For the @printersolstice #printerSolstice2425 prompt copper, I made a #linocut horseshoe crab (Tachypeus gigas) in grey, blue-bronze and dark brown on 8" x 8" cream-coloured Japanese paper with bark inclusions. They get their name from their horseshoe like shape but they are not crabs; they are chelicerates, more closely related to arachnids and they are "living fossils" which have changed very little since 
they first appeared in the Triassic. The textured sandy paper is meant to look like sand on a beach. They actually swim with their underside up, but prefer to stay on the sea bottom, so this one is crawling not swimming.
There are 4 species of horseshoe crab which are still living. T. gigas is a species from the Indo-Pacific. The blood of horseshoe crabs (like most mollusks) contains the copper-containing protein hemocyanin rather than hemoglobin (the iron-containing protein), 2/n
which is the basis of oxygen transport in vertebrates. Colourless when deoxygenated hemocyanin turns dark blue when oxygenated. In circulation, the horseshoe crab's blue is grey-white to pale yellow, but if exposed to air when they bleed, it turns dark blue. Hemocyanin carries oxygen in extracellular fluid, unlike the oxygen transport in vertebrates by hemoglobin in red blood cells. 3/4
Tachypleus gigas inhabits seagrass meadows, sandy and muddy shores at depths to 40 m (130 ft) and is the only horseshoe crab to have been observed swimming at the surface of the ocean. It lives in both marine and brackish waters in tropical South and Southeast Asia.
https://minouette.etsy.com/listing/1858784172
4/4