Today’s Highlights

• K2 made two dives within the newly established Marine Protected Area (MPA) called “The Humps” in the eastern Pourtalès Terrace.
• John Reed and Andrew David (NMFS Lab in Panama City) observed larger numbers of fishes than on any previous dives, including aggregations of snowy grouper, barrelfish, big roughy, and schools of well over a hundred boarfish.
• Some of the attached invertebrates, including a small delicate primnoid sea feather, appeared and later disappeared from the seafloor community without any obvious change in bottom conditions or topography.
• For daily expedition images, visit CIOERT Flickr collection at: http://www.flickr.com/photos/cioert/.

How Do We Know What We Are Seeing?

Charles G. Messing, Professor, Nova Southeastern University

As a taxonomist specializing in marine invertebrates, one of my jobs on this expedition is to help identify the organisms we observe.  Although taxonomy itself focuses on the identification and classification of organisms (both living and fossil), it lies within the greater context of evolutionary biology, of our efforts to understand the pattern and history of biodiversity.  Perhaps the first question anyone asks in a new habitat is: “What is that?” or “What are those?”  The easiest answer is to offer the name of the major group to which the creature belongs.  “It’s a sponge” or “Those are sea fans.”  But, answers like that, although pointing in the right direction, are not at all final. Imagine viewing a vast assemblage of antelopes, zebras, giraffes, and buffalo on the east African plains and having someone tell you: “Those are mammals.”  So, we have to be more specific whenever we can.  We categorize organisms via a hierarchical system of classification, with smaller groups nested within larger ones, like Russian dolls: species within genera (the plural of genus), genera within families, and so on to the largest subdivisions: phyla (plural of phylum) within kingdoms (and, recently, kingdoms within realms).  When the Swede, Carl Linnaeus developed this system about 250 years ago, he could not have realized that, a hundred years later, it would provide the scaffolding for Charles Darwin’s new evolutionary approach to understanding life: that, for example, species in the same genus are not only more closely related to each other than they are to species in another genus, but that they share a more recent common ancestor than species in another genus.

The Pourtalès Terrace supports an amazing diversity of sponges. Several on a ledge include two pale fluted bouquets of Leiodermatium, which produce a chemical that has powerful antitumor activity and is currently being investigated for pharmaceutical use. (Photo Credit: CIOERT, taken from UCONN's K2)

Whenever we see a creature in the ROV’s view, we work down through Linnaeus’ hierarchy.  Of course, in most cases this is automatic.  When we (or you) see a fish, we don’t consciously think, “OK, that’s an animal, a vertebrate, a bony fish (or cartilaginous fish, if it’s a shark).  We “know” from what we have learned that it is indeed a fish.  We analyze all of its features, those of its kingdom, phylum, class, order, family (and, if we’re experienced enough), genus and species together.  (Deciding what is a fish in scientific terms is actually not that straightforward.  It turns out that lungfishes are more closely related to us than they are to salmon, but that’s another discussion.)

Marine biologists observing the sea floor (or botanists in the Amazon rain forest) bring to their work an extensive mental encyclopedia of classification that allows us to put names to the creatures we see.  But, it is often difficult or impossible to identify organisms to species or genus, or even family.  Many organisms, particularly many of the seafloor invertebrates such as sponges, gorgonians, and lace corals, require a specimen in hand, often for examination of characters that can only been viewed under the microscope.  As a result, the narration you hear coming from the scientist sitting at the K2 console may sound like: “Those are stylasterids [family]; there’s a big Geodia [genus]; I’m not sure, but that’s some kind of demosponge [class].”

A pair of delicate salmon-colored stylasterid lace corals, each about 20 cm across near the edge of a limestone ledge at a depth of 200 meters. Every one of the thousands of colonies of these corals grow at right angles to the prevailing bottom current, which here flows into the image. (Photo Credit: CIOERT, taken from UCONN's K2)

When we do manage to collect a specimen, that’s often not the end of it.  There are between 25 and 30 phyla of animals in the marine environment, and most taxonomists have expertise in only one or two, often only in one subgroup.  So, we bring along a floating library of scientific publications that may help narrow the alternatives.  My area of expertise is the Crinoidea, the sea lilies and feather stars.  However, I just set myself up to put a name to two of the lace corals we collected.  I dug out John’s copy of Stephen Cairns’ 1986 “A Revision of the Northwest Atlantic Stylasteridae”, which includes descriptions and illustrations of all known species in the region.  Of course, every group of organisms has its own descriptive terminology.  For the non-specialist, it may be like trying to decipher a foreign language, in this case, for example, words like dactylopore, coenosteum, and gastrostyle.  First, I looked at the distributions of all 42 species and found that only seven had been previously collected from the Pourtalès Terrace (although I kept an eye on several more known only from off northern Cuba).  Despite the new vocabulary, there were enough measurements and recognizable features that allowed me to get to the genus level with some certainty: Distichopora and Pliobothrus.  I’m still a little fuzzy about the species, but D. foliacea and P. symmetricus are the only species in their respective genera that are well known from our area.

If it turns out, for example, that some organism produces an important biomedical compound, we will always try to verify our identification with an expert who has seen many specimens of many closely related species and understands their variations.  It was, after all, the variations within and between species that Darwin focused on in developing his theory of evolution by natural selection.  If I find variations that make it difficult to determine which species I have, it’s not surprising.  A species is both a pattern that varies in space across its range under different environmental conditions, and a process that takes place through time.  Species diversify over time into more species, and an important line of evidence supporting evolution is that we often cannot tell where one species begins and another leaves off.

Want to know more?

See:http://cioert.org/flosee/blog/center-of-marine-biomedical-and-biotechnology-research/ for a blog written by Kathleen Janda and Tara Pitts, HBOI-FAU, during our 2010 Florida Shelf Edge Exploration (FLoSEE), about how HBOI scientists isolate novel natural products from sponges, soft corals, and other invertebrates.