Tunicata

Definition and stakes

William Abbott Herdman,  1911 Encyclopædia Britannica (1911)

“ It is now known to be a degenerate branch of the Chordata, and to be more nearly related to the Vertebrata than to any group of the Invertebrata. The Tunicata are found in all seas, from the littoral zone down to abyssal depths. They occur either fixed or free, solitary, aggregated or in colonies. The fixed forms are the “simple” and “compound” Ascidians. The colonies are produced by budding and the members are conveniently known as Ascidiozooids. Some Tunicata undergo alternation of generations, and most of them show a retrograde metamorphosis in their life-history. ”
Source: Wikisource

Various,  Encyclopaedia Britannica, 11th Edition…

“ In the Tunicata the remarkable tadpole larva, the structure and development of which was first elucidated by the great Russian naturalist, A. Kowalevsky, possesses a similar interest to that of the nauplius larva of Cirripeds, and of the tornaria larva of the Enteropneusta, in that it pointed the way to the recognition of the affinities of the Tunicata, affinities which were entirely unsuspected till they were revealed by a study of the larvae. ”
Source: Gutenberg

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