Morphologic characterization of the ice wormMesenchytraeus solifugus

Abstract

Ice worms occupy a unique position in metazoan phylogeny in that they are the only known annelid that completes its life cycle in ice. The mechanism(s) associated with this adaptation are likely to occur at different levels, ranging from modification of their metabolism to changes in morphology. In this study, we examined specimens of Mesenchytraeus solifugus by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) in an effort to identify morphologic structures that may aid in its glacial habitation. We report that M. solifugus contains an elongated head pore at the tip of its prostomium, numerous sensory structures, and differentially oriented setae that curve abruptly at their distal end. J. Morphol. 246:192–197, 2000. © 2000 Wiley‐Liss, Inc.

Mesenchytraeus asymmetriauritus,a new enchytraeid (Annelida, Clitellata) from northeastern China

“…The stream-dwelling M. vshivkovae differs from M. asymmetriauritus by the lack of atrial glands, and by possessing at least 6 ampullar diverticula in each spermatheca (Timm 1994). The iceworm, M. solifugus, is distinctly separate from M. asymmetriauritus by its dark brown body color, obvious copulatory papillae, the abrupt distal setal curvature and the enlarged ventral chaetae in XI, the fewer spermathecal diverticula, more atrial glands, and one sperm sac extending to XX (Eisen 1905, Welch 1919, Goodman 1971, Shain et al 2000.…”

“…So far, only three congeners have been described with three or more diverticula, including the ice-worm M. solifugus (Emery, 1898) (possessing 3 diverticula), the Siberian and wetland M. mirabilis Eisen, 1878 (3-5), and the aquatic M. vshivkovae Timm, 1994 (at least 6) (Welch 1919, Eisen 1905, Cejka 1914, Goodman 1971, Timm 1994, Christensen & Dózsa-Farkas 1999, Shain et al 2000. All three species differ from M. asymmetriauritus by having an intraclitellar origin of dorsal vessel in common (Table 1).…”

“…Revision of Bryodrilus glandulosus (Dózsa-Farkas, 1990) and Mesenchytraeus kuehnelti Timm 1994Goodman 1971, Eisen 1905, Welch 1919, Shain et al 2000 This study…”

Mesenchytraeus asymmetriauritus,a new enchytraeid (Annelida, Clitellata) from northeastern China

“…The stream-dwelling M. vshivkovae differs from M. asymmetriauritus by the lack of atrial glands, and by possessing at least 6 ampullar diverticula in each spermatheca (Timm 1994). The iceworm, M. solifugus, is distinctly separate from M. asymmetriauritus by its dark brown body color, obvious copulatory papillae, the abrupt distal setal curvature and the enlarged ventral chaetae in XI, the fewer spermathecal diverticula, more atrial glands, and one sperm sac extending to XX (Eisen 1905, Welch 1919, Goodman 1971, Shain et al 2000.…”

“…So far, only three congeners have been described with three or more diverticula, including the ice-worm M. solifugus (Emery, 1898) (possessing 3 diverticula), the Siberian and wetland M. mirabilis Eisen, 1878 (3-5), and the aquatic M. vshivkovae Timm, 1994 (at least 6) (Welch 1919, Eisen 1905, Cejka 1914, Goodman 1971, Timm 1994, Christensen & Dózsa-Farkas 1999, Shain et al 2000. All three species differ from M. asymmetriauritus by having an intraclitellar origin of dorsal vessel in common (Table 1).…”

“…Revision of Bryodrilus glandulosus (Dózsa-Farkas, 1990) and Mesenchytraeus kuehnelti Timm 1994Goodman 1971, Eisen 1905, Welch 1919, Shain et al 2000 This study…”

Applicability of cryoconite consortia of microorganisms and glacier-dwelling animals in astrobiological studies

“… Some of organisms on Arctic and Alpine glaciers have dark pigment -the protection against UV radiation (e.g., Shain et al 2000;Greven et al 2005;Remias et al 2005).  Physical, chemical and biological conditions in ice-covered cryoconite holes form a unique combination among the surface waters on Earth and ice covered biotic and abiotic interactions may form astrobiological analogues (e.g., Vincent and Howard-Williams 2000; Tranter et al 2004;Doran et al 2010).…”

Divergence of the F1-ATP Synthase Complex in the Ice Worm, Mesenchytraeus solifugus (Annelida, Clitellata, Enchytraeidae)

“…Mesenchytraeus solifugus specimens were collected from Byron Glacier, Alaska and maintained as described in Shain et al (2000). Enchytraeus albidus, Enchytraeus buchholzi and Lumbriculus variegatus were purchased from the Bug Farm (San Rafael, CA), and although their species designation was not confirmed, their external features (e.g., size, coloration, setal morphology) were consistent with previous descriptions (e.g., Brinkhurst & Jamieson, 1971).…”

Mesenchytraeus asymmetriauritus,a new enchytraeid (Annelida, Clitellata) from northeastern China

