Panasonic LUMIX GX8 + Olympus M.Zuiko 60mm f2.8 Macro, ISO 1250, 1/125 s, f/7.1 This week's picture shows a crab spider on a leaf. Crab spiders or Thomisidae are a very common family of spiders with over 2100 species. The sample here is a small Xysticus species. Crab spiders are distinguished by their large and strong front four legs which are used to catch prey.