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Wetlands and Aquatic Research Center - Florida
Cruise Log: 8/14/2009
Taxonomy is fundamental to this project. We have to be able to identify the organisms that we bring up from the sub or in nets. We use physical characteristics to put a name with an organism. For example, we are studying Lophelia pertusa - a deepwater coral found worldwide. These scientific names are like our formal or "given" names. The ones we use to register for school or get our driver's license. These names are used around the world by all scientific researchers. We have a fairly new tool - DNA - to confirm these names, and help determine if minor differences in appearance are significant. For example: "Are two animals that have a similar shape and size but different colors the same species or not?" We also use DNA to confirm the way that we group individuals. Sometimes two animals that look very similar will be closely related, and at others times we find that they are not related at all. DNA can help create the "family trees" of living organisms.
We are lucky to have a taxonomist on board with us. Dr. Martha Nizinski is a taxonomist with the NOAA National Marine Fisheries Service. Her specialty is crabs, and we collect unusual species out here. Even with an untrained eye it is easy to see the difference between the galatheids and brachyurans. Generally the galatheids have long narrow bodies with skinny claws that don't appear to be very strong (but must be effective for catching their food). In addition to the claws, they only have 6 obvious legs - the last pair are modified and tucked under the tail. The one we have collected most frequently is Eumunida picta. These crabs have the common name of "Squat Lobster" - their nickname if you will. The brachyurans collected have a totally different structure - their carapace (or shell) is wider than it is long. They have 2 claws that appear to be very powerful, and not including their claws, have 8 additional obvious legs. They are much more similar in appearance to our common Blue Crab, but have a much thicker shell, robust body, and are lighter in color - their scientific name is Chaceon fenneri or "Golden Crab." Although these crabs are quite different, we know that they are related.
When we collect a specimen at sea, we usually take a photograph immediately in order to document the color of the animal. The color changes when the animal is preserved, and these images are one of the best representatives of the animal in the wild. We take a DNA sample that goes back to a lab for testing and analysis, and then the specimen is preserved with its label, identifying the date and location of collection. It is through these collections that we can document ranges of animals, habitats and changes over time. The Smithsonian has collections that date back to the 1800s and the North Carolina Museum of Natural Sciences has collections that date back to the early 1900s.
Taxonomists use these collections to gain an incredible amount of knowledge about the morphology (the form and structure) of specific groups of animals. They develop the dichotomous keys that are used to identify individuals. Dichotomous keys are a series of yes or no questions that help narrow down the range of possible choices that an animal could be. Keys start with broad questions, such as "does it have an internal skeleton" to the more specific "eight spines on the posterior margin of the shell (carapace)." Unfortunately for us, there are whole groups of animals without an expert in the field, or even an appropriate key to help us identify them. Some of the deep sea animals that we are collecting may not have been seen since they were first described. We compare the animals we have collected to those found in museum collections to help us determine the identity of the animals we have collected and what the correct name should be.
The data from the collections we make during this mission will add to the body of taxonomic knowledge of these species.
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