APHOTOMARINE

An educational resource dedicated mainly to the photography
and diversity of marine life that can be found in coastal waters
and intertidal areas of Great Britain and Ireland by David Fenwick.

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Spider crab
Achaeus cranchii
- with 0.1mm rule 1

Spider crab
Achaeus cranchii
- dorsal view 1

Spider crab
Achaeus cranchii
- dorsal view carapace 1

Spider crab
Achaeus cranchii
- tuberculed eye pair 1

Spider crab
Achaeus cranchii
- tuberculed eye 1

Spider crab
Achaeus cranchii
- claws 1

Spider crab
Achaeus cranchii
- claw of hind leg 1

Specimen above found by the author under a rock on an extra low tide at Hannafore, Cornwall, 30.03.2017.

Spider crab
Achaeus cranchii
- dorsal view / in-situ 1

Specimen above found by the author under a rock on an extra low tide at Hannafore, Cornwall, 01.02.18. The above was one of three specimens found that day.

Typical dimensions of male carapace 11mm x 9mm. Possibly overlooked as the species appears similar to a juvenile Macropodia rostrata, most of the identification features may be hidden, but the lack of a rostrum, eye pair with tubercules and the toothed hinds claws are quite distinctive.

Please note, Spider crabs can be quite tricky to identify with any certainty because of a covering of algae. This means verification from images may be impossible. It may be necessary to remove some of the algae with fine tweezers in order to identify weed covered specimens using a stereomicroscope and key. It is too easy to assume specimens are the common Macropodia rostrata, when they may not be, and detailed examination is important if under-recorded species are to be found and identified.

The main objective of this website is in furthering environmental awareness and education through the medium of photography. To increase awareness and access to the wildlife of the region and help

people find and identify it. Sometimes the difference between species is obvious but many species can only be determined by observing microscopic characteristics that are specific to any one species.