28 Testudinalia testudinalis. Littoral. Moray Coast, Banffshire, Scotland. May 2017. Leg. S. Taylor.

28 Testudinalia testudinalis. Littoral. Moray Coast, Banffshire, Scotland. May 2017. Leg. S. Taylor.

Marks left by the front four teeth on the printed surface of a polythene sheet show that specimens with shells c.14mm long make straight thrusts of about 0.5mm at each stroke.
Faeces (at same scale, on left) contained comminuted black print ink encased in mucus. Compaction with mucus prevents fouling of the ctenidium.

APPENDIX re range advance/retreat: flic.kr/p/2jW74ig

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