Abstract
IN a previous article attention was called to some of the more remarkable of the deep-sea fishes taken during the recent cruise of the French frigate the Talisman: not less interesting were the numerous forms of Crustacea dredged during the same cruise, a fine collection of which were also on view at the Jardin des Plantes, Paris, as part of the spoils brought home after the voyage. From a survey of the specimens it is evident that these Crustacea are to be found at all depths of the ocean: some pass their lives floating on its surface, feeding thereon or amid the acres of Sargassum weed; while others live at depths of from 4000 to 5000 metres. The so-called swimming crabs which form a section of the Brachyura would seem to be extremely rare at great depths. Certain species taken during the Talisman's cruise are remarkable for their very extensive geographical distribution; thus, species of Batynectes which were found at depths of from 450 to 950 metres off the coasts of Morocco and about the. Caps Verd Islands, seemed very closely related to the swimming crabs (Portunus) of our own seas, and again to be very nearly connected to species of the same genus collected at the Antilles, in the Mediterranean, and in the Arctic Ocean. Another section of the Brachyura, with sharp triangular bodies (Oxyr-rhyncha), contains species which are to be met with at much greater depths; thus Lispognatus thompsoni (A. M. Edw.) was dredged off the coasts of Morocco from depths of between 600 and 1500 metres, and Scyramathia carpenteri was taken at the same place from a depth of 1200 metres. The former of these species has been found in the North Sea, and the latter has been taken off the north of Scotland and in the Mediterranean. The Crustacea intermediate by their forms between the Brachyura and the Macrura were found in abundance at very great depths, and the forms found seemed in great measure to belong to “transition” forms; so one was often surprised to find a form, which taken by itself appeared abundantly distinct, quite connected with others by numerous intermediary forms. Thus species of Ethusa, Dorippe, Homola, and Dromia seem to present such numerous shades of gradation as to perplex one completely in the difficult task of classifying these genera. Some of these forms are also very remarkable for their geographical distribution: a species of Dicranomia, described by Milne-Edwards from the Antilles, was found off Morocco, and Homola cuvierii, up to this thought to be peculiar to the Mediterranean, was found at the Azores and the Canaries. But the most remarkable instance of the geographical extension of which some genera are capable is furnished by some species of the family Lithodina. These Crustacea to this have been known as inhabitants of the Arctic and Antarctic region?, living in the littoral zone, but now they have been found under the tropics; the only difference being that in this latter locality they have contrived to find congenial conditions of life by abandoning their shallow-water life and betaking themselves to the cool depths of over 1000 metres. A fact like this is not without its interest, inasmuch as it shows how some forms can spread themselves from the frozen seas of the north to the seas of the tropics, and so from the region of one Pole to the other; altering their conditions of life as necessity demanded, and resuming their old habits when the opportunity to do so again occurred.
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The Deep-Sea Dredgings of the “Talisman”—Crustacea . Nature 29, 531–533 (1884). https://doi.org/10.1038/029531b0
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DOI: https://doi.org/10.1038/029531b0