Review Article |
Corresponding author: Maxim V. Vinarski ( radix.vinarski@gmail.com ) Academic editor: Matthias Glaubrecht
© 2014 Maxim V. Vinarski.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Vinarski M (2014) The birth of malacology. When and how? Zoosystematics and Evolution 90(1): 1-5. https://doi.org/10.3897/zse.90.7008
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In 1795, Georges Cuvier proposed a new classification of invertebrate animals based on anatomical data. He created a new concept of mollusks as representatives of a unique type of morphological organization of animals. Before Cuvier, the name “mollusks” was used only for cephalopods without external shells and slugs, whereas all shelled mollusks were placed in another taxon, Testacea. The Cuvier’s works (
Mollusks, Mollusca , Cuvier, Ducrotay de Blainville, anatomy, taxonomy, history of science, Rafinesque
About two hundred years ago no students of mollusks might identify himself or herself as a “malacologist”. The very term “malacology” did not exist at the time, and the study of snails, clams and other testaceous animals, including barnacles and even foraminiferans, had been known under the name “conchology” or, more rarely, “testaceology” (
When, why, and how did the classical branch of natural science named “conchology” transform into a new scientific discipline known as “malacology”?
This observation, however, is not completely true at least due to the fact that the explicit distinction between conchology and malacology was proposed as early as in 1825 by a French zoologist Ducrotay de
Aristotle was surely the first man of science to study mollusks seriously. In his famous “Historia animalium”, Aristotle gave a collection of his own thorough observations on external morphology, anatomy, reproduction, ecology and behavior of many soft-bodied animals that are classified today within the phylum Mollusca. Aristotle created the first universal classification of animals through his distinction between blooded (vertebrates) and bloodless (invertebrates) animals (
Order Intestina – genus Teredo along with such dissimilar creatures as Lumbricus (earthworm), Hirudo (leech), Ascaris (helminthes), and Myxine (hagfish).
Order Mollusca – essentially a direct descendant of Aristotle’s Malakia. The genuine molluscan genera (Limax, Doris, Sepia and others) were placed here, accompanied by such genera of soft-bodied aquatic animals from other invertebrate phyla, such as Medusa, Asterias (starfish), Nereis, and Holothuria.
Order Testacea – a species rich taxon including clams, snails, chitons as well as crustaceans (Lepas), annelids (Serpula) and scaphopods (Dentalium).
This is nothing but a reiteration of the classic system of Aristotle albeit more precisely developed. The presence or absence of the shell was the most important trait for classification, which is why Linnaeus distributed cephalopods between two orders. The shelled genera Argonauta and Nautilus were placed within Testacea, whereas the rest fell into the order Mollusca. Linnaeus’ system of testaceous “vermes” was not strictly conchological, since he included some external characters of the mollusks’ soft bodies in the diagnoses of some higher taxa and even genera. For example,
But the internal anatomy as a tool for classification of invertebrates was commonly ignored by taxonomists of Linnaeus’ time. Many naturalists of the 18th and even 19th centuries consciously rejected anatomical data in their taxonomic work (
Some conchologists declared that the system of mollusks based on anatomy is more scientific that the shell-based one (
The end of this anatomical ignorance is often thought to be inspired by Cuvier’s extensive studies on the comparative anatomy of animals.
