Life‐history traits of the bisexual tardigrades Paramacrobiotus tonollii and Macrobiotus sapiens

Abstract

The present work is the first one presenting life-history information of bisexual tardigrades under laboratory conditions. Two bisexual tardigrade strains (Paramacrobiotus tonollii and Macrobiotus sapiens) were examined analysing the following life-history traits: active life span, body lengths, age at first oviposition, egg-laying intervals, clutch size, hatching time and hatching percentages. Comparing parthenogenetic and bisexual tardigrades, our results demonstrate that life-history traits did not correlate to a mode of reproduction but rather vary in between the different species. Differences were observed for embryonic development (P. tonollii: 16 days; M. sapiens: 12 days), for body lengths (P. tonollii larger than M. sapiens) and for a longer life span of M. sapiens (about 83 days).

Reproductive traits of Macrobiotus hufelandi during a long-term field study with notes on Paramacrobiotus richtersi and Diphascon pingue (Eutardigrada)

“…Data may vary depending on temperature and species. In cultures developmental and generation times are in most cases considerably shorter than those calculated by us; in M. hufelandi egg development takes 10 days and embryonic development 26-31 days (Baumann, 1970;Altiero and Rebecchi, 2001;Suzuki, 2003;Hohberg, 2006;Horikawa et al, 2008;Lemloh et al, 2011). Extended times of development may be explained among others by the more or less periodic dehydration of the moss (Marcus, 1929), in which development stops or is considerably slowed down, or the absence of favourable temperatures combined with specific humidities.…”

“…Authors could not determine a distinct pattern in abundance, but found the largest individuals (with high reproductive rates) in the winter and early spring and the smallest in summer. Usually, tardigrades were measured either in asphyxia (Schütz, 1987) or mounted on microscope slides using various embedding media (Morgan, 1977;Kathman and Nelson, 1987) or during walking using time lapse movies (Lemloh et al, 2011) or details were not given (Hohberg, 2006). When measuring specimens after gently pressing the coverslip, we accept some inaccuracies, but our measurements are in the range known for the three species, and we could detect size differences.…”

Distribution and diversity of Tardigrada along altitudinal gradients in the Hornsund, Spitsbergen (Arctic)

“…In fact, a majority of limno-terrestrial tardigrade species are thought to be parthenogenetic (Bertolani 2001). Moreover, the type of reproduction may vary not only between different tardigrade species but also between populations of the same species (Nelson et al 2010;Lemloh et al 2011).…”

The genus Milnesium Doyère, 1840 (Tardigrada) in South America with descriptions of two new species from Argentina and discussion of the feeding behaviour in the family Milnesiidae

“…in the carnivorous Paramacrobiotus richtersi (Murray, 1911), b) predator-prey interactions (P. richtersi vs. nematodes), c) population dynamics and food availability in the herbivorous tardigrade Apodibius confusus Dastych, 1983, d) tardigrade food preferences in the herbivorous Echiniscus granulatus (Doyère, 1840), Macrobiotus sapiens Pilato, 1984, M. persimilis Binda andPilato, 1972, Richtersius coronifer (Richters, 1903) and the carnivorous P. richtersi, e) life histories of some species and f ) different aspects of tardigrade histology (e.g. Suzuki 2003;Hohberg andTraunspurger 2005, 2009;Poprawa 2005Poprawa , 2011Hohberg 2006;Horikawa et al 2008;Hohberg et al 2011;Lemloh et al 2011;Schill et al 2011;Schill 2013), give us some incomplete information on tardigrade feeding behaviour.…”