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Due to the huge number of insects, spiders and other invertebrates on Nevis, these pages will be subject constant updating as information for the Biodiversity Project becomes available and is transcribed onto this website. If readers have any relevant articles, photos or other pertinent information on this subject please let us know as we would appreciate the feedback.
Invertebrates The treatment of invertebrates in this website is weak at present, which is unfortunate given the projects focus on biodiversity and the fact that worldwide invertebrates comprise more taxa than the better-studied vertebrate animals. For most of us, however, our knowledge of the “lower” forms of life is inadequate to even provide a perspective for evaluating the data and data gaps. For example, there are some data on West Indian amphipods (small crustaceans) because of the work of a Dutch scientist who started collecting in the region in the 1930s and continued for nearly half a century. Many of the thousands of samples collected from Aruba to Florida during the Hummelinck expeditions have been sorted, but fewer have been thoroughly classified. So far five families have been identified. Is this a lot or a little? To rephrase the question more scientifically, issues such as the following need to be considered: - How many families of
amphipods are there globally, i.e., how well represented are they in the
Caribbean from a global perspective? In a sense, the last question is the starting point. For example, from our study of bird species, we know that St. Kitts-Nevis has approximately 130 species of birds, and we have an intuitive sense of what this means in terms of avian biodiversity. While most of us might not know that there are approximately 9,600 species of birds that are known to science, our guess would probably be within an order of magnitude in either direction; i.e., between 1,000 and 100,000. Thus, we have a sense of what it means for St. Kitts and Nevis to have about 130 species of birds. To be able to do the same sort of thing with amphipods would require that we know something not only about their diversity, but also about their taxonomic relationship to other organisms. Amphipoda is an order containing some known 6,000 species that range in length from tiny 1-mm forms to deep sea benthic species reaching 25 cm. They have invaded most marine and freshwater habitats, but can also occur in moist forest leaf litter, gardens and sandy beaches. The order Amphipoda joins 15 other orders to form the class Malacostraca—a diverse grouping of some 20,000 species of organisms that include a planktonic shrimp-like creature smaller than 1 cm that lives more than a mile beneath the surface of the sea, as well as the economically important shrimp, crabs and lobsters. The Malacostraca are 1 of 5 classes, that together contain some 30,000 species comprising the subphylum Crustacea; within the phylum Arthropoda. There are several million species of arthropods known to science (and good reasons to believe that there may be 20-50 million more that remain to be discovered). And Arthropoda is just 1 of more than 20 phyla of invertebrates that along with the phylum Chordata (which contains all the vertebrates as well as a few invertebrate taxa) comprise the kingdom Metazoa (animals). This basic traditional classification scheme—species, genus, family, order, class, phylum, kingdom—is still used today for convenience, such as in the discussion of amphipods above; but it implies a hierarchy that is more rigid than many taxonomists accept, and many use a wider range of taxonomic categories, referring to them variously as “taxa”, “modes”, “types”, “groups”, etc. The disagreements are not only over the names of the taxonomic units, but more importantly, over the relationships among the organisms (i.e., their phylogeny). Differences that may seem esoteric in some contexts take on heightened importance within the realm of biodiversity conservation. The section on invertebrates that follows is illustrative, but obviously it cannot be comprehensive. Interested readers are referred to Brusca and Brusca’s (1990) text Invertebrates, which provides a taxonomic system that is used in Table 5. Note that Brusca and Brusca (1990) differentiate 29 phyla or equivalent taxa comprising the Metozoa; but there are several other classification schemes that also have large followings within the scientific community (one interesting scheme that is particularly “user-friendly” is Maddison and Maddison’s Tree of Life website <http://phylogeny.arizona.edu/tree/phylogeny.html>). The reasons for these different viewpoints are as informative to our understanding of biology as the information they present, but clearly it is beyond the scope of this document to elaborate on this theme. One of the few
invertebrate groups that has received substantial attention in the Caribbean is
the Coleoptera. The notes that follow, paraphrased from discussions with Dr.
Michael Ivie, an entomologist who has worked extensively in the Virgin Islands,
offer an interesting and valuable perspective: Based on data from the better-studied islands [Table 4], we know that the area and elevation of an island seem to be the best predictors of its species diversity. Thus, St. Kitts, which is larger and higher than St. Thomas, should have more beetle species, yet it has less than 10% of the number known for St. Thomas. Redonda, with 1 known species, would be expected to have more species than Guana, BVI, which has 250 catalogued species. In the Virgin Islands, we have identified some 1400 species; 50% or more of the species on each island are endemic to that island, or at least to that island bank (i.e., the land mass that would have been exposed above sea level during the low-water maximum of the Pleistocene period; i.e., ~200m contour). The Northern Leewards area (from Sombrero, Anguilla to Montserrat) probably contains well over 1,000 undescribed, undiscovered species (and many genera) of beetles alone on the 8 separate Pleistocene banks. Terrestrial Biodiversity Implications Given the impossibility of knowing the population size and distribution of every species found in the country, an effective approach to identifying some of the critical biodiversity conservation priorities might be to concentrate research on selected taxa. Ivie’s data imply that the best candidates are the vascular plants and at least one of the insect orders. Given the well-established evolutionary and ecological relationship between plants and insects, the inventories would target as many different plant communities as could be identified. Our most effective measure to safeguard the biodiversity of plant species and terrestrial invertebrate biodiversity would be to protect, to the fullest extent possible, representatives of all the different vegetation communities. As this website is very much a work in progress, we welcome any additional materials, photos, corrections or suggestions readers may have. We also plan on adding a dedicated photo gallery to highlight the "Flora & Fauna of Nevis" in-depth, and readers contributions are welcome!
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