover the intricacies of how these anomurans (squat lobsters) live, how they reproduce, and what they contribute to their communities.
An Eumunida picta nestled in Lophelia rubble. Click image for larger view and image credit.
This squat lobster challenges the remotely operated vehicle. Click image for larger view and image credit.
Previous studies in the Pacific found that galatheoids (of the same species) on similar habitats that were tens of kilometers away are more related to each other than galatheoids (of the same species) just a few kilometers away on a different habitat (soft substrate). How could this be the case? Some larvae may broadcast widely. Could other larvae be retained close to where the parents are, or are they selecting for similar habitats as those of their parents? Would this cause the species to diverge eventually into two different species?
We have much to do before we can begin to understand these animals. With each new visit to the deep, we are excited to possibly solve another piece of the puzzle. The more answers we have, the better we can serve as protectors of the deep sea.
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