Red triangle slug

Coming in at up to 7cm in length, the red-triangle slug is Australia’s largest native land slug.

Red triangle slug

Article and images by Michael Mills, community conservation officer, Sunshine Coast Council

A sticky situation

Coming in at up to 7cm in length, the red-triangle slug (Triboniphorus graeffei) is Australia’s largest native land slug. The species is common in south east Queensland, particularly after rain. You may have seen signs of the slugs feeding before. They can often be found feeding on algae and lichens off of eucalypts, leaving lines of arc-shaped markings on smooth barked species.

There are three colours that can be found in south east Queensland. The most commonly observed is the white to cream colour with striking red triangle mantle shield on the back as well as red border of the foot. Yellow and red bodied forms also exist in greater Brisbane.

Within the red triangle you can also find the pneumostome or breathing pore. The slug also has a somewhat unique defence mechanism. When disturbed it secretes a sticky almost glue-like mucus, a different type of mucus to the thin, slimy one when moving around normally. This sticky mucus is capable of gluing predators in place for upwards of 24hrs. It remains strong whilst moist and weakens as it dries, leaving predators vulnerable to larger species and allowing the slug ample time to escape.