Asymmetron inferum

Asymmetron inferum
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Subphylum:	Cephalochordata
Class:	Leptocardii
Family:	Branchiostomatidae
Genus:	Asymmetron
Species:	A. inferum
Binomial name
	Asymmetron inferum; Nishikawa, 2004

Last updated January 13, 2026

Asymmetron inferum, the whale-fall lancelet, is a species of lancelet that is native to reducing habitats of the Northwest Pacific Ocean of Japan.^[1]^[2]A. inferum is unique among lancelets for seemingly preferring the anaerobic conditions of reducing habitats.^[1]^[2]

Taxonomy

The date of divergence between Asymmetron inferum and its sister group, the Asymmetron lucayanum complex, is estimated to be between 115 and 97 million years ago, during the middle Cretaceous. Dating to well before the evolution of whales, it is likely this species relied on carcass-falls of marine reptiles and other vertebrates^[3].

References

1 2 3 Nishikawa, Teruaki (2004-11-01). "A New Deep-water Lancelet (Cephalochordata) from off Cape Nomamisaki, SW Japan, with a Proposal of the Revised System Recovering the Genus Asymmetron". Zoological Science. 21 (11): 1131–1136. Bibcode:2004ZooS...21.1131N. doi:10.2108/zsj.21.1131. ISSN 0289-0003. PMID 15572865.
1 2 Nishikawa, Teruaki; Komatsu, Hironori; Kameda, Yuichi; Tani, Kenichiro (2017). "A New Find of the Whale-fall Lancelet Asymmetron inferum (Cephalochordata) near a Hydrothermal Vent at Oomuro-dashi Submarine Volcano in the Izu Islands, Pacific Coast of Japan, as a Possible Case to Prove the Stepping-stone Hypothesis". Species Diversity. 22 (1): 69–72. doi:10.12782/sd.22_69.
↑ Kon, Takeshi; Nohara, Masahiro; Yamanoue, Yusuke; Fujiwara, Yoshihiro; Nishida, Mutsumi; Nishikawa, Teruaki (2007-07-31). "Phylogenetic position of a whale-fall lancelet (Cephalochordata) inferred from whole mitochondrial genome sequences". BMC Evolutionary Biology. 7 (1): 127. Bibcode:2007BMCEE...7..127K. doi: 10.1186/1471-2148-7-127 . ISSN 1471-2148. PMC 2034537 . PMID 17663797.

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[:0-1] 1 2 3 Nishikawa, Teruaki (2004-11-01). "A New Deep-water Lancelet (Cephalochordata) from off Cape Nomamisaki, SW Japan, with a Proposal of the Revised System Recovering the Genus Asymmetron". Zoological Science. 21 (11): 1131–1136. Bibcode:2004ZooS...21.1131N. doi:10.2108/zsj.21.1131. ISSN 0289-0003. PMID 15572865.

[:1-2] 1 2 Nishikawa, Teruaki; Komatsu, Hironori; Kameda, Yuichi; Tani, Kenichiro (2017). "A New Find of the Whale-fall Lancelet Asymmetron inferum (Cephalochordata) near a Hydrothermal Vent at Oomuro-dashi Submarine Volcano in the Izu Islands, Pacific Coast of Japan, as a Possible Case to Prove the Stepping-stone Hypothesis". Species Diversity. 22 (1): 69–72. doi:10.12782/sd.22_69.

[3] Kon, Takeshi; Nohara, Masahiro; Yamanoue, Yusuke; Fujiwara, Yoshihiro; Nishida, Mutsumi; Nishikawa, Teruaki (2007-07-31). "Phylogenetic position of a whale-fall lancelet (Cephalochordata) inferred from whole mitochondrial genome sequences". BMC Evolutionary Biology. 7 (1): 127. Bibcode:2007BMCEE...7..127K. doi: 10.1186/1471-2148-7-127 . ISSN 1471-2148. PMC 2034537 . PMID 17663797.

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