Abstract.Seven harpacticoid species were found to be associated with sea ice collected during 5 Antarctic cruises of the RV Polarstern. Their distribution within the fast ice and pack ice zones of the Weddell Sea is presented. Whereas some individuals probably become entrapped into the ice only accidentally, at least 4 species arc genuinely sympagic. These have evolved remarkable adaptations, as evidenced by field and laboratory studies ofDresclieriella glacialis, which is by far the most abundant. Such adaptations include: the ability to penetrate deep into ice; a comparatively high salinity tolerance allowing it to endure large salinity fluctuations associated with ice crystal formation and melting; good swimming ability, necessary both for horizontal dispersal and for a planktonic intermezzo after annual melting of the sea ice.D. glacialisis the first polar non‐vertebrate mctazoan to be cultivated through its entire life cycle. Its life history suggests an r‐stratcgy; this would be the first indication of such a trait in the polar environment. A new species ofDrescheriella, on the other hand, exhibits resting stages (C IV‐V) known to date only forCalanoidubut not reported forHarpacti
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