Author: Ibon Cancio, UPV/EHU Associated Professor in Cell Biology; researcher in the ‘Cell Biology & Environmental Toxicology’ (CBET) research group of the Plentzia Marine Station (PiE-UPV/EHU); Spanish scientific representative in the EMBRC Committee of Nodes
Charles Darwin, the scientist having made the most important contribution to biological knowledge, was not only focused on marine organisms or biology itself, but he was ALSO a very relevant marine biologist.
The young Darwin, at age 16, initiated his studies in medicine in Edinburgh. He hated ‘academic’ medicine, and he disliked his medicine teachers, but he loved natural history. Soon he found a mentor in Robert Edmond Grant, a zoology professor who studied sponges and created the group ‘Porifera’ for them. It was a time where the distinction between animals and plants was controversial for some groups of invertebrate animals, for instance sponges themselves or bryozoans (moss animals mostly forming sedentary colonies).
Darwin eagerly explored the intertidal zone in the Firth of Forth and accompanied fishermen during their trawls at sea. He presented the first results of his observations to the Plinian Society (ie natural history society of students in the University of Edinburgh) on the bryozoan Flustra foliacea and the marine leech Pontobdella muricata at the age of 18. He had observed for example that the larvae of the bryozoan use cilia for locomotion. Darwin would ultimately become disappointed by his mentor (Grant), but not before the latter gave him a passion for marine organism research and he became interested in the concept of ‘species transmutation’.
Young Darwin’s big opportunity came when he embarked on the ‘HMS-Beagle’ (1831-1836) as a self-sustained, gentleman naturalist. In a trip of discovery, the most famous one in the history of biology, he collected samples that he sent periodically to Great Britain from harbours where the expedition took shelter and that he would thoroughly classify upon his return. He came up with a theory, published in 1842, for the way in which coral reefs are formed. Inspired by his field observations, he used a biological and ecological understanding to explain a geological process that was soon accepted by the most eminent geologist of the moment (of all moments): Sir Charles Lyell.
Very late after the Beagle expedition, Darwin would construct the cathedral that houses all biological knowledge: ‘The Origin of Species’. It would be an ‘earthquake’ for the academic establishment and the scientific and religious status quo. But this would not occur until 1859. What happened in between? Marine biology happened, marine biology of the best quality. By all means, inspirational for the genius and his theory. The young naturalist needed to make a name for himself among the British scientific community proving that he was a reliable scientist. Darwin had to earn his stripes! To achieve this, he devoted his days to a monograph on cirripeds (barnacles), only recently classified as crustaceans instead of molluscs, which was published in four books between 1846 and 1854. As Joseph Hooker, Darwin´s best friend said, ‘No one has hardly a right to examine the question of species who has not minutely described many’.
In his decision to dig into the biology of barnacles, an important role was played by a barnacle that he found in the southern coast of Chile during the Beagle expedition. This organism remained unclassified. Meanwhile, it received a nickname, ‘Mr Arthrobalanus’. The barnacles needed somebody who would analyse them systematically. Darwin's monographic work would be monumental and global from any perspective and it earned him the Medal of the Royal Society of Great Britain in 1853. In his work, he used his microscope and an important piece of infrastructure, the British Royal Mail. He would receive at home specimens from museums, private collections, and amateur naturalists that collected live and fossil specimens from seashores worldwide. All species of cirripeds were considered hermaphrodites, with testis and ovary together. However, in the case of ‘Mr Arthrobalanus’, similar to barnacles in other few genera, Darwin was facing a species in the midst of a transition towards separated sexes. Some species presented dwarf males surviving on hermaphroditic individuals, while in others both sexes were completely separated, with dwarf parasitic males living on giant females. Darwin, confronted with such transitional species, a phenomenal manifestation of evolution, probably experienced a ‘Eureka’ moment, which was important in the materialisation of his ‘Origin of Species’. Marine invertebrates in their simplicity allow the investigation of complex biological traits better than in complex animal forms and are thus important for understanding natural history.
Researchers studying such diversity of marine invertebrates strongly aligned with the evolution theory after its publication. A Prussian zoologist, Anton Dohrn (1840-1909), was convinced that scientists needed research stations located on the coast to allow investigations on marine organisms and their biodiversity. He would create a marine station with a mission to find evidence of the theory of evolution in the Gulf of Naples (that marine station is Stazione Zoologica Anton Dohrn (SZN), EMBRC Italy’s lead partner). Dohrn and Darwin became pen-pals and exchanged many letters. In one of them, Darwin congratulated Dohrn on the achievement of the creation of his Naples marine station and contributed with money for the project and with books for the station’s outstanding library. We can say, rephrasing Darwin: ‘From so simple a beginning endless forms (of marine stations) most beautiful and most wonderful have been, and are being, evolved’. The rest is history in research in marine biological stations!