Tardigrada, or water bears, are microscopic aquatic invertebrates found in many land and sea habitats. Ultrastructure studies have tried to show their true affinities to other invertebrates. Physiologists are trying to understand how they can survive such extreme heat, cold and caustic chemicals. One of the biggest problems is to define a species. Collections were taken from as many locations as was practical so that speciation could be better understood. Collections were made in 1970 and 1975 from several areas includeing Ross Island (Cape Bird, Cape Royds, Cape Evans, Cape Crozier, Observations, Crater Hill and Beach Crater near Castle Hill), Cape Hallett, Marble Point, Discovery Bluff (Granite Harbour), Spike Cape, Dunlop Island, Hjorth Hill, Lake Fryxell, Lake Bonny, Suess Glacier, the Strand Moraines, Blue Glacier, Arneb Glacier, Scallop Hill (Black Island) and Mt Discovery.