Yesterday, when I was out snorkeling, I was spotted this entity hanging in the water. When I first saw it, I thought it might be a pyrosoma. I was lucky enough to see one of those last year, which I posted about here. Pyrosoma are colonies of many individual tunicates and this new sighting looked somewhat similar. But where that pyrosoma looked like a gelatinous tube with little purple dots in it, this tube was longer, thinner, and had much larger, and clearly visible, brown spots in it.
After some research, I’m pretty sure this is a chained salp. Like pyrosoma, chained salps are colonies of individuals. The individuals have a heart, gills and a spinal cord, which makes them quite advanced in evolutionary terms. They move around by pumping water through their bodies. When they form chains, the individuals in the chains communicate with electrical signals so the the chain moves in harmony.
Typically, salps are creatures of the open ocean, and not often seen in Hawaii, so I feel quite fortunate to have seen this one.