December 12, 2017

Dogwhelk (Nucella lapillus)

Hard to imagine any snails in the bad boy predator role isn’t it? Well I know gardeners of all persuasions will already consider them as such, but hunting and eating other living creatures? Surely not!

Well this lot certainly do. Dogwhelks are a carnivorous snail species and mainly prey on sessile (immobile or fixed) species like Barnacles or Mussels, but can even tackle smaller Limpets. They use their radula (a modified toothed tongue-like structure) to bore a hole through the prey’s shell then inject a cocktail of anaesthetic and digestive enzymes before sucking their liquefied meal back out.

They were historically used to produce a red or purple and violet dyes like their Mediterranean cousins the Murex, who’s colours were highly valued in the ancient world.

Unlike our familiar garden snails and slugs who’re hermaphrodite (possessing male and female sex organs) Dogwhelks have distinct sexes. The females lay eggs like the ones above, many of which will be infertile and used as a food source for the babies, who emerge as tiny but perfect versions of the adults.

Fortunately this species is currently undergoing something of a renaissance as it recovers from the serious effects on its reproductive capabilities, brought about by the use of certain ‘anti fouling’ paints during the 70s. These products, which discourage marine organisms from attaching themselves to the hulls of boats, caused females in the wider Dogwhelk population to grow male sex organs, which blocked their egg laying duct and caused the males’ own organs to become oversized but infertile. This phenomenon, called imposex, totally wiped them out from certain parts of the UK coastline and seriously affected their numbers elsewhere, but they seem to be recovering well now.