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The Vase Tunicate
Kingdom: Animalia
Phylum: Chordata
Subphylum: Tunicata (Urochordata)
Class: Ascidiacea
Order: Enterogona
Suborder: Phlebobranchia
Family: Cionidae
Genus: Ciona
Species: C. intestinalis
The Vase Tunicate (Ciona intestinalis) The scientific name of the vase tunicate means "pillar of intestines" in Latin. This species lies in the Phylum Chordata due to its larval stage. The larval stage is, in some ways, very similar to vertebrates. Studies have shown that, to our knowledge, these sea squirts are closest invertebrate relatives to vertebrates. The vase tunicate is a very invasive, solitary tunicate.
Morphology of The Vase Tunicate: The vase tunicate is in the shape of a cylinder and it is a translucent white. They grow to approximately six inches. They attach to essentially any substrate that is hard, whether it is man-made or natural. They can often clump in large groups, which can lead to bio fouling issues.
The picture on the left portrays both of the life stages of ciona intestinalis. In this picture (a) shows the adult stage of the sea squirt, while (b) and (c)
present in the larvae. These structures are lost when the larvae move into the adult stage. They have a postanal tail. The larvae also have pharygeal slits that form the pharygeal basket (or the branchial sac show in the picture on the right) in adults. Tunicates do not feed when they are in the larvae form. They do, however, live off of stored yolk. Larvae are mobile and can travel. They travel until they find a suitable environment, and then they cement themselves on a rock. As soon as it attaches, it undergoes metamorphosis.
The adult morphology is depicted in the picture on the right. The adult tunicate is surrounded by a "tunic" exoskeleton. The tunicate has an buccal siphon, which has in incurrent flow of water, and an atrial siphon, which has an excurrent flow of water. The tunicate has an endostyle the secretes mucus. This mucus can aid in the capture of food. As water flows into the buccal siphon phytoplankton is captured is captured and digested. The water flows out of the atrial siphon. Not only is a constant flow of water important to obtain a sufficient amount of food, but it also helps maintain the shape of the organism. The Vase Tunicate can often siphon hundreds of liters of water a day. The heart, stomach, intestines, and ovary are all located at the bottom of the organism. Waste from the digestive system exits from the atrial siphon with the help of the rectum.
This species is hermaphroditic. It releases both sperm and egg into the water. However, these creatures are self-sterile, because the male and female parts don't mature at the same time and the sperm and eggs can not be released at the same time. This means that they require an additional mate to copulate.
Location of the Vase Tunicate: ciona intestinalis is spread throughout the world. It has been found in the eastern United State, on the east coast of Canada, and most recently large amounts have been found in Nova Scotia and Prince Edward Island. It has also been found as far North as Newfoundland. It can, however, be found on every continent except Antarctica. They are found mostly near rocky shores. They also infest most man-made structures like piers. They can also be found on the hulls of boats or on buoys. Infestations in mussel farms located around Prince Edward Island are severe and have been used to study the behaviors of this extremely invasive, solitary tunicate.
Ecology of the Vase Tunicate: ciona intestinalis does not benefit humans in any way. It serves as a nuisance by inhabiting boats or other man-made structures. However, the vase tunicate greatly impacts mussel farms. This very invasive species live on these mussels and the equipment that is used to harvest these mussels. Since mussels are also filter feeders they need to compete with the tunicates, but the tunicates can easily overwhelm
show us the larval stage. The larval stage landed this species in the Phylum Chordata. This is due to the notochord and the nerve cord that is
the mussels by how quickly they can reproduce and spread. This species infest mussel farms which increases the labor and costs of these farms. Because of this these tunicates are now recognized as a very important pest that is capable of vast economic loss.
These tunicates can cause extra costs and labors to these farms. When the tunicates live on the mussels, then it requires extra labor by the farms to remove the tunicates from the mussels. There are also addition transport and waste disposal fees that are associated with removing the tunicates. On top of this, it can also cause losses to prior to harvest. "The accumulated weight of fouling tunicates breaks the mussels' byssal thread attachment, causing them to fall to the bottom where they lose any commercial value" (Comeau, 2015).
This industry is constantly trying to find a strategy to control or stop these infestations. Mussel farms around Prince Edward Island apply pressurize ambient seawater to remove the vase tunicate, however this is fairly ineffective and the tunicates quickly recolonize. New treatments or strategies have not yet been discovered, but they being actively explored.
Fun Fact about Tunicates: Tunicates belong to one of the three subphyla of the phylum Chordata. The three subphyla are: Vertebrata (which contain the vertebrates), Tunicata (containing the tunicates), and Cephalochordata (which contain lancelets). The tunicates are primarily placed in the phylum chordata due to the fact that their larvae stage contains all four defining characteristics of a chordate, even if there adult stage does not.
References:
Abbott, D.P., Newberry, A.T., 1980. Urochordata: the tunicates. In: Morris, R.H., Abbott, D.P., Haderlie, E.C. (Eds.), Intertidal Invertebrates of California. Stanford University Press, Stanford, California, pp. 177–226.
Arens, C.J., Paetzold, S.C., Ramsay, A., Davidson, J., 2011. Pressurized seawater as an antifouling treatment against the colonial tunicates Botrylloides violaceus and Botryllus schlosseri in mussel aquaculture. Aquat. Invasions 6, 465–476.
Comeau, Luc A., Ramon Filgueira, Thomas Guyondet, and Remi Sonier. "The Impact of Invasive Tunicates on the Demand for Phytoplankton in Longline Mussel Farms." Elsevier (2015): 95-105. 21 Feb. 2015. Web. 31 Oct. 2016.
Gill, K., 2008. Tunicate impact and control options on oyster culture systems. PEI Department of Fisheries, Aquaculture and Rural Development Technical Report, August 2008 (33 pp.).
Locke, A., Hanson, J.M., Ellis, K.M., Thompson, J., Rochette, R., 2007. Invasion of the southern Gulf of St. Lawrence by the clubbed tunicate (Styela clava Herdman): potential mechanisms for invasions of Prince Edward Island estuaries. J. Exp. Mar. Biol. Ecol. 342, 69–77.
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