This article is not about flying ocean plants. Plankton, a diverse group of organisms, comes in two main categories: phytoplankton and zooplankton. In a fascinating discovery that challenges our understanding of marine ecosystems, scientists discovered that tiny crustaceans, zooplankton called copepods, possess a remarkable escape mechanism: they can leap out of the water and into the air to evade predatory fish[1][2].
Aerial Acrobatics of the Microscopic World
Copepods, particularly those in the family Pontellidae, have been observed breaking through the ocean’s surface and propelling themselves through the air, traveling up to 60 times their body length[1]. This behavior, long overlooked by researchers, provides these minuscule creatures with a significant survival advantage in their perilous surface-dwelling habitat.
The Paradox of Pontellid Abundance
Dr. Brad Gemmell and his team at the University of Texas in Austin were intrigued by the seemingly paradoxical abundance of Pontellid copepods. These brightly colored, relatively large (3mm) crustaceans live in the uppermost layers of the ocean, where they should be easy targets for predatory fish[8]. Unlike other copepod species that migrate to deeper, darker waters during the day, Pontellids remain near the surface, their vibrant blue or green coloration offering protection from UV radiation but making them conspicuous to predators[8].
The Physics of Microscopic Flight
The researchers discovered that copepods use up to 39% of their kinetic energy to break through the water’s surface tension, a feat that requires precise timing and tremendous power relative to their size[1][3]. Once airborne, copepods encounter much less resistance, allowing them to travel significantly further than they could underwater. This aerial escape not only takes them out of immediate danger but also confuses predators about where they will land[8].
Evolutionary Trade-offs
This escape mechanism comes at a considerable energetic cost. Copepods must balance the risk of predation against the energy expenditure of their aerial leaps[8]. This trade-off has likely shaped their evolution, resulting in escape behaviors that are both effective and efficient.
Implications for Marine Ecology
The discovery of this behavior has significant implications for our understanding of marine food webs. Copepods are a crucial food source for many commercially important fish species, including cod, pollock, and whiting[8]. Their ability to escape so effectively may partly explain their abundance and ecological success despite their vulnerable position in the food chain.
This research highlights the importance of studying the air-water interface, a unique and often overlooked habitat in marine ecosystems. It also demonstrates how even the smallest organisms can evolve sophisticated strategies to survive in challenging environments.
Read More
[1] https://www.practicalfishkeeping.co.uk/fishkeeping-news/copepods-take-to-the-air-to-avoid-predators/
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3367780/
[3] https://pubmed.ncbi.nlm.nih.gov/29191859/
[4] https://www.oceanlifecentre.dk/news/nyhed?id=b2d38ca9-df5f-4c7d-b4c2-320cd3c16890
[5] https://www.int-res.com/articles/meps2002/235/m235p135.pdf
[6] https://academic.oup.com/icb/article/53/5/821/731962
[7] https://www.bbc.co.uk/news/science-environment-17430640
[8] https://www.bbc.com/news/science-environment-17430640
