Belongs within: Aoridae.
Life in a muddy tube
Published 27 February 2026
For marine animals, there’s a lot to be said for living buried in the sediment. The environment is stable, protected, and well-supplied with organic food sources. But this lifestyle also brings challenges, not least of which is avoiding getting choked by the sediment itself. So infaunal animals may construct themselves discrete domiciles, such as those made by species of the amphipod genus Grandidierella.
Grandidierella is a pantropical and subtropical genus of over 25 species, comprising slender amphipods with subcylindrical bodies and long limbs. The first gnathopod (i.e. the first prominent leg) is more or less chelate with the last segment opposing the second-to-last. In males, the first gnathopod is particularly large, with an enlarged tooth on the fifth segment forming a sort of thumb (Barnard 1969). Males of at least one species, G. japonica, have been observed rubbing a series of grooves on article 5 of the first gnathopod along the edge of article 2, and it seems that this functions as a stridulatory organ (Chapman & Dorman 1975). Historically, Grandidierella was also defined by a long basal segment on the mandibular palp, distinguishing it from genus Neomicrodeutopus in which this segment was short, but this feature is no longer regarded as significant and the two genera are treated as synonyms.
Grandidierella species are found in littoral habitats, particularly in brackish water. They are presumably detritivores, and build themselves U-shaped tubes in muddy substrates. Often, a male and female will be found living in a single tube. Males will also wander about on the surface of the sediment at low tide. The species G. japonica, a native of the northwest Pacific, has become widespread outside its native range on the North American west coast and in Europe. It is believed to have been passively carried to its new ranges by humans, probably as hitch-hikers on oysters being transported for aquaculture. And then they set to work, building their tubes on a whole new continent.
Systematics of Grandidierella
Grandidierella Coutière 1904S86 [incl. Bigrandidierella Karaman 1985BK91, Neomicrodeutopus Schellenberg 1925M81, B69]
|--*G. mahafalensis Coutière 1904B69
|--G. africana Schellenberg 1936BK91
|--G. bispinosa Schellenberg 1938BK91
|--G. bonnieroides Stephensen 1947BK91
|--G. cabindae Schellenberg 1925BK91 [=*Neomicrodeutopus cabindaeB69]
|--G. chelata Barnard 1951BK91
|--G. dentimera Myers 1970BK91
|--G. elongata (Chevreux 1926) [=Neomicrodeutopus elongata]BK91
|--G. exilis Myers 1981BK91
|--G. gilesi Chilton 1921BK91
|--G. gravipes Barnard 1935BK91
|--G. grossimana Ledoyer 1967BK91
|--G. indentata Ledoyer 1979BK91
|--G. insulae Myers 1971BK91
|--G. japonica Stephensen 1938BK91
|--G. koa Barnard 1977BK91
|--G. lignorum Barnard 1935BK91
|--G. longidactyla Ledoyer 1982BK91
|--G. lutosa Barnard 1952BK91
|--G. macronyx Barnard 1935BK91
|--G. makena Barnard 1970 [incl. G. bonnieri Stebbing 1908]BK91
|--‘Microdeutopus’ megnae Giles 1888 [=*Bigrandidierella megnae]BK91
|--G. nottoni Shoemaker 1935BK91
|--G. nyala Griffiths 1974BK91
|--G. palama Barnard 1977BK91
|--G. perlata Schellenberg 1938BK91
|--G. propodentata Moore 1986BK91
|--G. robusta Ledoyer 1982BK91
|--G. spinicoxa Myers 1972BK91
|--G. teres Myers 1981BK91
`--G. vietnamica Dang 1968BK91
*Type species of generic name indicated
References
[B69] Barnard, J. L. 1969. The families and genera of marine gammaridean Amphipoda. United States National Museum Bulletin 271: i–vi, 1–535.
[BK91] Barnard, J. L., & G. S. Karaman. 1991. The families and genera of marine gammaridean Amphipoda (except marine gammaroids). Part 1. Records of the Australian Museum Supplement 13 (1): 1–417.
Chapman, J. W., & J. A. Dorman. 1975. Diagnosis, systematics, and notes on Grandidierella japonica (Amphipoda: Gammaridea) and its introduction to the Pacific coast of the United States. Bulletin of the Southern California Academy of Sciences 74: 104–108.
[M81] Myers, A. A. 1981. Amphipod Crustacea I. Family Aoridae. Memoirs of the Hourglass Cruises 5 (5): 1–75.
[S86] Stock, J. H. 1986. Order Amphipoda: an introduction. In: Botosaneanu, L. (ed.) Stygofauna Mundi: A Faunistic, Distributional, and Ecological Synthesis of the World Fauna inhabiting Subterranean Waters (including the Marine Interstitial) pp. 494–496. E. J. Brill/Dr W. Backhuys: Leiden.