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Pleurobranchaea meckelii.jpg
A live individual of Pleurobranchaea meckelii; the gill (or ctenidium) is visible in this view of the right-hand side of the animal
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Orthogastropoda (older classification)
Superorder: Heterobranchia (older classification)
Order: Opisthobranchia (older classification)
Suborder: Notaspidea
P. Fischer, 1883

See text

Notaspidea, also known as the sidegill slugs, was a suborder which included both sea slugs and sea snails or false limpets, marine opisthobranch gastropod molluscs in the subclass Orthogastropoda.

Adult notaspideans are carnivorous or feed on dead matter. Their anatomy is characterized by a single, external ctenidium (respiratory apparatus) on the right side, rolled rhinophores, and a flattened shell.

The families Tylodinidae and Umbraculidae show large limpet-like external shells and a small mantle, while the species in the family Pleurobranchidae have a prominent mantle and an internal shell that becomes reduced or is lost in adults.[1] Many species produce mantle secretions as a chemical defense against predators [2]


However, in the newer taxonomy of Bouchet & Rocroi (2005), the families Umbraculidae and Tylodinidae belong to the superfamily Umbraculoidea Dall, 1889, part of the clade Umbraculida. Grande et al. (2004) found Umbraculoidea to be a sister clade to the Cephalaspidea (Acteonoidea excluded).[3]


  1. ^ R. Willan (1987). "Phylogenetic systematics of the Notaspidea (Opisthobranchia) with a reappraisal of families and genera". AM; Malacol. Bull. 5: 215–241. 
  2. ^ Aldo Spinella, Ernesto Mollo, Enrico Trivellone and Guido Cimino (December 1997). "Testudinariol A and B, two unusual triterpenoids from the skin and the mucus of the marine mollusc Pleurobrancus testudinarius". Tetrahedron 53 (49): 16891–16896. doi:10.1016/S0040-4020(97)10124-7. 
  3. ^ Grande C., J. Templado, J.L. Cervera, R. Zardoya (2004). "Phylogenetic relationships among Opisthobranchia (Mollusca, Gastropoda) based on mitochondrial cox1, tmV, and rmL genes". Molecular Phylogenetics and Evolution 33 (2): 378–388. doi:10.1016/j.ympev.2004.06.008. PMID 15336672.