For the past decade, I have been thinking about publishing a paper that addresses the question of why the bootlace worm evolved to become so extraordinarily long. This species is listed in the Guinness World Records as the longest animal, with a specimen recorded to have reached 55m in length after being washed ashore following a storm in Scotland in 1864. Although no individuals of such extreme length have been documented since then, specimens measuring 5–10m are still found relatively commonly. In contrast, the average body length of the approximately 1,300 known species of ribbon worms is at most about 10cm, leaving little doubt that this species is exceptionally longer than other members of the phylum. I hope to be able to discuss the evolution of reproductive strategies based on a phylogenetic analysis of the bootlace worm and its close relatives.

Since 2023, I have been serving as an editor for a planned textbook that brings together the collective expertise of Japanese phylogenetic taxonomists, scheduled for publication in 2026. In this field, the use of nucleotide sequence data has become widespread since the early 2000s, greatly improving reproducibility and objectivity compared with traditional analyses based on morphological characters, which often allow considerable subjective interpretation. As a result, it has become relatively straightforward to infer reliable phylogenetic trees. A book series under the same title was published between 1961 and 1999; the forthcoming volume aims to update the knowledge in this field, which has advanced dramatically over the past 25 years. More than 70 specialists from Japan and abroad are expected to contribute overview chapters covering all 34 animal phyla.

Because my senior and junior lab mates during my graduate years were all highly accomplished, I carried a persistent sense of inferiority. In what might be called the “paper race,” I was always trailing them, and I never imagined that someone like me would eventually secure a teaching position like the one I hold today. After earning my Ph.D. degree, there was a period of about one year during which I made a living as a part-time lecturer at technical/vocational schools in the city. During a class at one such school, I once explained to the students that my own position was unstable. One of them responded by saying, “I’m sure you will become a researcher in the future.” Because I was going through a mentally difficult time, that unexpected expression of kindness left a deep impression on me, and it is something I will never forget.