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Trididemnum sp.

Georgina Walker (2013)



Fact Sheet



Physical Description


Life History & Behaviour

Anatomy & Physiology

Evolution & Systematics

Biogeographic Distribution

Conservation & Threats

References & Links


As the species of Trididemnum was not identified and life histories of known species within the genus are very diverse only general information on the life history of ascidians will be given here. 

Reproduction & Development

The majority of ascidians are hermaphrodites (Lemaire et al, 2008). Solitary species reproduce sexually, typically via cross-fertilisation, while colonial species reproduce both sexually and asexually. Reproductive strategies amongst ascidian species are diverse. Studies on the colonial ascidian B. schlosseri have shown that even amongst individual colonies sperm and egg production and reproductive cycle duration is highly variable (Yund et al, 1997). Seasonality of sexual reproduction has been recognised in some species of Trididemnum while others spawn year round (Hirose et al, 2007). Asexual growth in colonial ascidians occurs by budding, however this mode of reproduction is also variable amongst species. 

Most colonial ascidians are viviparous, in that they release tadpole larvae rather than eggs, and have lecithotrophic development (short lived, yolk-feeding larvae). Tadpole larvae have all the key characteristics of a chordate that are lost in the adult form. Neither reproduction nor development was observed on Heron Island, therefore the specific reproduction and development strategies of Trididemnum sp. was not established. 


Ascidians are a diverse group of benthic suspension feeders (Peterson, 2007). They pump a continuous water current through the mucous lined pharyngeal basket (mucous net) to trap suspended food particles. Water current is produced with the help of cilia located on the edges of the gill slits (site of respiration). Some ascidian species (including the Trididemnum sp. found on Heron) host symbiotic algae. The excess photosynthate produced by the algae may be used as a supplementary food source by the host ascidian. 





(2 objects, created 5/6/2011)

Album: This is a private album that is not visible to anonymous users Great Barrier Reef Invertebrates



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