Sunday, 24 May 2015

Dryas octopetala and a crafty spider

Freshly opened flowers of Dryas octopetala on a cliff top 

There are outcrops of limestone in the Durness area of north-west Scotland and the resulting soil offers suitable growing habitat for base-loving plants such as the Mountain Aven Dryas octopetala. These Arctic-alpine plants seem to almost grow on the bare rock in places, the soil is so thin, and they can also grow on the sea-cliff tops where there is more than a little shell sand blown in by the Atlantic winds. In places, there are large creeping carpets of the plant's glossy green leaves, and now the flowers are opening, showing their distinctive eight petals from which they are named. Although not all the flowers have eight petals.

As their name suggests, eight petals are the norm

I was creeping about on a rock face, balancing the camera as I tried to photograph the flowers and the plants in their habitat, when I noticed a crab spider lying in wait on one of the flowers. Patiently waiting for an insect to land on the flower for a sip of nectar, when it would pounce and grab it.

A crab spider waits in ambush, forelegs held aloft ready to strike

These spiders don't spin webs, they rely on ambush to catch their meal. The front two pairs of legs of a crab spider are adapted to catch their prey, and they are held up high and open while the spider waits. While it waits, the spider lies facing the centre of the flower, ever ready to jump at an insect as it lands on the nectar-baring flower parts.

The two pairs of fore legs are for catching, the hind two pairs for standing, then jumping
However, after numerous attempts to find an on-line guide to what species I found, I am non the wiser. So, if anyone can help identify this spider please do add a comment below.

But - what is the species?


  1. Hi Stuart, I'm not spider expert, but I recently blogged about a very similar looking spider (smallscale safari, April, The Stake Out) and did some work on trying to identify it. This website might be a useful place to start, even though it relates to Leicestershire, but I believe these species are quite widespread: . I didn't get mine down to species, as it said that identifying by photo is not possible, and the spider needs to be examined. Good luck!

  2. Thanks Chloe, I have seen similar spiders in similar mid-flower positions like your one. So I keep an eye out for more in all sorts of flowers. And I have tried again to identify my one, but can only be confident to the genus of Xysticus. It looks like X. cristatus, but as it was on base-rich habitat it could be X. erraticus, Or perhaps another species not listed on any of the websites I have accessed. If anyone can advise please do.