(Phipps, 1774)
Full name (Van der Spoel et al., 1997): Clione limacina (Phipps, 1774) subsp. limacina (Phipps, 1774) forma limacina (Phipps, 1774)
Description
A naked pelagic snail, up to 4 cm long, with a mainly transparent body that only shows orange-red colouration in the tail, tentacles and mouth organs. The reddish-brown visceral mass is seen through the body wall. [Clione l.l. limacina].
The species has a barrel-shaped body, pointed posteriorly. Gills are absent. The visceral mass reaches no further than half the length of the body. There are three pairs of buccal cones of which the dorsal pair is slightly larger than the ventral ones [C.l.l.limacina-buccal]. The cones are arranged so that the base of the three left cones touch, as do the bases of the three right cones. The skin has no chromatophores. The footlobes are well developed, the posterior one is moderately long. The radula formula varies between 6-1-6 and 15-1-15 [C.l.l.limacina-rad1, C.l.l.limacina-rad2]. The median plate usually has a small central cusp and numerous very small denticles. Hook sacs are medium sized with numerous slightly bent hooks, unequal in size [C.l.l.limacina-hooks].
Juveniles: only the very young larvae have a shell [C.l.l.limacina-prc]. The aperture is slightly oval. Protoconch II is nearly as long as protoconch I and becomes increasingly wider, it has many growth lines and longitudinal striae. Protoconch I is oval to round but is always slightly pointed posteriorly. There is no clear incision between protoconch I and II.
Ecology
A rather quick swimmer that hunts shelled pteropods as food. It lives in the N-Atlantic and N-Pacific Oceans in the upper water layers where it can occur in mass blooms.
Distribution in the North Sea
Occurs in the northern North Sea.
World distribution
Found in the N-Atlantic and N-Pacific Oceans. The forma limacina is, however, a boreo-oceanic element, when it penetrates shallow waters, reproduction is sometimes not executed. However, juveniles are found and reproduction to also occur in shallow waters. The different formae represented by this species are explained by the stenotherm character of the populations. For the forma limacina a temperature range of -1.7° to +6.2°C was found.
Remark
The hyperiid amphipod Hyperiella dilatata, uses living specimens of C. l. l. limacina as a chemical defence system.
[After Van der Spoel et al., 1997]