Knobbed Top Snail
Diloma bicanaliculatum
- Usual depth0–6 m
- Water temperature12–18 °C
- Best monthsApril
- How commonRare
Photo credit: (c) Kelvin Perrie, some rights reserved (CC BY), uploaded by Kelvin Perrie · CC BY · iNaturalist
About this species
Diloma bicanaliculatum, common name the knobbed top shell, is a species of small sea snail, a marine gastropod mollusk, in the family Trochidae, the top snails. The size of the shell varies between 10 mm and 20 mm.
Text from the Wikipedia article “Diloma bicanaliculatum”, licensed CC BY-SA 4.0. Read the article
Where and when
Where it has been recorded
Worldwide
Loading the map
Best months
Worldwide (open data)
- January: 27 records
- February: 13 records
- March: 16 records
- April: 47 records
- May: 10 records
- June: 18 records
- July: 13 records
- August: 6 records
- September: 26 records
- October: 18 records
- November: 12 records
- December: 27 records
Depth and water temperature
Depth
Mostly recorded at 0–6 m · Deepest record: 11 m
Water temperature
Recorded in surface water of 12–18 °C
Photos
(c) wild_wind, some rights reserved (CC BY) · CC BY · iNaturalist 
(c) Javier, some rights reserved (CC BY) · CC BY · iNaturalist 
(c) wild_wind, some rights reserved (CC BY) · CC BY · iNaturalist 
(c) Javier, some rights reserved (CC BY) · CC BY · iNaturalist 
(c) Kelvin Perrie, some rights reserved (CC BY) · CC BY · iNaturalist 
(c) Christopher Stephens, some rights reserved (CC BY-SA) · CC BY-SA · iNaturalist 
(c) Kelvin Perrie, some rights reserved (CC BY) · CC BY · iNaturalist
Names and classification
- English
- Knobbed Top Snail
Other scientific names: Trochus bernardii, Trochus bicanaliculatus, Trochus cingulatus, Trochus gaimardi, Trochus sulcatus
Similar species
Scorched monodontDiloma aethiops
Speckled PeriwinkleDiloma concameratum
Mudflat Top ShellDiloma subrostratum
Bluish Top ShellDiloma nigerrimum
Sources and credits
Names and taxonomy: WoRMS (CC BY 4.0) and the GBIF Backbone (CC BY 4.0). Photos: iNaturalist observers, each under the licence shown (CC0, CC BY or CC BY-SA).
- Depth, temperature, months and maps: records from OBIS and GBIF under CC0 or CC BY.
- Descriptions: Wikipedia, licensed CC BY-SA, each linked to its article.
- Conservation status as published by GBIF (IUCN Red List).
- 371 open-data records from 1934 to 2012.
- Species data updated November 2, 2026.
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