Taxonomic Correlates of Bioluminescence Among Appendicularians (Urochordata: Larvacea)

Abstract

Larvaceans, common members of marine plankton communities, filter-feed with renewable, external, mucous houses. The houses of some species of Oikopleuridae produce endogenous bioluminescent flashes upon mechanical stimulation and may contribute significantly to surface luminescence. To determine which members of the Oikopleuridae are luminescent, we examined several species for stimulable luminescence and for morphological features responsible for or associated with light production. Luminescence is newly reported from house rudiments and from clean, particle-free houses ofOikopleura rufescens and Stegosoma magnum. In these species, light emanates from previously undescribed fluorescent inclusions in the house rudiment. Neither fluorescence nor luminescence were detected from other parts of the body. Both species also possess oral glands, which apparently are not directly involved in light production but serve as a convenient taxonomic marker of luminescence. All six known luminescent species of larvaceans possess fluorescent and luminescent house rudiment inclusions and oral glands. We predict on these morphological grounds that all twelve species of Oikopleura (Vexillaria) plus the oikopleurids S. magnum and Folia gracilis are luminescent. In two other oikopleurids that lack oral glands, O. fusiformis and Megalocercus huxleyi, neither fluorescent inclusions nor luminescence were detected in clean houses and animals with house rudiments. However, some field-collected houses of these species produced luminescent flashes, perhaps from dinoflagellates on or in the houses. This report should facilitate assessment of the contribution of larvaceans to surface luminescence on a global scale.

Ecology of Anguilliform Leptocephali: Remarkable Transparent Fish Larvae of the Ocean Surface Layer

“…Because marine snow is most abundant in the surface layer where leptocephali live, it is a logical food source for them. Some larvacean houses (Galt et al 1985) and some types of marine snow (Herren et al 2004) have bioluminescent properties that could make it possible to be seen and eaten at night by leptocephali which appear to be adapted for night vision. It remains to be determined, however, under what types of light conditions and depths leptocephali feed on particulate material.…”

Systematic distribution of bioluminescence in living organisms

“…Bioluminescence is regarded as uncertain in genera that are listed but not italicized. (Galt et al, 1985) Sub-phylum CEPHALOCHORD ATA Sub-phylum VERTEBRATA (Herring and Morin, 1978 …”

Ontogenetic changes in phototactic behavior during metamorphosis of artificially reared Japanese eel Anguilla japonica larvae

“…They may be able to feed at night because at least some marine snow has recently been shown to be bioluminescent due to microorganisms such as dinoflagellates attached to it (Herren et al 2004). Even the discarded houses of some species of larvaceans are bioluminescent (Galt et al 1985). This could allow leptocephali to visually target this food material in darkness.…”