Violet Tunicate

Violet Tunicate, or botrylloides violaceus, is a colonial tunicate which forms irregularly-shaped colonies usually of a solid colour of either cream, yellow or purple. Zooids (individuals) are about 2 to 4 mm in width and stand upright within the colony usually forming a series of rows.

This species grows on a variety of man-made substrates (docks, boat hulls, buoys, ropes, etc.) and natural hard substrates in the shallow subtidal zone, mainly in protected areas. Eggs are fertilized within the matrix of the colony and larvae are only free-swimming for a few hours. Like other colonial tunicate species violet tunicate can produce new colonies from fragments.


(Photo credit: D. Mouland, DFA)

Means of introduction

Since the larval period of Violet Tunicate is short it is not likely spread through ballast water, but it is thought to be spread mainly through hull fouling.

Management of the species

Fish and shellfish harvesters should avoid transferring harvested shellfish and fishing gear to other areas. Gear should be thoroughly dried before transfer. Boat hulls should be inspected and, if necessary, manually cleaned. Any organisms removed from boat hulls or gear should be disposed of on land. If pressure washing is necessary to remove colonial tunicates from equipment only do so on land and make sure the out-flow does not go into the sea as colonies can re-grow from small fragments. Report sightings by using the contact information on the main AIS page.

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