Ikeda taenioides

Ikeda taenioides
Scientific classification
Kingdom:	Animalia
Phylum:	Annelida
Class:	Polychaeta
Subclass:	Echiura
Family:	Ikedidae
Genus:	Ikeda
Species:	I. taenioides
Binomial name
	Ikeda taenioides; (Ikeda, 1904)[1]
Synonyms[1]
	Thalassema taenioides Ikeda, 1904;

Ikeda taenioides is a species of spoon worm in the family Ikedidae. It is native to the northern Pacific Ocean where it is found in the subtidal waters around Japan.

Taxonomy

This spoon worm was first described by the Japanese zoologist I. Ikeda in 1904 as Thalassema taenioides, the type locality being Misaki, Sagami Bay, in Honshu, Japan. Examination of the musculature of the body wall led to the observation that the longitudinal muscle layer lay outside both the circular layer and the inner oblique layer, and as this was at odds with all other members of the subclass Echiura, it warranted the creation of a new order. However, examination of the original material by Teruaki Nishikawa in 2002, showed that the longitudinal muscle layer was in fact between the circular layer and the oblique layer, as in all other echurians, throwing the taxonomy of the species into doubt. Nishikawa advocates that the family Ikedidae be regarded as a junior synonym of Echiuridae.[2]

Description

Ikeda taenioides is the largest spoon worm in the world, its proboscis being visible protruding from its burrow while the trunk remains hidden.[3] The trunk can be 40 cm (16 in) long and the proboscis 150 cm (60 in).[4]

Ecology

Ikeda taenioides lives in soft sediment where it digs itself a burrow, often descending to 70 to 90 cm (28 to 35 in) below the sand surface. The proboscis is protruded through the burrow entrance to feed, and a number of these probosces were observed by researchers in 2011, some eight months after a tsunami had devastated the seabed habitat.[3] The tsunami had destroyed the seagrass beds, the heart urchins and the Venus clams in the community; the researchers thought the spoon worms had survived the turbulent conditions because of the depths of their burrows.[3]

References

Tanaka, Masaatsu (2017). "Ikeda taenioides (Ikeda, 1904)". WoRMS. World Register of Marine Species. Retrieved 19 February 2019.
Nishikawa, Teruaki (2002). "Comments on the taxonomic status of Ikeda taenioides with some amendments in the classification of the phylum Echiura". Zoological Science. 19 (10): 1175–1180. doi:10.2108/zsj.19.1175.
Goto, Ryutaro; Sakamoto, Shingo; Hayakawa, Jun; Seike, Koji (2017). "Underwater observations of the giant spoon worm Ikeda taenioides (Annelida: Echiura: Ikedidae) in a subtidal soft-bottom environment in northeastern Japan, which survived tsunamis of the 2011 off the Pacific Coast of Tohoku Earthquake". Journal of Oceanography. 73 (1): 103–113. doi:10.1007/s10872-016-0380-2.
Williamson, D. (2013). The Origins of Larvae. Springer Science & Business Media. p. 63. ISBN 978-94-017-0357-4.

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[WoRMS-1] Tanaka, Masaatsu (2017). "Ikeda taenioides (Ikeda, 1904)". WoRMS. World Register of Marine Species. Retrieved 19 February 2019.

[2] Nishikawa, Teruaki (2002). "Comments on the taxonomic status of Ikeda taenioides with some amendments in the classification of the phylum Echiura". Zoological Science. 19 (10): 1175–1180. doi:10.2108/zsj.19.1175.

[Goto-3] Goto, Ryutaro; Sakamoto, Shingo; Hayakawa, Jun; Seike, Koji (2017). "Underwater observations of the giant spoon worm Ikeda taenioides (Annelida: Echiura: Ikedidae) in a subtidal soft-bottom environment in northeastern Japan, which survived tsunamis of the 2011 off the Pacific Coast of Tohoku Earthquake". Journal of Oceanography. 73 (1): 103–113. doi:10.1007/s10872-016-0380-2.

[4] Williamson, D. (2013). The Origins of Larvae. Springer Science & Business Media. p. 63. ISBN 978-94-017-0357-4.