Terebelliformia is a benthic group of marine annelid worms. The bioluminescence of several species has been reported in taxonomical and histological literature, but very little information is known about the biochemical aspects of this phenomenon. In this study, we examined the basic properties of the luminescence system using an extract of the Japanese terebelliform worm, Thelepus japonicus. The bioluminescence extract was soluble in water, and emitted blue-green light at λ max 508 nm following the addition of divalent cations. This triggering action was highly specific to Fe 2+ and addition of ATP, H 2 O 2 or coelenterazine did not enhance activity. The bioluminescence was inactivated by heat treatment and organic solvents, indicating the involvement of a protein component. These results suggested that Thelepus worm produces light using a novel system that differs from that in other known luminescent annelids.

Pontodrilus litoralis is a cosmopolitan littoral earthworm known to exhibit bioluminescence. Recently, a congeneric species, Pontodrilus longissimus, from Thailand was described. These species are sympatric, but their burrowing depths on Thai beaches are different. In this study, we examined the in vivo and in vitro bioluminescent properties of P. longissimus and P. litoralis. Mechanical stimulation induced in vivo luminescence in P. litoralis, as reported previously, but not in P. longissimus. In vitro cross-reaction tests between these species revealed the absence of luciferin and luciferase activities in P. longissimus. The coelomic fluid of P. litoralis had strong fluorescence that matched the spectral maximum of its bioluminescence, but the same result was not observed for P. longissimus. These results suggest that P. litoralis has luminescence abilities due to the creation of bioluminescent components (i.e., luciferin, luciferase, and light emitters). The presence of both luminous and nonluminous species in a single genus is likely widespread, but only a few examples have been confirmed. Our findings provide insight into the possible functions of bioluminescence in earthworms, such as avoiding predation by littoral earwigs.

Commercially pumped deep-seawater is an easily accessible source of deep-sea animals. In this study, we report the bioluminescence of a cirratulid polychaete, Tharyx sp., obtained from pipeline seawater pumped up from a depth of 384 m in Toyama Bay. Two living worms collected from the nylon mesh attached to the pump outlet produced greenish light when disturbed. They were identified as Tharyx sp. (Cirratulidae) by morphological examination and DNA sequencing. Bioluminescence of cirratulid worms is not widely reported and, to our knowledge, this is the first report of bioluminescence in the genus Tharyx.

No abstract

Pontodrilus litoralis is a cosmopolitan littoral earthworm known to exhibit bioluminescence. Recently, a congeneric species Pontodrilus longissimus from Thailand was described. These species are sympatric but their burrowing depths on Thai beaches are different. In this study, we examined the in vivo and in vitro bioluminescence properties of P. longissimus and P. litoralis. Mechanical stimulation induced in vivo luminescence in P. litoralis, as reported previously, but not in P. longissimus. In vitro cross-reaction tests between these species revealed the absence of luciferin and luciferase activities in P. longissimus. P. litoralis had strong fluorescence in a coelomic fluid that matches to the spectral maximum of its bioluminescence, but P. longissimus did not. These results suggest that P. longissimus does not have luminescence ability due to the lack of all bioluminescent components, luciferin, luciferase, and light emitter, despite its close relationship to the luminous P. litoralis. The presence of both luminous and non-luminous species in a single genus is uncommon, and our present findings will shed insight on the possible functions of bioluminescence in the earthworm, such as avoiding predation by littoral earwigs.