Crab spider (Misumena vatia)

KingdomAnimalia
PhylumArthropoda
ClassArachnida
OrderAraneae
FamilyThomisidae
GenusMisumena (1)
SizeMale length: 3-4 mm (2)
Female length: 9-11 mm (2)

Not threatened (2)

There is just a single species in Britain belonging to the genus Misumena (2). As the common name suggests, it is reminiscent of a crab, with its wide, flattened body form and habit of sitting with the first pair of legs held apart (3). This spider has the remarkable ability to alter its colour to match its background, usually a white or yellow flower, allowing it to become beautifully camouflaged (3). The sexes are different in appearance; females vary in colour from white to pale green or yellow, depending on the background. They tend to have two pairs of bright red spots on the abdomen, but these may be fused to form red lines or even entirely missing. Males are much smaller in size than females and have more slender greenish white abdomens that feature brown stripes (2).

In Britain, this spider is found mainly in southern England (2). It is also found throughout much of mainland Europe and North America (3).

The crab spider can be found on flowers and shrubs (2) in gardens, woodlands, grassland, and scrubby habitats (4).

This species does not spin a web to catch its prey. Instead it lies in wait on flowers and vegetation for a suitable prey species to visit and swiftly ambushes the insect (2) (3). It then injects venom into the prey with the slender fangs (3).

Males deposit a drop of sperm which is taken up by specialised leg-like appendages known as ‘palps’. During copulation, the sperm is passed to the female’s reproductive organ (the ‘epigyne’). After mating, the female lays the eggs, folds a leaf over them and spins a protective silk cocoon around the folded leaf. She will then cease to feed and stands guard over the eggs for around three weeks, after which the eggs hatch and the female dies (3).

This spider is not threatened.

Conservation action is not required for this common species.

For more on invertebrates and their conservation see Buglife, the invertebrate conservation trust:
http://www.buglife.org.uk/

For more on British spiders see The British Arachnological Society:
http://www.britishspiders.org.uk/

Information authenticated by Dr Peter Merrett of the British Arachnological Society:
http://www.britishspiders.org.uk/index.html

  1. National Biodiversity Network Species Dictionary (January 2004)
    http://www.nhm.ac.uk/nbn
  2. Roberts, M. J (1993) The spiders of Great Britain and Ireland, part 1- text. Harley Books, Colchester.
  3. Animal diversity Web (January 2004)
    http://animaldiversity.ummz.umich.edu/site/accounts/information/Misumena_vatia.html
  4. Essex Field Club (January 2004)
    http://www.essexfieldclub.org.uk/form_misumena.htm