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.

[2] Ikeda taenioides is the largest spoon worm in the world, its proboscis being visible protruding from its burrow while the trunk remains hidden.

[4] 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.