Amyloodinium ocellatum, also known as marine velvet, is a species of microbial parasitic dinoflagellates of the Amyloodinium genus. Currently, A. ocellatum has been the only species discovered in the Amyloodinium genus and has been found in various aquatic regions around the world in both tropical and temperate habitats. A. ocellatum is a temperature dependent microbe which can live in both salt and freshwater. A. ocellatum is also an obligate parasitic microbe, depending on marine animals to survive and complete their life cycles. The life cycle of A. ocellatum follows a parasitic growth model, maturing from a trophont to a tomont, before growing into a dinospore. First analyzed in the 1930s, A. ocellatum has since been identified as a major agent of disease among marine life.
The life cycle of Amyloodinium ocellatum can be broken down into three main stages. In their adult stage, the parasites are known as trophonts and are able to feed on adult fish. In the second stage, the parasites develop into tomonts, detach from the host, and begin developing dinospores. In this last stage, the microbes are known as dinospores, free floating agents looking for another host to infect. In all three stages, A. ocellatum remains infectious, allowing the microbe to stay deadly throughout its entire life cycle.
Disease in marine life
Amyloodinium ocellatum is able to infect the majority of both salt and freshwater fish. The disease transmitted by A. ocellatum is commonly referred to amyloodiniosis, marine velvet, or velvet disease. Fish that have been infected with A. ocellatum have a powdered appearance. Other symptoms include a loss of coordination and sporadic gasping. A. ocellatum has specialized structures which are used to penetrate deep into the host tissue. This process causes significant tissue damage at the attachment site. A. ocellatum is able to transfer and spread quickly in closed, dense populations. Thus, the microbe poses a significant threat to many marine industries and farms.
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- Francis-Floyd, Ruth, and Maxine R. Floyd. Amyloodinium ocellatum, an important parasite of cultured marine fish. Southern Regional Aquaculture Center, 2011.