schelploos

Schelploos is a Dutch-language term used to describe organisms that lack a protective external shell. The word combines schel, meaning shell, with loos, meaning without. In everyday usage, schelploos mainly refers to shell-less mollusks, most notably slugs, which are terrestrial gastropods that either never develop a shell or have shed it during evolution. In scientific writing, the term is descriptive rather than taxonomic; researchers typically specify the exact group or species, or use established names such as naaktslak for slugs. The concept can also be applied to other shell-less organisms, including some nudibranchs, though these are usually identified by their taxonomic names rather than by the general label schelploos.

Morphology: The defining feature is the absence of a calcareous shell. Shell-less forms may display adaptations such as a reduced mantle, enhanced mucus production, or other structural changes that compensate for the lack of a shell.

Ecology: Shell-less organisms often rely on moist environments to prevent desiccation and may use camouflage, chemical defenses, or other strategies to avoid predation. Their life histories and habitats vary widely among the different groups that can be described as schelploos.

Notes: Schelploos is an informal descriptor rather than a formal taxonomic category. For precise communication, it is preferable to refer to the specific taxon (for example, slug, nudibranch) or to describe the absence of a shell within the relevant group.

See also: Slug, Nudibranch, Mollusca, Shell (biology).