When poked, tunicates will squirt water. Hence, their nickname: sea squirts. But as cute as that sounds, these slimy, gelatinous sea creatures are anything but cuddly.
“They can be divided into two categories,” says Claudio DiBacco, a research scientist with Canada’s Fisheries and Oceans Canada. “Those that have been around since the latter part of the 19th century, they don’t harm the environment. It’s the newcomers that have arrived in the last few decades that are the troublemakers,” he says.
How sea squirts arrive and spread in a new area is no mystery. Often, they hitch rides in the ballast water used to weigh down ships without cargo. “The larvae are invisible and float with the ocean currents. They’re onboarded with a ship’s ballast water, and when it discharges in a new location, so does the tunicate,” says Boris Worm, a marine ecologist at Dalhousie University’s Ocean Frontier Institute. “It is almost impossible to keep them from spreading.”
Sea squirts are tiny (species range from 6-10 inches long) and have cute nicknames such as Compound Sea Squirt, Golden Star and Pancake Batter. But, despite their small stature and fun names, these invaders sucker themselves like barnacles to any hard surface, natural or manmade, singularly or in massive colonies. And they are heavier than they look. Made up of organs, sea squirts are 95 percent water; an oyster cage weighing five pounds can easily exceed 75 lbs. when attacked by colonized tunicates.
Colton D’Eon is a self-described sea farmer and chief operating officer for D’Eon Oyster Company in Yarmouth, NS. He remembers the first time his oyster farm was hit with a tunicate infestation. “We weren’t prepared for how heavy they were, and lines snapped and we lost
Read more on modernfarmer.com