Definition: number of currently described and taxonomically accepted marine species in this clade (Appeltans et al. 2012. The Magnitude of Global Marine Species Diversity. Current Biology 22, 2189–2202. http://dx.doi.org/10.1016/j.cub.2012.09.036)
Definition: A morphological quality inhering in a bearer by virtue of the bearer's ratios of distances between its features (points, edges, surfaces and also holes etc).
Comment: Shapes are invariant on size transformations. Shapes can be subdivided into 2D and 3D shapes, We can also make a distinction between shapes of complete self-connected objects, and shapes of parts of objects.