Dipleurula
pelagic
(free-floating). The ciliated bands are not drawn.Dipleurula is a hypothetical
ciliated
echinoderm larva (cilia devoted to movement, feeding and perception).
Etymology
Derives from Ancient Greek di, meaning 'two' and the small form of pleura (pleurula), meaning 'little side', i.e. 'little, two-sided [larva]'.[2]
History
Although the term dipleurula stems from Semon (1888),[3][4]
it was first systematically introduced, described and drawn by Bather (1900) in his monography on the echinoderms.bilaterian animals.
The original doliolaria schema shows a
benthic
, crawling, larva. However Bather could not have known yet that larval echinoderms are typically pelagic (free-floating plankton).
Structure
The hypothetical dipleurula larva bears resemblance to stages of all extant echinoderms, such as the
crinoids (sea-lilies and feather stars) can be attributed to the same basic pattern.[3][5][6] Note, that the extant echinoderms represent just a small window on the extraordinary diversity of early echinoderms as known from their rich fossil record.[7] Although there is current research on fossilized larval skeletons,[8]
the doliolaria remains a hypothesis.
The doliolaria shows a three-partite body, each of which develop paired coelomic spaces which originate from the
deuterostomes.[3]
The anterior coeloms are known as axocoel, the medial ones as hydrocoel and the posterior ones as somatocoels. In extant echinoderm larva, the coeloms on the right side of the larva are typically much smaller than the ones on the left side, or even rudimentary. The right hydrocoel may fuse with the right axocoel.[5][6]
References
- ^ a b Bather, F.A. (1900). A treatise on zoology, Part III. The Echinodermata. London, UK: Adam & Charles Black. p. 344.
- ^ "Lexikon der Biologie". Spektrum.
- ^ a b c Hyman, Libbie Henrietta (1955). The invertebrates. Vol. IV. Echinodermata. New York: McGraw-Hill. p. 763.
- ^ Gupta, Tapashi (24 Feb 2021). "Dipleurula Concept & Echinoderm Theory of Origin of Chordates". Retrieved 7 May 2023.
- ^ ISBN 9783827415752.
- ^ a b Kardong, Kenneth V. (2006). Vertebrates: Comparative Anatomy, Function, Evolution (4 ed.). pp. 72–75.
- ^ Raymond C. Moore; Curt Teichert; P. A. Selden, eds. (1967–2011). Treatise on invertebrate paleontology (Part S-U) Echinodermata 1-3. Kansas: Geological Society of America, University of Kansas.
- ISBN 978-3-910807-00-6.
External links
- Information on forn
- "Dipleurula". de:Lexikon der Biologie (in German). Spektrum Akademischer Verlag. Heidelberg. 1999. Retrieved 2019-12-30.