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Um Éon De História Dos Bivalvia: Ideias Sobre a Sua Origem, Filogenia E Importância Paleontológica E Educativa

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Um Éon De História Dos Bivalvia: Ideias Sobre a Sua Origem, Filogenia E Importância Paleontológica E Educativa Um Éon de história dos Bivalvia: ideias sobre a sua origem, filogenia e importância paleontológica e educativa Ricardo J. Pimentel1, Pedro M. Callapez2 & Paulo Legoinha3 1 Agrupamento de Escolas de Guia, P-3105 075 Guia, Pombal, Portugal. E-mail: [email protected] 2 Universidade de Coimbra, CITEUC - Centro de Investigação da Terra e do Espaço da Universidade de Coimbra, Faculdade de Ciências e Tecnologia, Departamento de Ciências da Terra, Polo II, Rua Sílvio Lima, P-3030 790 Coimbra, Portugal. E-mail: [email protected] 3 Universidade NOVA de Lisboa, GEOBIOTEC - GeoBiociências, Geotecnologias e Geoengenharias, Faculdade de Ciências e Tecnologia, Departamento de Ciências da Terra, Quinta da Torre, P-2829 516 Caparica, Portugal. E-mail: [email protected] Resumo: A Classe Bivalvia, cuja monofilia se encontra bem suportada por estudos recentes, destaca-se como o segundo taxon, em termos de biodiversidade, do Filo Mollusca. O registo da sua história evolutiva remonta ao Fortuniano (Câmbrico). Diversos dados paleontológicos fundamentados no registo fóssil sugerem que os bivalves atuais são, sobretudo, herdeiros de carateres morfológicos e requisitos ecológicos transmitidos por linhagens da transição devónico-carbonífera. Estes invertebrados habitam a maioria dos ambientes aquáticos atuais e constituem um dos principais grupos de animais invertebrados da biosfera atual, são herdeiros de uma longa história evolutiva e ecológica que é intrínseca à própria história biótica dos oceanos durante o Fanerozoico. São um exemplo de sucesso entre as comunidades bióticas e a sua abundância, diversidade e acessibilidade propiciam a sua utilização como recursos educativos em Ciências Naturais. Palavras-chave: Bivalvia, Educação científica, Filogenia, Mollusca, Registo fóssil. Abstract: The Class Bivalvia stand out as the second taxon in terms of biodiversity of the Phylum Mollusca, and reveals a monophilia well supported by recent studies. The record of its evolutionary history dates back to Fortunian (Cambrian). Several palaeontological data based on fossil record suggest that recent bivalves are Abrantes, I., Callapez, P. M., Correia, G. P., Gomes, E., Lopes, B., Lopes, F. C., Pires, E., & Rola, A. (Eds.), Uma visão holística da Terra e do Espaço nas suas vertentes naturais e humanas. Homenagem à Professora Celeste Romualdo Gomes. Coimbra: CITEUC. © CITEUC, 2020 DOI: http://doi.org/10.5281/zenodo.4411523 Ricardo Pimentel, Pedro M. Callapez & Paulo Legoinha essentially the heirs of morphological characters and ecological requirements transmited by evolutive lines of the Devonian-Carboniferous transition. These invertebrates inhabit most recent aquatic environments and constitute one of the main groups of invertebrate animals of the biosphere. They are heirs of a long evolutionary and ecological history that is intrinsic to the oceanic biotic history during the Phanerozoic, being an example of success among biotic communities. Their abundance, diversity and accessibility enable their use as educational resources in Natural Sciences. Keywords: Bivalvia, Science education, Phylogeny, Mollusca, Fossil record. Introdução Os bivalves (Filo Mollusca, Classe Bivalvia) são animais invertebrados lateralmente comprimidos, sem região cefálica diferenciada, cujos tecidos moles são protegidos por uma concha externa formada por duas valvas simétricas ou assimétricas entre si, as quais se apresentam ligadas e articuladas dorsalmente, conferindo ao corpo uma rigidez apreciável. Esta tipologia morfológica relativamente simples e arcaica constitui uma estratégia de sucesso entre os organismos aquáticos, estando também presente noutros grupos taxonómicos tais como os braquiópodes e os ostracodos. Permite, entre outros aspetos, um certo grau de proteção contra predadores ou condições desfavoráveis do meio. Em virtude de muitas das espécies atuais serem generalistas, sem grandes requisitos ecológicos restritivos, os bivalves estão representados em todos os ecossistemas aquáticos, desde os marinhos profundos, ou os hipersalinos, até aos de água salobra e aos dulçaquícolas. Ocupam uma extraordinária variedade de nichos em habitats marinhos desde o andar litoral até aos fundos abissais, incluíndo microambientes tão díspares como as chaminés hidrotermais e os escoamentos submarinos de hidrocarbonetos. Não obstante, a sua diversidade é maior em ambientes costeiros, dentro da zona fótica. Desta forma, a utilização dos bivalves para fins pedagógicos e educativos pode constituir um importante recurso em Ciências Naturais. Aristóteles (384-322 a.C.), na primeira e quarta partes do seu quarto