Marine scientists have shared a surprisingly endearing video of an eastern oyster larva feeding on algae.\u00a0<\/p>\n
The video is important for more than just its cute value<\/a>. It has helped scientists highlight the importance of gravity in the feeding process of these tiny creatures \u2013 which, it turns out, may present issues for oysters in the future.<\/p>\n Eastern oyster larvae are miniscule. An individual usually measures between 100 and 300 micrometres long (that\u2019s 0.1 to 0.3mm). For context, an individual grain of sea salt is typically between 0.22mm and 0.93mm.<\/p>\n Because these animals are so small, the scientists had to develop a special imaging technique to film the feeding larvae without disturbing them. In the footage \u2013 which has been slowed down by ten times \u2013 an adorable little oyster larva drifts through the water, fluttering its hair-like cilia to capture floating particles of\u00a0algae<\/a>.<\/p>\n Researchers long thought that these larvae created currents to draw food towards them using the drag from their swimming movement.\u00a0<\/p>\n By tracking the tiny particles in the water, the video shows that they actually bring food towards their hungry little mouths using gravity. The larva\u2019s shell is heavier than the seawater around it and so produces a current that brings the food straight to it, like an ocean-based meal delivery service. The findings are published in\u00a0Physical Review Fluids<\/a>.<\/p>\n A high-speed video of eastern oyster larva swimming in seawater seeded with algae. The original video was taken at 2,000 frames per second, but is slowed down 10x in this clip. Credit: video by Houshuo Jiang, Woods Hole Oceanographic Institution<\/p>\n \u201cThanks to high-speed imaging, we now see that gravity is essential for their feeding,\u201d says the study\u2019s author Houshuo Jiang, a senior scientist at the Woods Hole Oceanographic Institution (WHOI<\/a>).<\/p>\n \u201cThis tells us that the shell is doing more than just protecting the animal,\u201d says Jiang. \u201cIt is actually helping the larva feed. That means anything that changes the shell could also change how the larva gets its food.\u201d<\/p>\n This is concerning because the ocean is becoming increasingly acidic.\u00a0Ocean acidification<\/a>\u00a0makes it harder for animals with hard calcium carbonate exteriors \u2013 such as\u00a0oysters<\/a>,\u00a0mussels<\/a>\u00a0and\u00a0corals<\/a>\u00a0\u2013 to create and maintain their structures.\u00a0<\/p>\n If an oyster larva was unable to create as strong a shell, it might become less dense and struggle to feed using these gravity-driven currents.\u00a0<\/p>\n \u201cUltimately, this could help us better understand what determines whether oyster larvae survive and become part of the adult population,\u201d says Jiang. \u201cIf environmental stressors affect both shell formation and feeding, we need to understand those effects to better predict how oyster populations will respond to a changing ocean.\u201d<\/p>\n