 On a field sampling trip, OIST scientist Aki Masunaga is on the hunt for tiny titans. Today we are looking for something called a larvacean, and they are planktonic tunicates, so they are floating around in the water column. Tunicates are better known as sea squirts. The larger species are rooted on the spot, filter feeding from the water, but larvaceans are much smaller and take their filter feeding on the move. Even though they look very different from most vertebrates, in terms of evolution, they are closely related to vertebrates. The animals live inside of a bubble-like structure called the house, which they use to filter feed small organisms like bacteria and microalgae in the water. And when the house gets clogged by bigger particles, they discard it and build a new one. And they can do this throughout the day and they can build several houses per day. The discarded house floats slowly down in the water, becoming part of what's known as marine snow, a major part of the deep ocean food web. There are so many of them and they are constantly filter feeding, so the combined effect that they have on the ocean is significant. At OIST, one larvacean species has become part of a big science initiative. The university is one of only four in the world to breed oikoplura dioica in captivity. Because it turns out that oikoplura, oics for short, have a lot of special features that make them fascinating to study.