Red slug

Arion rufus

The red slug, also known as the chocolate arion or the European red slug, Arion rufus, is a large land slug, a terrestrial pulmonate gastropod mollusk in the family Arionidae, the roundback slugs. This species is characterised by its (usually) red or brown body and lack of a keel.
Red slug - Arion rufus Meerdaelbos, November 2015.  Arion rufus,Belgium,Fall,Geotagged,Red slug

Appearance

At most, a full-grown red slug can extend to be approximately 18 cm (7 in) in length; although they usually only grow to be 7–10 cm (2.7–3.9 in) long.

Its genus, Arion, is derived from the name of the legendary Greek poet Arion. Its species name, rufus, is Latin for red. Although very often brick-red or brown in coloration, Arion rufus can also be greenish-brown, black, yellow, or orange.
Head-on view of red slug
Red slug on rhubarb in a garden
Copulating pair and a third party
Egg cluster surrounded by earth

Perhaps the red slug's most noticeable feature is the placement of its pneumostome just before the mid-point of its mantle. Like all slugs, the red slug moves relatively slowly, using the muscular contractions of the underside of its foot, which is mostly red with stripes.

The red slug, like all other slugs, uses two pairs of tentacles to sense its environment. The darkly-coloured upper pair, called optical tentacles, is used to sense light. The lower pair provide the red slug's sense of smell. Both pairs can retract and extend themselves to avoid hazards, and, if lost to an accident or predation, can be regrown.
Red Slug out for a stroll These are very common in the forests of Southern Germany where I live but still pretty cool. After it rains, there are hundreds on the trails in any forest. I have always wondered why no predator after all the time of evolution has apparently ever developed a taste for such a readily available food source (although I have read that some reptiles and even Hedgehogs will eat them on occasion). Arion rufus,Geotagged,Germany,Red slug,Summer

Distribution

This slug is mostly found in Denmark, where it was a was introduced by some scientists in a forrest near Silkeborg in 1913. And with help from people, it spread to the rest of East Jutland where it, by itself, spread to:

Germany, Luxembourg, Poland, Sweden, Norway and Great Britain
Red slug on Sulphur Tuft Red slug (Arion Rufus) on Sulphur Tuft (Hypholoma Fasciculare) Arion Rufus,Geotagged,Hypholoma Fasciculare,Red slug,Sulphur Tuft,The Netherlands,closeup,mushroom,snail

Habitat

The red slug typically lives in gardens, fields, or wooded areas near human activity.

References:

Some text fragments are auto parsed from Wikipedia.

Status: Unknown
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Taxonomy
KingdomAnimalia
DivisionMollusca
ClassGastropoda
OrderPulmonata
FamilyArionidae
GenusArion
Species