Bullia digitalis

{{Short description|Species of gastropod}} {{For|the Ancient Egyptian King|Finger Snail}} {{Use dmy dates|date=August 2020}} {{Speciesbox | image = Bullia digitalis - Plough snail 0350.jpg | image_caption = | genus = Bullia | species = digitalis | authority = (Dillwyn, 1817) | synonyms_ref = | synonyms = * ''Buccinum achatinum'' Lamarck, 1816 * ''Buccinum digitale'' Dillwyn, 1817 (original combination) * ''Buccinum elongatulum'' Anton, 1838 * ''Bullia (Bullia) digitalis'' (Dillwyn, 1817) · accepted, alternate representation * ''Bullia achatina'' (Lamarck, 1816) * ''Bullia almo'' Bartsch, 1915 * ''Bullia capensis'' Euthyme, 1885 * ''Bullia dulcis'' G. B. Sowerby III, 1921 * ''Bullia semiflammea'' Reeve, 1846 * ''Bullia semiusta'' Reeve, 1846 * ''Bullia soluta'' Turton, 1932 * ''Bullia sulcata'' Reeve, 1846 * ''Leiodomus quoyii'' Swainson, 1840 }}

'''''Bullia digitalis''''', the '''finger plough shell''', '''plough snail''' or '''surfing snail''', is a species of sea snail, a marine gastropod mollusk in the family Nassariidae, the Nassa mud snails or dog whelks.<ref name="WoRMS">{{WRMS species|225370|''Bullia digitalis'' }}</ref>

These dominant scavengers are attracted by the scent of decaying animal matter from a considerable distance so that they converge from all directions to feed.

==Description== Length: 60 mm

Narrow, smooth shell with a long, pointed spire, usually light yellow or creamy, often tinged with violet or yellow.<ref name=BRANCH>{{cite book |author=BRANCH, G.M. |author2=GRIFFITHS, C.L. |author3=BRANCH, M.L. |author4=BECKLEY, L.E. |name-list-style=amp |title=Two Oceans: A Guide to the Marine Life of Southern Africa |publisher=David Philip Publishers |location=Cape Town & Johannesburg |year=2002 |pages=360 |isbn=0-86486-250-4}}</ref><ref name=MATTHEWS>{{cite book |author=MATTHEWS, L. |title=The coastal guide of South Africa |publisher=Jacana Media |location=Johannesburg |year=2007 |pages=131 |isbn=978-1-77009-248-8}}</ref><ref name=PRENTER>{{cite book |author=PRENTER, C. |title=Geïllustreerde gids tot die dierelewe van Suider-Afrika |publisher=Sunbird Publishers |location=Kaapstad |year=2010 |pages=368 |isbn=978-1-920289-28-7}}</ref> The large, oval foot is offwhite.<ref name=BRANCH /><ref name=PRENTER /> The operculum has serrated margins.<ref name=BRANCH />

right|thumb|Movement of the Bullia digitalis

The ovate shell is elongated, subturreted, smooth and polished. It is of a reddish yellow color. The shell is composed of seven whorls, hardly convex. The suture which separates them is simple, shallow and submargined. The apex is moderately pointed. Pretty prominent striae of growth are seen upon the lowest whorl. The ovate aperture is smooth, widened at the middle and strongly emarginated at its base. The columella is yellowish, smooth and arched. A keel, continues from the upper third of the aperture to the base of the outer lip. The space between the keel and the edge of the lip is filled with oblique folds. The outer lip is simple, thin, sharp, and slightly effuse towards the middle.<ref name="Kiener">[https://archive.org/details/generalspeciesic00kien Kiener (1840). General species and iconography of recent shells : comprising the Massena Museum, the collection of Lamarck, the collection of the Museum of Natural History, and the recent discoveries of travellers; Boston :W.D. Ticknor,1837] (described as ''Buccinum achatinum'')</ref>

==Distribution== Lower east, south, south-west and west coast of South Africa.<ref name=MATTHEWS /> Best viewing: Kei Mouth.<ref name="VAN DEN BERG">{{cite book |author=VAN DEN BERG, J. |title=Keimouth shells |publisher=Kei Mercury |location=Kei Mouth |year=1993 |pages=6 }}</ref> [[File:Plough snail and bluebottle.jpg|300px|right|thumb|Plough snails eating a stranded bluebottle]]

==Status== Common to locally very common;<ref name=PRENTER /> the dominant plough shell on Atlantic shores.<ref name=BRANCH />

==Habitat== Sandy beaches along the surf zone,<ref name=MATTHEWS /> low on the shore<ref name=BRANCH /> from middle tidal zone seawards where the sand is not too coarse.<ref name=PRENTER />

==Behaviour== When the tide starts to rise, this snail emerges from the sand, spreads its large "foot" like a sail, and surfs up the beach in response to the smell of carrion.<ref name=BRANCH /><ref name=MATTHEWS /> The large foot is also used to burrow into the sand when the tide recedes.<ref name=MATTHEWS /> Sticks its proboscis into the prey to suck up soft tissues.<ref name=MATTHEWS /> Often gathers in large numbers to feed on dead and stranded jellyfish and bluebottles.<ref name=BRANCH /><ref name=MATTHEWS />

==Similar species== Various plough shells on the southern African coast look similar, including ''Bullia rhodostoma'' on the south coast and ''Bullia natalensis'' (pleated plough shell) on the coast of KwaZulu-Natal.<ref name=PRENTER /> ''B. digitalis'' however does not have pleated whorls like the pleated plough shell.<ref name=MATTHEWS /> All the common plough shells on the coast can only de differentiated for each other by their colour.<ref name=PRENTER />

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==See also== * ''Bullia natalensis'' * ''Bullia rhodostoma''

==References== {{Commons category}} {{Reflist}}

Category:Nassariidae Category:Gastropods described in 1817 Category:Articles containing video clips Category:Taxa named by Lewis Weston Dillwyn