acorn worm

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Related to acorn worms: Hemichordata, Lancelets

acorn worm

a hemichordate, one of the three groups of invertebrate chordates collectively referred to as PROTOCHORDATES.
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Reports are also rare on the abundances of these groups and acorn worms for the Eastern Tropical Pacific region.
The 1984-1987 survey: Examples of the acorn worms and brachiopods collected are included in Fig.
One gene cluster preserved for more than half a billion years is though to be linked to the development of the pharynx - the passageway linking the nasal cavity to the mouth and throat - in both acorn worms and vertebrates.
Moreover, we examined histological sections of the infected tissues of the acorn worms and the gut contents of their parasites to better understand the parasite-host relationships.
Acorn worms Ptychodera flava were collected monthly from September to December 2009, as well as in June 2010 and June 2011, with a shovel in the sandy beach at Chito, Penghu Islands, Taiwan (23[degrees]38'54.
Acorn worms are themselves part of the hemichordates, a group of marine animals closely related to today's sea stars and sea urchins.
It's astonishing how similar Spartobranchus tenuis fossils are to modern day acorn worms, except that they also formed fibrous tubes," he noted.
It's astonishing how similar Spartobranchus tenuis fossils are to modern-day acorn worms, except that they also formed fibrous tubes.
Researchers say these tubes were lost in the lineage that resulted in modern-day acorn worms, but were retained through graptolites and pterobranchs.
Shallow water acorn worms live in burrows and are rarely seen, whereas deep sea species browse on the sea floor leaving spiral poo traces that resemble crop circles.
abundance and trail characteristics of acorn worms at Australian continental margins.