“…The stream-dwelling M. vshivkovae differs from M. asymmetriauritus by the lack of atrial glands, and by possessing at least 6 ampullar diverticula in each spermatheca (Timm 1994). The iceworm, M. solifugus, is distinctly separate from M. asymmetriauritus by its dark brown body color, obvious copulatory papillae, the abrupt distal setal curvature and the enlarged ventral chaetae in XI, the fewer spermathecal diverticula, more atrial glands, and one sperm sac extending to XX (Eisen 1905, Welch 1919, Goodman 1971, Shain et al 2000.…”

“…So far, only three congeners have been described with three or more diverticula, including the ice-worm M. solifugus (Emery, 1898) (possessing 3 diverticula), the Siberian and wetland M. mirabilis Eisen, 1878 (3-5), and the aquatic M. vshivkovae Timm, 1994 (at least 6) (Welch 1919, Eisen 1905, Cejka 1914, Goodman 1971, Timm 1994, Christensen & Dózsa-Farkas 1999, Shain et al 2000. All three species differ from M. asymmetriauritus by having an intraclitellar origin of dorsal vessel in common (Table 1).…”

“…Revision of Bryodrilus glandulosus (Dózsa-Farkas, 1990) and Mesenchytraeus kuehnelti Timm 1994Goodman 1971, Eisen 1905, Welch 1919, Shain et al 2000 This study…”

Applicability of cryoconite consortia of microorganisms and glacier-dwelling animals in astrobiological studies

“… Some of organisms on Arctic and Alpine glaciers have dark pigment -the protection against UV radiation (e.g., Shain et al 2000;Greven et al 2005;Remias et al 2005).  Physical, chemical and biological conditions in ice-covered cryoconite holes form a unique combination among the surface waters on Earth and ice covered biotic and abiotic interactions may form astrobiological analogues (e.g., Vincent and Howard-Williams 2000; Tranter et al 2004;Doran et al 2010).…”

Divergence of the F1-ATP Synthase Complex in the Ice Worm, Mesenchytraeus solifugus (Annelida, Clitellata, Enchytraeidae)

“…Mesenchytraeus solifugus specimens were collected from Byron Glacier, Alaska and maintained as described in Shain et al (2000). Enchytraeus albidus, Enchytraeus buchholzi and Lumbriculus variegatus were purchased from the Bug Farm (San Rafael, CA), and although their species designation was not confirmed, their external features (e.g., size, coloration, setal morphology) were consistent with previous descriptions (e.g., Brinkhurst & Jamieson, 1971).…”

Mesenchytraeus asymmetriauritus,a new enchytraeid (Annelida, Clitellata) from northeastern China

“…The stream-dwelling M. vshivkovae differs from M. asymmetriauritus by the lack of atrial glands, and by possessing at least 6 ampullar diverticula in each spermatheca (Timm 1994). The iceworm, M. solifugus, is distinctly separate from M. asymmetriauritus by its dark brown body color, obvious copulatory papillae, the abrupt distal setal curvature and the enlarged ventral chaetae in XI, the fewer spermathecal diverticula, more atrial glands, and one sperm sac extending to XX (Eisen 1905, Welch 1919, Goodman 1971, Shain et al 2000.…”

“…So far, only three congeners have been described with three or more diverticula, including the ice-worm M. solifugus (Emery, 1898) (possessing 3 diverticula), the Siberian and wetland M. mirabilis Eisen, 1878 (3-5), and the aquatic M. vshivkovae Timm, 1994 (at least 6) (Welch 1919, Eisen 1905, Cejka 1914, Goodman 1971, Timm 1994, Christensen & Dózsa-Farkas 1999, Shain et al 2000. All three species differ from M. asymmetriauritus by having an intraclitellar origin of dorsal vessel in common (Table 1).…”

“…Revision of Bryodrilus glandulosus (Dózsa-Farkas, 1990) and Mesenchytraeus kuehnelti Timm 1994Goodman 1971, Eisen 1905, Welch 1919, Shain et al 2000 This study…”

Applicability of cryoconite consortia of microorganisms and glacier-dwelling animals in astrobiological studies

“… Some of organisms on Arctic and Alpine glaciers have dark pigment -the protection against UV radiation (e.g., Shain et al 2000;Greven et al 2005;Remias et al 2005).  Physical, chemical and biological conditions in ice-covered cryoconite holes form a unique combination among the surface waters on Earth and ice covered biotic and abiotic interactions may form astrobiological analogues (e.g., Vincent and Howard-Williams 2000; Tranter et al 2004;Doran et al 2010).…”

Divergence of the F1-ATP Synthase Complex in the Ice Worm, Mesenchytraeus solifugus (Annelida, Clitellata, Enchytraeidae)

“…Mesenchytraeus solifugus specimens were collected from Byron Glacier, Alaska and maintained as described in Shain et al (2000). Enchytraeus albidus, Enchytraeus buchholzi and Lumbriculus variegatus were purchased from the Bug Farm (San Rafael, CA), and although their species designation was not confirmed, their external features (e.g., size, coloration, setal morphology) were consistent with previous descriptions (e.g., Brinkhurst & Jamieson, 1971).…”