It’s a Pyrosome…or maybe not!
Updated March 8, 2015Original <Back in 2009 I encountered a really strange creature while snorkeling off of Cabilao Island, Philippines. It was long and tubular (about a meter and a half long and 20 cm in diameter) with rings consisting of tiny pink balls along the entire length of it. I honestly had no idea what it was, and things like a jelly, salps, an egg case, trash, and several other absolute guesses crossed my mind. Unfortunately, I couldn’t find anything that looked close enough to it and moved on to other things.
Flash forward to, well, today. Today I read about a rare encounter with a pyrosome, and upon looking at the pictures and video (which can be seen here) knew immediately that this was my mystery organism I had encounter five years ago!
Pyrosomes (order Pyrosomatidae) are related to salps, a type of pelagic, colonial tunicate. The entire colony is made up of thousands of individual zooids fixed in a gelantinous material called the tunic. In this photo, the stomach of each zooid can clearly be seen as the tiny pink balls. Each zooid is responsible for filtering the water for its primary food item, phytoplankton, and reproduction. Pyrosomes are bioluminescent and often flash a blue-green light visible from several meters away. It is this behavior that earned them their name, Pyrosoma (from pyro=fire and soma=body).
Pyrosomes drift in the upper depths of tropical seas but remain pelagic, and, thus, why people rarely encounter them. Some scientists even go as far as referring to them as unicorns of the sea, given they are so rarely seen they almost fall into the ‘mythical beast’ category. As snorkelers and divers we often feel it is a privilege to have intimate encounters with the myriad of marine organisms that inhabit coral reefs. In this case, I feel very lucky as well!>
UPDATE: The internet as a resource comes through again. As I wrote above, I had no idea what it was and only made the connection when I read a news piece about an encounter with a similar organism off Ticao Island, Philippines. The next day, I got a massage on my facebook account from a fellow that said he was told this is the egg case of a deep water squid called a rhomboid (or diamondback) squid (Thysanoteuthis rhombus). After searching, I am inclined to agree, though with only the smallest of reservations due to the fact that I have not had the chance to really investigate this on a detailed level (e.g., looking at the eggs or zooids through a microscope to see if they were, indeed, the former or latter). During my initial encounter, an egg case was on my shortlist of suggestions and though I still leave the absolute identification to those who are better informed about deep water squid or pelagic tunicates, I feel more confident hanging out in the camp with those that identify it as an egg case.