Background
Traditional (local) communities retain detailed knowledge about the biological resources of their surrounding environment. The experiences, knowledge, and knowing-doing accumulated by these communities about the natural and supernatural worlds and which is transmitted orally through the generations, characterizes traditional or local knowledge [
1‐
4].
Studies concerning traditional knowledge are themes of the ethnosciences – a branch of study that arose as a fusion of fields and that has continued to evolve in the exchange between the natural sciences and the human/social sciences [
5]. Ethnoscience grows with each day, but it also tends to fragment into sub-areas (like most of modern science) – in contrast to the communities under study, which don't tend to fragment their knowledge. As such, ethnobiology is a sub-area of the ethnosciences that seeks to understand and analyze the way in which living things are perceived, known, and classified by diverse human communities [
6,
7]. Research directed towards the various areas of the ethnosciences (ethnobotany, ethnoichthyology, ethnobiology) have come to age in the scientific world and have contributed to recent investigations into the knowledge of traditional populations [
2].
Ethnobiology can be still further subdivided into folk taxonomy or ethnotaxonomy – which studies how traditional communities classify, identify, and name their natural resources. According to Lévi-Strauss [
8], human populations have an apparent intellectual necessity to classify the natural world because it is inherent in humans to demand order. Humans respond to plant and animal diversity in their environment by grouping these living organisms into named categories that express differences and similarities between them, and also group them into classificatory categories of greater or lesser inclusion [
9,
10].
One of the authors that most stands out in terms of studies of folk taxonomy is Brent Berlin [
11] who developed twelve general principals of ethno-biological classification and naming – of which seven are directed towards classification and five towards naming. Among the basic principals proposed by Berlin [
11], those that refer to structural hierarchies especially draws our attention – with plants and animals being ordered in a way that establishes hierarchies comparable to those of Linnaean taxonomy [
3], with hierarchical categories organized on the basis of principals of inclusion and exclusion, strictly separated and included in more general categories [
12]. Many studies throughout the world have demonstrated that the folk classification of animals and plants consist, quite often, to the scientific classification of those organisms and this coherence demonstrates that these classifications are not arbitrary cultural workmanships, but are determined by some degree of biological reality or universal cognition [
13]. According to Berlin [
14], ethnobiological classifications start with the principal of universality among the different cultures, where there are consistencies in the classification and naming of plants and animals among traditional populations.
Studies of folk taxonomy allow the interaction of the ethnobiological knowledge of traditional populations with more formal scientific knowledge and seek to better understand the diversity of these communities and their relationship with their natural environment [
7]. Similar to scientific taxonomy, ethnotaxonomy retains a vast store of information about biology, ecology, and ethology of both animals and plants [
15]. The ethnobiological classification system can be used as a tool for a rapid assessment of biodiversity [
16], can also contribute to a great deal of new information about the natural resources and even assist in new taxonomic discoveries. Folk taxonomy not only organizes and condenses biological information but it also provides a powerful systematic tool to examine the distribution of biological and ecological properties among organisms [
17].
Also according to Castro [
18], the classificatory systems of "traditional" populations make up part of their cultural patrimony and their relations to the natural world are manifested in their vocabularies and in the terms the use to translate their experiences and adaptations to the environment around them. As such, ethnotaxonomic studies are important in that they help preserve and conserve the biological and cultural diversity that is reflected in the traditional (usually oral) knowledge of these communities It is important to understand the local diversity in order to get an efficient conservation and management of the resources
The present work examined the folk taxonomy of the crustaceous gatherers of the communities of Barra de Mamanguape and Tramataia on the Mamanguape River Estuary (MRE), Paraíba State, Brazil, in which we analyzed the classification criteria used for the crabs and swimming crabs of that region.
As most of the crustaceous gatherers and fishermen of the region still dedicate most of their lives to manual collecting and fishing, they retain an enormous empirical knowledge about the resources of the region. This traditional knowledge should be respected and consulted when management activities are planned for a given region, and ethnobiological and ethnoecological studies can aggregate the value of their local knowledge and culture to more formal scientific endeavors.
Appendix 1
Emic identification key for the crabs and swimming crabs (generic polytypics).
ARATU
"They are red, the youngest are black and have hairs on their fingers. They're smaller than the "caranguejo uçáu". They have one large and one small claw. They walk on tip-toes. They are more common in the mangrove swamp where they stay in the trees."............................................................................................ ARATU DE MANGUE
...............................................................................................................Goniopsis cruentata
"They have a rounder shell, their fingers are longer than those of the "aratu do mangue". They are squat. All of their feet are the same size. They are gray and white below their chest and their fingers. Larger, meatier, taste like lobster, dark brown like sargasso, mud and live among the rocks, only on the reefs." ........................... ARATU DE PEDRA
...................................................................................................................Plagusia depressa
CHAMA-MARÉ
"They're different than those at the tide's edge, the claw is larger and thinner, they live in the mangrove swamp."................................................... CHAMA-MARÉ DE MANGUE
............................................................................................................................Uca burgesi
"Very white or yellow and small, live at the edge of the surf."................................................................ CHAMA-MARÉ DA BEIRA DA PRAIA
....................................................................................................................................Uca sp.
"They have a red claw, and live at the edge of the croa (mud banks) and at the edge of the surf where there is mud."..............................................CHAMA-MARÉ TESOUREIRO
.......................................................................................................................Uca maracoani
DORMINHOCO
"They live in the mangrove swamp and are darker."...DORMINHOCO DO MANGUE
................................................................................Panopeus lacustris/Eurytium limosum
"They live among the rocks and are lighter than the "dorminhoco do mangue." .........................................................................................DORMINHOCO DAS PEDRAS
.................................................................................................................Menippe nodifrons
GOIAMUM
"They are very blue, the color of aniline or light blue. They're larger than the "goiamun caboclo.".........................................................................................GOIAMUM AZULÃO
.............................................................................................................Cardisoma guanhumi
"Bright blue with yellow"............................................................GOIAMUM CABOCLO
.............................................................................................................Cardisoma guanhumi
SIRI
"They're blue and large, and live in the mangrove swamp."................................................................................................................SIRI AÇÚ
..........................................................................................................Callinectes exasperatus
"They are long and their shell has very thin teeth. You catch them during the tide. They're meatier and light blue."..............................................................SIRI PONTINHA
...................................................................................................................Callinectes danae
"They are the biggest. Smell like shit when you cook them, they have one reddish claw, they are dark and rusty-colored. They live in fresh water and in pens."..................................................................................................... SIRI CAGÃO (M)
...............................................................................................................Callinectes bocourti
"Fat, somewhat reddish. Live in freshwater."....................................
SIRI NEMA (F)
...............................................................................................................Callinectes bocourti
"Completely red, the color of malagueta peppers. They burn, just like hot peppers."They live on the rocks and on the edges of the tide which has some stones.".......................................................................................
SIRI PIMENTA
...............................................................................................................Callinectes larvatus
"They are brownish with white spots, the same color as the guiné plant. Live among the rocks."..................................................................... SIRI PINTADO/SIRI DAS PEDRAS
................................................................................................................Arenaeus cribrarius
Legend: M – male; F – female.
Competing interests
The authors declare that they have no competing interests.
Authors' contributions
ENF collected and analyzed the data, realized the discussion, identified some specimens of the crabs and wrote the manuscript. JSM designed the study, conducted the framework, supervised the research, revised the manuscript and assisted in the taxonomic identification of the some specimens. PDR collected the data and realized the register photographic. DMN and DMMSQB collected the data. All authors read and approved the final manuscript.