Contrary to
A more detailed version of the system was presented in the next important work of Cuvier, «Tableau élémentaire de l’histoire naturelle des animaux» (
The next important step of development of the system of mollusks was in 1812, when Cuvier explicitly expressed his great idea that all animals can be distributed among four large branches (embranchements) corresponding to four basic morphological groundplans (
Cuvier published the last version of the system of Mollusca based on the type concept in 1817, and, somewhat changed, it was proclaimed again in 1830 (
Group | Classes | Orders |
---|---|---|
Mollusques | Céphalopodes | none |
Ptéropodes | none | |
Gastéropodes | Nudibranches, Inferobranches, Tectibranches, Pulmonés, Pectinibranches, Scutibranches, Cyclobranches | |
Acéphales | Acephales testacés (= Bivalvia), Acephalés sans coquilles (= Tunicata) | |
Brachiopodes | none | |
Cirrhopodes (= Cirripedia) | none |
In 1825, Ducrotay de Blainville proposed a new term, “malacozoaires” (Malacozoa), to designate all these invertebrate animals with soft coverings that corresponded to the Cuvier’s diagnosis of “les mollusques”. Another term, malacology, was invented for designation of a branch of science devoted to study of malacozoaires. De Blainville wrote: “A branch of science devoted to this part of zoology [i.e. study of Malacozoa] still lacks a name; since Molluscologie cannot be used as being a hybrid [word], and since Conchyliologie is hardly better as it deals with only coverings of these animals, we propose here [a term] Malacozoologie, or, in abbreviated form, Malacologie…” (
Blainville clearly considered his term “Malacologie” as being entirely new. Most probably, he was not aware that nine years earlier, in 1814, the same word was introduced by Rafinesque in a rather obscure pamphlet published in Palermo (Italy) and entitled “Principes fondamentaux de somiologie ou les loix de la nomenclature et de la classification de l’empire organique” (see
Rafinesque attempted to give a special name for each branch of zoology devoted to study of a particular taxon. Some of his terms sound highly exotic. For example, he introduced the term “plaxologie” for the studies of crustaceans, the term “anostologie” for a field of zoology devoted to all invertebrates and so on. “Malacologie” was proposed by Rafinesque to label the study of Malacosia, or mollusques (
Cuvier revolutionized invertebrate systematics through his pioneering studies in comparative anatomy, and should be considered the genuine “father of malacology.” The conceptual shift from conchology to malacology took place between 1795 and 1825 when Cuvier developed his new and revolutionary ideas on systematization of invertebrates. This conceptual transition was concerned with appearance of three new concepts not characteristic for conchology in its classical sense:
Mollusks represent a unique plan of organization of animals embracing both shelled and non-shelled species of animals with soft coverings and uniform internal structures. The shell as such is not essential for definition of Mollusca.
The shell is only a part of the whole body of a molluscous animal. Shell characters of mollusks are correlated with the structure of their internals that allows conchological traits to be useful for diagnostics and delineation of lower taxa, but shells have only secondary significance for arrangement of classes and order of Mollusca.
Shells are worth examining as objects of nature, but conchology as such constitutes merely a part of a broader branch of zoology that deserves a special name for its designation.
Zoologists in 1800-1810s did not express these three concepts explicitly, but all of them were implicitly contained in works of Cuvier and his associates. Rafinesque’s and Blainville’s formal establishment of malacology addressed this state of affairs and marked the birth of a new scientific discipline by a proper term. Thus, malacology was born nameless until Rafinesque and Blainville’s time. This is not a rare case in the history of science. For example, Aristotle, the “father of zoology”, contributed very much to biology without knowing the very word “biology”, which did not appear until 1802. Similarly, Cuvier and Lamarck worked as true malacologists even before the word “malacology” was introduced to the dictionaries by Rafinesque and their compatriot Blainville.
Thus, the birth of malacology was not a sort of “saltation”. Most probably, it was, in reality, a slow “tectonic” shift in zoological thinking that took at least three decades. This process ran parallel with a much larger one, the gradual transformation of “natural history” flourished in the Age of Reason to modern biology (
For those, who still seek for the “exact” date of birthday of malacology, I propose 10 May of 1795 (= 21 floréal an III), a day when Cuvier delivered his lecture on the arrangement of “vermes”, including mollusks, before the Society of Natural History [see
I am grateful to Dr. Alan Kabat and an anonymous reviewer for theirs comments and polishing the English. I received a partial financial support for this study from the Russian Foundation for Basic Research (projects № 12-04-31564_mol_a; 12-04-98056-р_sibir_а) and the Russian Ministry of Education and Science (project № 4.2326.2011).