Nick Hawkins / European green crab (Carcinus maenas), an invasive species in North America, Kejimkujik Seaside National Park, Nova Scotia, Canada. July.

Michael Hutchinson / Flower crab spider (Misumena vatia) female with red and green stripes, on Saxifraga flower, Bristol, UK, May

Nick Upton / Close-up of a Shore crab (Carcinus maenas) in a rock pool, moving mouth parts, Gower Peninsula, Glamorgan, Wales, UK, August.

Nick Upton / Common or Green shore crab (Carcinus maenas) hiding in a rock pool, The Gower Peninsula, Wales, UK, August.

Nick Upton / Common shore crab (Carcinus maenas) hiding among Coralweed (Corallina officinalis) in a rock pool, Cornwall, UK, March.

Nick Upton / Close-up of a Common shore crab (Carcinus maenas) in a rock pool, vibrating its maxillae to aerate its gills and flicking its antennae, Cornwall, UK, March.

Nick Upton / Close-up of a Common shore crab (Carcinus maenas) in a rock pool, vibrating its maxillae to aerate its gills and flicking its antennae, Cornwall, UK, March.

Nick Hawkins / Comparison of the invasive European green crab (Carcinus maenas) on left to native Atlantic rock crab (Carcinus irroratus) on right. Kejimkujik Seaside National Park, Nova Scotia, Canada. July.

Nick Hawkins / Invasive European green crab (Carcinus maenas) with eel grass (Zostera marine) in Kejimkujik Seaside National Park, Nova Scotia, Canada. July.

Nick Hawkins / European green crab (Carcinus maenas), an invasive species in North America, Kejimkujik Seaside National Park, Nova Scotia, Canada. July.

Nick Hawkins / Invasive European green crabs (Carcinus maenas) collected by park staff in Kejimkujik Seaside National Park near Port Joli, Nova Scotia, Canada. July.

SCOTLAND: The Big Picture / Horse mussel bed (Modiolus modiolus) with Brittle stars (Ophiothrix fragilis),Edible crab (Cancer pagurus) and Northern sea urchin (Strongylocentrotus droebachiensis) Sheltand Islands, Scotland, UK, S...

Terry Whittaker / Herring gull (Larus argentatus) with shore crab (Carcinus maenas ), Chanonry Point, Moray Firth, Highlands, Scotland. June.

Terry Whittaker / Herring gull (Larus argentatus) with Shore crab (Carcinus maenas ) prey, Chanonry Point, Moray Firth, Highlands, Scotland. September.

Terry Whittaker / Herring gull (Larus argentatus) with Shore crab (Carcinus maenas ), Chanonry Point, Moray Firth, Highlands, Scotland. June 2017

Nick Upton / Young boy watches as a Shore crab (Carcinus maenas) caught in a rockpool is placed in his bucket, Cornwall, UK, October. Model released.

Nick Upton / Young boy watches as a Shore crab (Carcinus maenas) caught in a rockpool is placed in his bucket, Cornwall, UK, October. Model released.

Nick Upton / Young boy watches as a Shore crab (Carcinus maenas) caught in a rockpool is placed in his bucket, Cornwall, UK, October. Model released.

Lorraine Bennery / Crab spider (Thomisus onustus) feeding on Green-veined white butterfly (Pieris napi), Verdon Regional Natural Park, France, June.

Andy Sands / Crab Spider (Diaea dorsata) a woodland species well camouflaged on this hazel leaf to ambush prey, Surrey, England, UK. July

Pascal Pittorino / Crab spider (Heriaeus hirtus) resting on Common hedge parsley (Torilis arvensis) plant in garden, Var, Provence, France, June

Kim Taylor / Crab spider (Heriaeus sp) Bulgaria, July.

MYN / Tim Hunt / Running crab spider (Philodromus dispar) Barnt Green, Worcestershire, UK, April. meetyourneighbours.net project

MYN / Tim Hunt / Crab spider (Xysticus cristatus) Barnt Green, Worcestershire, UK, June. meetyourneighbours.net project

Sue Daly / Shore Crab (Carcinus maenas) on sea shore, Guernsey, British Channel Islands.

Sue Daly / Shore Crab (Carcinus maenas) on sea shore, Guernsey, British Channel Islands.

Stephen Dalton / Green Hairy Crab spider (Heriaeus hirtus) Corfu, Greece, May.

Alex Hyde / Shore Crab (Carcinus maenas) female carrying eggs with claws raised in defensive posture. Northumberland, UK. May.

Alex Hyde / Shore Crab (Carcinus maenas) female carrying eggs with claws raised in defensive posture. Northumberland, UK. May.

MYN / Tim Hunt / Crab spider (Thomisidae) on Oxeye daisy (Leucanthemum vulgare) Barnt Green, Worcestershire, UK, June. Meetyourneighbours.net project

Benjamin Barthelemy / Shore crab (Carcinus maenas) at low tide, Calvados, Normandy, France, July.

Benjamin Barthelemy / Shore crab (Carcinus maenas) at low tide, Calvados, Normandy, France, July.

Nick Upton / Montagu's / Furrowed crab (Lophozozymus incisus / Xantho hydrophilus) by green algae, near Falmouth, Cornwall, UK, August.

Nick Upton / Montagu's / Furrowed crab (Lophozozymus incisus / Xantho hydrophilus) hiding behind green algae, near Falmouth, Cornwall, UK, August.

Alan Williams / Crab apple (Malus sylvestris) fruits on tree grown at roadside in Cheshire village, UK, October.

Alan Williams / Crab apple (Malus sylvestris) fruits on tree grown at roadside in Cheshire village, UK, October.

Alan Williams / Crab apple (Malus sylvestris) fruits on tree grown at roadside in Cheshire village, UK, October.

MYN / Paul Harcourt Davies / Goldenrod crab spider (Misumena vatia) on green plant, Italy, June. meetyourneighbours.net project

MYN / Paul Harcourt Davies / Goldenrod crab spider (Misumena vatia) on green plant, Italy, June. meetyourneighbours.net project

MYN / Paul Harcourt Davies / Goldenrod crab spider (Misumena vatia) on green leaf, Italy, June. meetyourneighbours.net project

MYN / Paul Harcourt Davies / Hairy green crab spider (Heriaeus hirtus) on green leaf, Italy, June. meetyourneighbours.net project

MYN / Paul Harcourt Davies / Hairy green crab spider (Heriaeus hirtus) on green leaf, Italy, June. meetyourneighbours.net project

MYN / Paul Harcourt Davies / Hairy green crab spider (Heriaeus hirtus) on green leaf, Italy, June. meetyourneighbours.net project

MYN / Paul Harcourt Davies / Hairy green crab spider (Heriaeus hirtus) on green leaf, Italy, June. meetyourneighbours.net project

MYN / Paul Harcourt Davies / Hairy green crab spider (Heriaeus hirtus) on green leaf, Italy, June. meetyourneighbours.net project

Paul Harcourt Davies / Green hairy crab spider (Heriaeus hirtus) camouflaged on vegetation, Italy, Europe.

Paul Harcourt Davies / Green hairy crab spider (Heriaeus hirtus) camouflaged on vegetation, Italy, Europe.

Stephen Dalton / Goldenrod crab spider (Misumena vatia) juvenile, UK