Population biology of two pycnogonid species (Amnotheidae) at hydrothermal vents in the northeast Pacific
Brescia, L.A.; Tunnicliffe, V. (1998). Population biology of two pycnogonid species (Amnotheidae) at hydrothermal vents in the northeast Pacific. Cah. Biol. Mar. 39(3-4): 233-236. https://dx.doi.org/10.21411/CBM.A.8D40420F
In: Cahiers de Biologie Marine. Station Biologique de Roscoff: Paris. ISSN 0007-9723; e-ISSN 2262-3094
Also appears in:
(1998). Proceedings of the First International Symposium on Deep-Sea Hydrothermal Vent Biology: Funchal, Madeira, Portugal 20-24 October 1997. Cahiers de Biologie Marine, 39(3-4). Station Biologique de Roscoff: Roscoff. 219-392 pp., more
Little is known about the biology of the less conspicuous hydrothermal vent species. Studies on the evolution and ecology of this habitat remain dependent on understanding the basic biology of important component organisms. That requirement fuelled this study on pycnogonids or "sea spiders". These animals are often abundant in vent collections from the northeast Pacific and observers have noted them in high densities near high temperature vents. Class Pycnogonida is a marine arthropod group found throughout the ocean. Although they are chelicerates, they only superficially resemble true spiders of the order Arancae. They typically have four pairs of multiarticulate le-s but some genera have up to six pairs. Their distinguishing features include the much reduced abdomen and a large proboscis used for feeding. During mating, the eggs are transferred to the male who carries the eggs in masses attached to ovigers held under the segmented trunk. The protonymphon larvae is often parasitic on invertebrates (Arnaud & Bamber, 1987). Vent pycnogonids are known from the northeast Pacific, western Pacific and Atlantic vents. Child (1987) describes the two species studied here: Ammothea verenae Child, 1987 and Sericosura venticola Child, 1987 of the family Ammotheidae. Both species are eyeless and similar in appearance. They are distinguished most readily by the number of palp segments. There is nothing reported about the population structure of these sea spiders nor how they fit into the food web of the hot vent habitat. "Another question begging an answer, in relation to hydrothermal vent-associated pycnogonids, concerns the nature of food available to them." (Child, 1987, p. 900). Most pycnogonids, are fluid feeders on sessile invertebrates and have intracellular digestion. The objective of this study was to determine i) if the niches of the two species can be readily identified, ii) if populations at the same site show stable structure, and iii) if there are unusual features of reproduction or feeding that can he deduced from collected specimens.
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