Echiniscoides sigismundi is a species of marine tardigrade. It lives in seaweeds or plates of barnacles, or more generally in algal strongholds in inter-tidal areas.
Echiniscoides sigismundi is the type species of Echiniscoides. Described in 1865 as Echiniscus sigismundii, it was placed in a separate genus by Ludwig Hermann Plate in 1888.
By 1936, it was reported in most seas of Northern Europe, and in the Mediterranean and the Caribbean.
The Light and Smith Manual describes its distribution as cosmopolitan, in the upper inter-tidal.
Echiniscoides sigismundi becomes turgid in freshwater, but can survive up to three days, resuming normal activity as osmotic differential returns to normal.