Comparison of the biology and freezing tolerance of Panagrolaimus davidi, an Antarctic nematode, from field samples and cultures

Samples of Panagrolaimus davidi, an Antarctic nematode which tolerates intr acellular freezing, were collected from Cape Bird, Ross Island and compared with nematodes cultured for nine years. The field distribution of nematode s was patchy and was not correlated with the water content of the sample or the presence of algae. Field-collected nematodes were similar in morpholog y to those from cultures, although there were differences in morphometrics. Males predominated in field material, whereas cultures contained only part henogenetic females. The freezing tolerance of field-collected nematodes wa s similar to those from cultures. Nematodes in culture are thus a valid mod el for the study of the adaptations involved in the survival of the extreme environmental stresses faced by these animals in their Antarctic habitats.