A preface: it seems not a lot is known for certain about the shrimp Spongicola japonica or its host, Euplectella spp. What follows is a loose biopoetics of the ‘science’ that inspired this piece.
S. japonica shrimp are small, translucent shrimp sometimes pictured with an orange tint [though it was hard for me to tell if that was their actual color (unlikely) or perhaps some kind of image manipulation or stain]. When they are still very young, and thus small, these ocean bottom-dwelling shrimp find their way inside Euplectella spp. – sponges made of silicon that form a sort of lattice as pictured left. Two shrimp live in a sponge together, a male and female pairing, and grow up eating the nutrients “provided” by the sponge (it’s unclear to me if they eat algae off the spicules or get particulate matter that the sponge absorbs first or…); as they grow bigger and can no longer fit through the lattice of the sponge, they become trapped inside the sponge for life. After the pair reproduces, their young leave the sponge while they’re small enough to escape and go in search of their own place.
Euplectella spp. are thought to live on the abyssal plane (according to this website anyway), about 3000 to 6000 m deep. They are known for their fantastic spicules (what constructs the lattice) which have fiber optic qualities; since the spicules house bioluminescent bacteria, they glow quite consistently and brightly. The sponges grow on mud and hold themselves to it with fibers that grow like a messy ball at the end of the sponge. The sponges are relatively tall and thin, held up by rods (again, the spicules) which are covered in syncytium which seems to be a cob-webby mesh that catches particulate matter. Basically, these sponges are like a deep-sea skyscraper for shrimp.
The sponges can come detached from the mud and, eventually, they can wash up on beaches. In Japan, dried sponges containing two dead shrimp were given as gifts to couples at their weddings, considered to be a sign of eternal love and thus a symbol of good luck.