Size variation and geographical distribution of the luminous earthworm Pontodrilus litoralis (Grube, 1855) (Clitellata, Megascolecidae) in Southeast Asia and Japan
Abstract:The luminous earthworm Pontodriluslitoralis (Grube, 1855) occurs in a very wide range of subtropical and tropical coastal areas. Morphometrics on size variation (number of segments, body length and diameter) and genetic analysis using the mitochondrial cytochrome c oxidase subunit 1 (COI) gene sequence were conducted on 14 populations of P.litoralis from Southeast Asia and Japan. Statistical inference on morphometric data revealed significantly different size variations in the body length and diameter among th… Show more
“…A British television program 26 presented by David Attenborough showed that the French luminous earthworm Avelona ligra glowed when attacked by the carabid beetle, but the beetle consumed the luminescent worm without any hesitation. We suggest that the absence of bioluminescence in P. longissimus may be associated with its presence in habitats with low predation pressure, whereas P. litoralis acquired a bioluminescent property during evolution that enabled it live on the surface of the beach, which is rich in nutrition and food sources 3 , 27 as well as potential predators. Figure 4 ( A ) The microhabitat of Pontodrilus litoralis from Aichi Prefecture, Japan.…”
Section: Discussionmentioning
confidence: 97%
“…The earthworm genus Pontodrilus Perrier, 1874, displays various unique characteristics. The littoral earthworm P. litoralis (Grube, 1855) is distributed on the tropical and subtropical coasts of the Atlantic, Indian and Pacific Oceans 1 – 3 and is known to be bioluminescent 4 – 7 . The luminescent system of P. litoralis has been shown to be a luciferin-luciferase type reaction triggered by hydrogen peroxide, with a fluorescence compound acting as a light emitter 7 , although the chemical structure of the luciferin remains uncertain and the luciferase gene has not been determined.…”
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.
“…A British television program 26 presented by David Attenborough showed that the French luminous earthworm Avelona ligra glowed when attacked by the carabid beetle, but the beetle consumed the luminescent worm without any hesitation. We suggest that the absence of bioluminescence in P. longissimus may be associated with its presence in habitats with low predation pressure, whereas P. litoralis acquired a bioluminescent property during evolution that enabled it live on the surface of the beach, which is rich in nutrition and food sources 3 , 27 as well as potential predators. Figure 4 ( A ) The microhabitat of Pontodrilus litoralis from Aichi Prefecture, Japan.…”
Section: Discussionmentioning
confidence: 97%
“…The earthworm genus Pontodrilus Perrier, 1874, displays various unique characteristics. The littoral earthworm P. litoralis (Grube, 1855) is distributed on the tropical and subtropical coasts of the Atlantic, Indian and Pacific Oceans 1 – 3 and is known to be bioluminescent 4 – 7 . The luminescent system of P. litoralis has been shown to be a luciferin-luciferase type reaction triggered by hydrogen peroxide, with a fluorescence compound acting as a light emitter 7 , although the chemical structure of the luciferin remains uncertain and the luciferase gene has not been determined.…”
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.
“…A British television program [26] presented by David Attenborough showed that the French luminous earthworm Avelona ligra glowed when attacked by the carabid beetle, but the beetle consumed the luminescent worm without any hesitation. We consider that the absence of bioluminescence in P. longissimus may correlate with the habitats with low-predation pressure, whereas P. litoralis acquired a bioluminescence property during evolution that enables it to enter the surface environment of the beach, which is rich in nutrition and food sources [3,27] as well as in potential predators.…”
Section: Discussionmentioning
confidence: 99%
“…The littoral earthworm P. litoralis was collected at a sandy region of one of the following beaches [3,8]: Wonnapa beach, Amphoe Mueang Chon Buri, Chonburi, Thailand (13°15'55.6"N 100°55'29.3"E), Kowa beach, Chita, Aichi prefecture, Japan (34°46'23.3"N 136°54'52.7"E) and Kira Waikiki Beach, Nishio, Aichi prefecture, Japan (34°46'55.2"N 137°05'48.3"E). P. longissimus was collected from Tambon Muang Klang, Amphoe Kaper, Ranong, Thailand (9°37'26.7"N 98°28'08.6"E).…”
Section: Specimens and Species Identi Cationmentioning
confidence: 99%
“…The earthworm genus Pontodrilus Perrier, 1874 displays various unique characteristics. The littoral earthworm P. litoralis (Grube, 1855) distributes in the tropical and sub-tropical coasts of the Atlantic, Indian and Paci c Oceans [1][2][3], and is known to be bioluminescent [4][5][6][7]. The luminescent system of P. litoralis has been shown to be a luciferin-luciferase type reaction triggered by hydrogen peroxide, with a uorescence compound acting as a light emitter [7], although the chemical structure of the luciferin remains uncertain and the luciferase gene has not been determined.…”
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.
The cosmopolitan littoral earthworm Pontodrilus litoralis is distributed in tropical and sub-tropical coastal habitats, whereas P. longissimus is reported only in the Thai-Malay coastal line. In the present study, we examined the difference in salinity effect on the survival rate, wet weight (hereafter weight) change, behaviour, and osmolality of these two Pontodrilus species. A 28 d exposure to varying salinity concentration (0–50 ppt) revealed that P. litoralis is able to survive over a wide salinity range than P. longissimus, with the latter species exhibiting a low survival rate over the same salinity range. During short-term exposure (0–96 h) to a salinity of less than 30 ppt, P. litoralis exhibited weight gain and this was significant in the first 12 h of exposure. However, P. longissimus gained weight when exposed to salinity at under 10 ppt in the first 72 h of exposure. The two species of Pontodrilus behaved differently when exposed to different salinities. The coelomic fluid osmolarity of Pontodrilus was related to the exposure medium and was mostly maintained as hyperosmotic to the external medium over the range of salinities tested. This study shows how two different species of the littoral earthworm genus Pontodrilus respond to a change in salinity, which may explain their dispersal pattern and shape their distribution pattern throughout Southeast Asia.
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