Hemoglobin‐containing cells of Neodasys (Gastrotricha, Chaetonotida). I. Morphology and ultrastructure

Abstract

The overall anatomy of Neodasys as well as data for hemoglobin-containing cells are described. Hemoglobin-containing cells are shown to be mesodermal specializations constituting approximately 14% of the animal's total body volume (4.87 ± 10 μl). These globular cells (10-14 μm) are situated in two longitudinal rows, each dorsolateral to the straight gut. Branches from the cells enwrap perikarya of muscle and nerve cells whose mitochondria are found just below their respective plasmalemmata in intimate association with the hemoglobin-containing cells. The ground substance of the cytoplasm and nucleoplasm of these nearly organelle-free cells is extremely electron-dense and is presumed to represent the hemoglobin molecules. Locomotion analyses indicate that the cells can undergo a threefold change in linear dimension in 0.25 seconds, raising the possibility of convective mixing in these cells. Structural and ultrastructural comparisons with similar cells in adults of other species of Gastrotricha indicate that the hemoglobin-containing cells of Neodasys may be homologous to the socalled Y cells of other species, some of which contain myofilaments. A muscle-cell origin is considered for the evolution of hemoglobin-containing cells of Neodasys.

Marine gastrotrichs from the Tuscan achipelago (Tyrrhenian Sea): II. Chaetonotida, with description of three new species

“…As with other specimens collected from Italian localities and along the coasts of Kenya, those from Tuscany showed a series of ventral scales posterior to the anus, quite similar to those described by Ruppert (1979) for X. carolinensis. This finding and the general overlap of morphometric parameters have led us to consider X. carolinensis synonymous with X. intermedia.…”

“…Remarks -The morphometric parameters of the specimens from Elba fall within the range of variability for the species, more closely resembling those reported by Ruppert (1979).…”

“…CAPRAIA: Cala délia Mortola, IX.1990, SL, 1 ind; Punta della Civitata, SL, 1 ind. (Mock, 1979); coasts of Scotland (Hummon, 1976); Atlan-, tic coasts of the USA (Hummon, 1974b, c,'l975;Ruppert, 1979); Japan (Sudzuki, 1977). In the Mediterranean Sea, it is known from Greece (Hummon & Roidou, in press), and in Italy from Tuscany, Campania, Apulia and the Marches (Luporini etal., 1971(Luporini etal., , 1973Renaud-Mornant, 1968;Balsamo, Hummon & Todaro, unpubl.…”

“…Geographic distribution and ecology -North Sea (Mock, 1979); English Channel and Atlantic coasts of France (Kisielewski, 1988); western Scotland (Hummon, 1976) and Atlantic coasts of the USA (Hummon, 1974b(Hummon, , 1975Ruppert 1979). In the Mediterranean Sea, it is present on the coast of Marseilles (Swedmark, 1956), Greece (Hummon & Roidou, in press) and along the Tyrrhenian, Ionian and southern Adriatic Seas (Wilke, 1954;Luporini et al, 1973;Todaro & Balsamo, in press;Balsamo, Hummon & Todaro, unpubl.…”

“…Geographic distribution and ecology -Baltic Sea (Remane, 1934), English Channel (d'Hondt, 1968a, North Wales (Boaden, 1963a), Atlantic coasts of France (Ruppert, 1979), coasts of Somalia (Valbonesi & Luporini, 1987), India (Chandrasekhara Rao & Ganapati, 1967). In the Mediterranean Sea, it is present in Italy along the coasts of Apulia and Tuscany (De Zio & Grimaldi, 1964;Luporini et al, 1971).…”