Tom,
 
On Scaphander lignarius there is a paragraph on page 116 in Living Marine
Molluscs by C. M. Younge and T. E. Thompson, published in 1976 that
describes what they eat.
 
"We return to the ocean bottom to consider two common British
opisthobranchs that burrow through sand and muddy sand, searching for
infaunal bivalves which are swollowed intact.  The largest of these
carnivores is the amber-colored Scaphander lignarius (Fig. 56) which may
reach an overall length of 6 cm (greater in Mediterranean specimens).
The swollen, pale body is much too large to be accommodated within the
shell, and these rather coarse-looking animals are commonly dredged in
shallow sublittoral sand; it is often difficult to be sure whether a
specimen is alive or dead, they are so relatively helpless when removed
from the sandy substrate.  But in nature it is a different story, and a
Scaphander can consume, rapidly and efficiently, many kinds of bivalves,
as well as some polychaete worms, echinoderms and gastropods.  Ti is
iteslf said to be eaten by haddock, one of the few authenticated reports
of any opisthobranch being taken as food by a fish, or, for that matter,
by any predator."
 
Suggest you contact Steve Long.  He has posted notes to CONCH-L from time
to time, so you should be able to find his e-mail address in the archives
- if he does not respond to your query about an opisthobranch.  He has
pubished a newsletter on the group for a long time.
 
Good luck in your search for information...
 
Bill Fenzan
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