Neopilina
| Neopilina | |
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| File:Neopilina001.jpg | |
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| Genus: | Neopilina
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Neopilina is a highly derived genus of modern monoplacophoran.[1] However, molecular methods show that they fall within the polyplacophoran clade,[2] and fossil and morphological data show that they are rather derived and bear very little resemblance to an 'ancestral mollusc'.[1]
Anatomy
Its anatomy[3] led researchers to believe that the cephalopods evolved from the monoplacophora.[3]
Its pair of preoral tentacles are considered homologous to those of gastropods; like prosobranch gastropod tentacles, their nerves connect to the cerebal ganglia of the brain.[3] The post-oral tentacles are equated with bivalves' labial flaps, cephalopods' arms, and scaphopods' captacula.[3]
Cuticular hardenings around the mouth of the organism are considered to be jaw-like and very not far removed from the beaks of cephalopods, or the jaws of many gastropods.[3]
The presence of a single shell prompts comparisons to the cephalopod Nautilus, but besides its bilateral symmetry and direction of coiling, there is not a clear equivalence; Nautlius' shell is notably different in the possession of septa (and thus a sphuncle).[3]: 64 It bears a similar degree of similarity to most other mollusc groups, leading to speculation that it may reflect a relatively unchanged ancestral mollusc.[3] The shell itself is aragonitic, consisting mainly of a prismatic layer,[4] lined with nacre.[3]
The organism bears five pairs of ctenidia, unusually for molluscs; the rear two are homologous to the two pairs in Nautilus. This is unlike the polyplacophora, who have a number of pairs of ctenidia, but this number varies and is not related to the number of their body 'segments'.[3]
The foot and pallial groove are very difficult indeed to discriminate from the polyplacophora,[3] supporting its placement in this group by molecular methods[2]
Ecology
Neopilina is a bottom feeder, probably a deposit feeder; whilst alive, its shell is covered by a layer of mucus that might be involved in feeding or locomotion.Attention: This template ({{ref jstor}}) is deprecated. To cite the publication identified by jstor:3565144, please use {{cite journal}} with |jstor=3565144 wrapped in <ref> instead.
References
- ^ a b Organisms, Genes and Evolution: Evolutionary Theory at the Crossroads ; Proceedings of the 7th International Senckenberg Conference By Dieter Stefan Peters, Michael Weingarten Contributor Dieter Stefan Peters Published by Franz Steiner Verlag, 2000 ISBN 351507659X, 9783515076593 243 pages
- ^ a b Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi: 10.1073/pnas.0602578103, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
|doi= 10.1073/pnas.0602578103instead. - ^ a b c d e f g h i j Lemche, H; Wingstrand, K.G. (1959). "The anatomy of Neopilina galatheae Lemche, 1957 (Mollusca, Tryblidiacea)" (Link to free full text + plates). Galathea Rep. 3: 9–73.
{{cite journal}}: line feed character in|journal=at position 9 (help) - ^ Stephen Weiner and Lia Addadi (2007). "Design strategies in mineralized biological materials" (PDF). - contains spectacular SEM of prismatic nature of aragonite shell.