{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,15]],"date-time":"2026-10-15T06:01:34Z","timestamp":1792044094152,"version":"4.4.0"},"reference-count":60,"publisher":"Wiley","issue":"7","license":[{"start":{"date-parts":[[2023,5,18]],"date-time":"2023-05-18T00:00:00Z","timestamp":1684368000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001659","name":"Deutsche Forschungsgemeinschaft","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100001659","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000008","name":"David and Lucile Packard Foundation","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100000008","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Journal of Morphology"],"published-print":{"date-parts":[[2023,7]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>Appendicularia comprises 70 marine, invertebrate, chordate species. Appendicularians play important ecological and evolutionary roles, yet their morphological disparity remains understudied. Most appendicularians are small, develop rapidly, and with a stereotyped cell lineage, leading to the hypothesis that Appendicularia derived progenetically from an ascidian\u2010like ancestor. Here, we describe the detailed anatomy of the central nervous system of<jats:italic>Bathochordaeus stygius<\/jats:italic>, a giant appendicularian from the mesopelagic. We show that the brain consists of a forebrain with on average smaller and more uniform cells and a hindbrain, in which cell shapes and sizes vary to a greater extent. Cell count for the brain was 102. We demonstrate the presence of three paired brain nerves. Brain nerve 1 traces into the epidermis of the upper lip region and consists of several fibers with some supportive bulb cells in its course. Brain nerve 2 innervates oral sensory organs and brain nerve 3 innervates the ciliary ring of the gill slits and lateral epidermis. Brain nerve 3 is asymmetric, with the right nerve consisting of two neurites originating posterior to the left one that contains three neurites. Similarities and differences to the anatomy of the brain of the model species<jats:italic>Oikopleura dioica<\/jats:italic>are discussed. We interpret the small number of cells in the brain of<jats:italic>B. stygius<\/jats:italic>as an evolutionary trace of miniaturization and conclude that giant appendicularians evolved from a small, progenetic ancestor that secondarily increased in size within Appendicularia.<\/jats:p>","DOI":"10.1002\/jmor.21598","type":"journal-article","created":{"date-parts":[[2023,5,18]],"date-time":"2023-05-18T19:20:33Z","timestamp":1684437633000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Evolutionary traces of miniaturization in a giant\u2014Comparative anatomy of brain and brain nerves in<i>Bathochordaeus stygius<\/i>(Tunicata, Appendicularia)"],"prefix":"10.1002","volume":"284","author":[{"given":"Berit","family":"Zemann","sequence":"first","affiliation":[{"name":"Museum f\u00fcr Naturkunde Berlin Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mai\u2010Lee Van","family":"Le","sequence":"additional","affiliation":[{"name":"Humboldt\u2010Universit\u00e4t zu Berlin, Vergleichende Elektronenmikroskopie Berlin Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5474-9880","authenticated-orcid":false,"given":"Rob E.","family":"Sherlock","sequence":"additional","affiliation":[{"name":"Monterey Bay Aquarium Research Institute Moss Landing California USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Daniel","family":"Baum","sequence":"additional","affiliation":[{"name":"Zuse\u2010Institut Berlin Berlin Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7249-0147","authenticated-orcid":false,"given":"Kakani","family":"Katija","sequence":"additional","affiliation":[{"name":"Monterey Bay Aquarium Research Institute Moss Landing California USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5461-9069","authenticated-orcid":false,"given":"Thomas","family":"Stach","sequence":"additional","affiliation":[{"name":"Humboldt\u2010Universit\u00e4t zu Berlin, Vergleichende Elektronenmikroskopie Berlin Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2023,5,18]]},"reference":[{"key":"e_1_2_8_2_1","first-page":"309","volume-title":"Response of marine ecosystems to global change: Ecological impact of appendicularians","author":"Alldredge A. 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