June 20, 2025
University of Tsukuba
Keio University
After attaching to a surface such as a rock, sea squirt larvae begin metamorphosis after several tens of minutes, transforming from larvae into adults. It has been revealed that sea squirts measure the time from attachment to the start of metamorphosis by the accumulation of a substance called cyclic adenosine monophosphate (cAMP), which is responsible for intracellular signaling.
Sea squirts undergo metamorphosis from actively swimming, tadpole-shaped larvae to sessile, immobile adults. This metamorphosis is triggered by the larva attaching to a surface such as a rock, but it is known to begin several tens of minutes after attachment. This is thought to be a mechanism to ensure firm attachment, but how sea squirt larvae measure the necessary time was not understood.
This study reveals that sea squirt metamorphosis is initiated by the accumulation of the chemical substance cyclic adenosine monophosphate (cAMP), which is responsible for intracellular signaling, and that the time from attachment to the start of metamorphosis is the time required for a sufficient amount of this cAMP to accumulate. We also found that a complex mechanism is at work: cAMP does not accumulate immediately after attachment; instead, its level first decreases and then begins to rise. This suggests that they do not begin metamorphosis immediately upon attachment but are instead reliably measuring time.
The ability of organisms to measure time is essential for triggering biological phenomena at the appropriate time, but many of the mechanisms for this remain unelucidated. This research provides hints for inferring time-measurement mechanisms in other organisms and is expected to be useful for developing technologies to improve aquaculture methods by manipulating the timing of biological phenomena and to prevent the attachment of marine organisms.
For the full press release, please see below.