Gyraulus crista
Conservation status
Least Concern (IUCN 3.1)[1]
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Heterobranchia
Superorder:	Hygrophila
Family:	Planorbidae
Genus:	Gyraulus
Subgenus:	G. (Armiger)
Species:	G. crista
Binomial name
Gyraulus crista (Linnaeus, 1758)[2]
Synonyms
Nautilus crista Linnaeus, 1758 Armiger crista (Linnaeus, 1758) Planorbis crista (Linnaeus, 1758)

Gyraulus crista, commonly called the Nautilus ramshorn, is a minute species of freshwater snail, an aquatic pulmonate gastropod mollusk in the family Planorbidae, the ram's horn snails.

Subspecies

Subspecies include:

• Gyraulus crista cristatus Draparnaud, 1805
• Gyraulus crista nautilus Linnaeus, 1767
• Gyraulus crista spinulosus Clessin

Distribution

The distribution of this species is Holarctic (spread across the northern part of the whole northern hemisphere). The distribution type is circumpolar wide-temperate, and the range includes:

• Czech Republic^[3] - least concern (LC)^[4]
• Slovakia^[3]
• Germany
• Italy
• Netherlands^[5]
• Sweden
• The British Isles, Great Britain, Ireland
• See Fauna Europaea for European distribution.

Shell description

The minute shell is nearly planispiral in its coiling, but the spire is actually considerably sunken rather than raised (which is usually the case with gastropods).

The shell has regular transverse ridges which form points extending beyond the main curve of the periphery of the shell.

The shell color is a translucent yellowy-brown. The maximum shell dimension is about 3 mm.

Ecology

This snail lives on water plants in clear still freshwater. In Ireland it is common in medium to very small habitats including slow streams, drains and marsh and fen pools It is occasionally found in very acid waters.

This minute species, although technically a pulmonate gastropod, does not use air for respiration but instead absorbs oxygen through its mantle cavity which is full of water.