Juergen Freund / Sea pen porcelain crabs (Porcellanella triloba) in sea pen (Pteroides sp.). Lembeh Strait, North Sulawesi, Indonesia.

Georgette Douwma / Pen Crab (Porcellanella triloba) perched in Sea Pen (Virgularia sp.), from where the crab filter feeds in the current. Rinca, Indonesia. October.

Georgette Douwma / Pen Crab (Porcellanella triloba) perched in Sea Pen (Virgularia sp.). Filter feeding setae mouthparts of the crab are visible. Rinca, Indonesia, October.

Georgette Douwma / Sea pen porcelain crab (Porcellanella triloba) in Sea pen (Virgularia gustaviana) Porcelain crabs are filter feeders and climb in the sea pen to take advantage of current. When the Sea pen retreats in...

Georgette Douwma / Sea pen porcelain crab (Porcellanella triloba) in Sea pen (Virgularia gustaviana) Porcelain crabs are filter feeders and climb in the sea pen to take advantage of current. When the Sea pen retreats in...

Georgette Douwma / Pen crab (Porcellanella triloba) resting in Sea pen (Pteroeides) to feed on plankton, Rinca, Indonesia

Chris Newbert / Porcelain Crab (Porcellanella sp) camouflaged on Sea Pen (Virgularia sp), Indonesia