After driving up to Maine for a friend’s wedding, we decided to take some time to explore the coast. We stopped at Wolfe’s Neck Woods State Park, where we found the following cluster of insects floating on the surface of a tidal pool.
These are Collembola or springtails. According to Frans Janssens, laboratory associate of the Department of Biology at the University of Antwerp, Belgium, this species is likely Anurida maritima (Neanuridae: Pseudachorutinae), a common intertidal species.
This species can commonly be found on the surface of the water in littoral or intertidal zones, forming rafts like the one pictured above. These Collembola are scavengers, but likely feed on diatoms and other plankton in the water as well.
According to Frans Janssens, the rafting behavior is a “side-effect of the meniscus that is formed by the water surface film”. When Collembola aggregate and float together, they create a depression or “pit” in the surface of the water. The more Collembola that gather, the deeper this pit in the water’s surface becomes, and the harder it is for them to get away from the rest of the group. However, this is not necessarily a problem; being part of such a large aggregation could offer a valuable opportunity to find mates and breed.
The rafting behavior could also serve as a means of dispersal. The tides and current could carry clusters of Collembola up and down the coast, or even to oceanic islands (Hawes et al 2008). This rafting behavior may have allowed Collembola to reach and colonize the Galapagos Islands (Coulson et al 2002).
Check out a video of this cluster of Collembola below!
References:
Coulson, S. J., Hodkinson, I. D., Webb, N. R., & Harrison, J. A. (2002). Survival of terrestrial soil‐dwelling arthropods on and in seawater: implications for trans‐oceanic dispersal. Functional Ecology, 16(3), 353-356.
Hawes, T. C., Worland, M. R., Bale, J. S., & Convey, P. (2008). Rafting in Antarctic collembola. Journal of Zoology, 274(1), 44-50.
Special thanks to Frans Janssens for his help and expertise!
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