“Phosphorescence” of Pennatulida

Abstract

PROF. NEWSTEAD and I have had two of the few British Pennatulida—Pennatula phosphorea and Funiculina quadrangularis—“phosphorescing” to-day before our eyes, so it may be worth recording the impressions while they are fresh. Pennatula phosphorea, as its name indicates, has long been known to emit light, and, writing from memory, I think Sir Wyville Thomson, in his “Depths of the Sea”, refers to the “lilac phosphorescence of Pavonaria” (= Funiculina). Prof. Newstead and I have just seen the colour and distribution of the light very clearly in a makeshift dark-room (the lazarette of the yacht), and also on the deck at midnight. In Funiculina the distribution of the luminosity is very curious and quite different from that of Pennatula. There are many distinct sparkles over the polype-bearing part of the colony (corresponding, no doubt, to the individual polypes), but the long, bare lower part of the stem, 9 in. to a foot in length, when gently stroked in the dark glows with a continuous sheet of light of (it seems to me) a pale-green colour which flickers or pulsates like a lambent flame. The light on this bare part of the colony is certainly more intense than that of the polypes, and is the most brilliant “phosphorescence” I have seen in any marine animal. I have not seen Pyrosoma alive, but I imagine from the descriptions it may be even more brilliant than Funiculina.