Focus on Clavelina

Clavelina lepadiformis / Lightbulb ascidian, a type of sea squirt or ascidian, is one of the prettiest of the marine pests.

Photo supplied by Northland Regional Council

It is established in pockets of the country, a long-time resident at Nelson Marina and more recently found itself at home in some areas of the North Island, including the Marsden Cove and the Gulf Harbour areas. 

For boat owners and haulout operators, it’s raising some eyebrows because it will grow even on clean boats and any other surface, but can fall off or dislodge with not much encouragement needed at all, including at the point the boat is hauled out of the water.

There are two exotic species of Clavelina currently known in New Zealand. Clavelina oblonga is currently only known to be in the Port Fitzroy area at Aotea Great Barrier Island, and Clavelina lepadiformis. They are both gelatinous, soft to the touch and have a translucent appearance. They are solitary organisms but tend to live in dense colonies and they reproduce asexually - which means they create copies of themselves even from small fragments. They are very efficient filter feeders which means they can take nutrients away from native species - and as they live in dense colonies, they crowd them out too. The lightbulb appearance is the true giveaway to distinguish between the two species, and that seems to be sometimes yellow and through to a pretty pinkish colour.

See more photos of the Clavelina species in our marine pest ID guide: