The Beagle years 18316

CD's plan, when he embarked on the Beagle, was to collect enough material and observations to write, on his return, an account similar to von Humboldt's Voyage aux regions equinoxiales du Nouveau Continent (1805-39), which he greatly admired. Moreover, as ichthyology, in the early nineteenth century, was completely dominated by French taxonomists, as illustrated by the *HistoireNaturelledesPoissons, CD also planned to collect fish specimens that would prove to be new species; the more the better. Thus, he concentrated his fish sampling effort in areas not previously, or little, explored by French vessels. Hence the thoroughness of his collecting work in Southern South America, and his more limited samples from the Indo-Pacific.

CD's conservative sampling strategy, dictated in part by the difficulties in preserving and shipping specimens back to England (with Henslow at the receiving end), did pay off, as illustrated by a letter of October 1839 to Jenyns, in which he congratulates himself: I am astonished & glad to hear how many new things you seem to have found - four new genera is something. There would have been more, had not a part ofthe *collection rotted away.

One important reason why the strategy worked is that Jenyns did a very competent job of describing CD's fishes, successfully navigating the waters between the Scylla of lumping distinct species, and the Charybdis of splitting mere variations into named species. (*FishBase was the main source of updated *names, i.e. the main tool I used to establish the correspondence between his species names and those now considered valid; see also the Index to the Fishes).

CD clearly believed, long before he conceived *sexual selection (through which he explained sex-related differences in the *colours of fish and other animals), that the colours of animals matter, and the descriptions of the live colours of most of his specimens, e.g. in *Fish in Spirits of Wine, attest to this. Moreover, he did not let his imagination colour his descriptions, basing them, rather, on the colour-coded charts in a book he took with him for that very purpose (Syme 1821). Thus, we can attribute to CD the first rigorous treatment of colours in biology in general, and in ichthyology in particular.

This attention to details which other naturalists may have overlooked is also evident from other aspects of his field work, for example, by his collection in the *Cape Verde, *Falkland or *Galapagos Islands. Notably, this involved performing simple - we might call them Baconian - *experiments, on the behaviour, *ecology, or physiology of various animals, including fishes. This involved, for example, cutting open a marine *iguana in the Galapagos (try that now!) to settle a longstanding dispute on whether they feed on underwater vegetation or on fish, dropping marine fishes into freshwater to see if they would adapt, and more.

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