livro da obra História dos Animais (Τῶν περὶ τὰ ζῷα ἱστοριῶν), foi provavelmente o primeiro naturalista a deixar registo relativamente aos bivalves. Na sua classificação artificial para os animais, colocou-os nos seres destituídos de sangue vermelho e, dentro deste grupo, num terceiro “género” que designou por ostracodermes ou testáceos (MacGillivray, 1834). Aristóteles entendia como bivalves os ostracodermes cobertos por duas “conchas” (Aristóteles in Silva, 2006), os Dithyra, sendo os restantes organismos do grupo constituídos pelos atuais gastrópodes e equinoides. No entanto, a designação Bivalvia, tal como a reconhecemos hoje, remonta, pelo menos, a 1681, quando Filippo Bonanni (1638-1723) publica a profusamente ilustrada Ricreatione dell'occhio e della mente nell'osservation' delle chiocciole: proposta a'curiosi dell opere della natura (Fig. 1A,B), onde surgem as primeiras referências a bivalves oriundos da costa portuguesa (i.e., Bonanni, 1681, pp. 158, 160, 165, 168) (Pimentel, 2018). Um Éon de história dos Bivalvia: ideias sobre a sua origem, filogenia e importância paleontológica e educativa Esta designação seria adotada por Carl von Linné (1707-1778), na décima edição da sua obra Systema naturae: per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis (Linnaeus, 1758, p. 645). Outras designações, consideradas sinónimas, foram usadas por diversos naturalistas (e.g. Ditoma Tournefort, in Gualtieri, 1742; Acephala 1 Cuvier, 1795; Conchifera Lamarck, 1818 2 ; Pelecypoda Goldfuss, 1820; Lamellibranchiata Blainville, 1824; Elatobranchia Menke, 1830). Figura 1 - A, B. Fac-símile de frontispícios da obra, com referência aos bivalves, Ricreatione dell'occhio e della mente nell'osservation' delle chiocciole: proposta a'curiosi dell opere della natura (Bonanni, 1681) [Fonte: https://doi.org/10.5962/bhl.title.119125]. Os bivalves encontram-se ligados inexoravelmente ao Homem, enquanto recurso alimentar, desde as práticas de subsistência recoletora, no contexto de grupos ou comunidades paleolíticas e mesolíticas, até às atuais produções massivas em aquacultura de moluscos. Também nos trazem preocupações de carácter sanitário, já que podem acumular toxinas, derivadas de dinoflagelados e diatomáceas, bactérias, vírus e metais pesados. Alguns bivalves perfuradores (teredídeos e foládios lignívoros) acompanharam os marinheiros ao longo dos séculos, tendo grande impacto na duração e resistência estrutural de navios e equipamentos litorais construídos em madeira. 1 Lankester sugeriu o termo Lipochefala (Woodward, 1913, p. 26). 2 Relembre-se que Conchifera Gegenbaur, 1878, possui um significado taxonómico muito mais abrangente em relação aos moluscos testáceos. Ricardo Pimentel, Pedro M. Callapez & Paulo Legoinha Sendo Portugal um país bafejado por uma extensa orla costeira com numerosas arribas, praias, estuários e lagunas, para além de uma intricada rede de nascentes e cursos de água, existem amplos recursos e oportunidades à disposição de professores e alunos dos diferentes graus de ensino, para que centrem projetos em problemáticas relacionadas com bivalves. Estes podem constituir o tema aglutinador de interessantes projetos de estudo e pesquisa interdisciplinar nos domínios de autonomia curricular, cujo desenrolar é concomitante com a aquisição de aprendizagens essenciais transversais e aprendizagens essenciais por domínio das disciplinas envolvidas, bem como com o desenvolvimento de áreas de competências do perfil dos alunos à saída da escolaridade obrigatória. A título de meros exemplos, relacionados com a rede e bacia hidrográfica do Mondego, registe-se as problemáticas das invasões biológicas [e.g. Corbicula fluminea (O. F. Müller, 1774)], ou de espécies em risco [e.g. Potomida littoralis (Cuvier, 1798)] (Fig. 2). Figura 2 - A, B. Valas do rio Arunca (A) e detritos de limpeza de valas (B) onde é visível uma profusão de conchas de Corbicula fluminea e raras conchas de Potomida littoralis [Fonte: fotografia de R. Pimentel, 2020]. Um Éon de história dos Bivalvia: ideias sobre a sua origem, filogenia e importância paleontológica e educativa Os moluscos bivalves revelam uma extraordinária diversidade morfológica, partilhada por dezenas de milhar de espécies representativas da biosfera atual e do registo fóssil. As suas conchas, para além de apresentarem uma míriade de características com importância taxonómica (e.g. forma, simetria e ornamentação da concha, disposição e número de dentes e fossetas, dentículos, posição e tipo de ligamentos), permitem inferir carateres relacionados com os tecidos moles (e.g. marcas de inserção muscular e linha paleal) 3. Por estes factos, mesmo em atividades mais circunscritas, os bivalves revelam-se atores privilegiados de ações estratégicas, já que as suas conchas são propícias a atividades de carácter prático. São exemplos, o desenvovimento do domínio Sistemática dos seres vivos
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