Pterobranchia
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Pterobranchia, members of which are often called pterobranchs, is a class of small worm-shaped animals. They belong to the Hemichordata, and live in secreted tubes on the ocean floor. Pterobranchia fe
Cephalodiscus nigrescens
Acorn worm
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The acorn worms or Enteropneusta are a hemichordate class of invertebrates. The closest non-hemichordate relatives of the Enteropneusta are the echinoderms. There are 111 known species of acorn worm i
Pterobranchia
…report on Cephalodiscus was published in 1887, it became clear that Cephalodiscus, the second genus now included in the order, had affinities with the Enteropneusta. Electron microscope studies have suggested that pterobranchs belong to the same clade as the extinct graptolites, and phylogenetic analysis suggests…
Acorn worm on the ocean floor
Acorn worm life cycle by M. Singh