No image available. | Word: Actine Description: A centered ray containing an axis or axial canal. See also CLAD. Synonyms: Ray Category: Calcareous Spicules and Calcareous Spicule Skeleton |
| Word: Anchor Description: Anchor-like spicule, protruding free from the basal part of the sponge; derived from diactine, triactine, or tetractine spicules, with terminal rays or spines, curved in the proximal direction along the main ray Category: Calcareous Spicules and Calcareous Spicule Skeleton |
| Word: Apical actine (ray) Description: The fourth actine of a tetractine that is joined to the basal triradiate system Category: Calcareous Spicules and Calcareous Spicule Skeleton |
| Word: Articulate skeleton Description: Choanoskeleton composed of several rows of similar spicules Category: Calcareous Spicules and Calcareous Spicule Skeleton |
No image available. | Word: Atrial spicule/skeleton Description: Spicules surrounding the atrium. Terms "gastral spicule/skeleton" are to be rejected. Synonyms: Gastral Category: Calcareous Spicules and Calcareous Spicule Skeleton |
| Word: Basal triradiate system Description: The three rays of a tetractine that correspond to those of a triactine Category: Calcareous Spicules and Calcareous Spicule Skeleton |
No image available. | Word: Calcareous spicule Description: A spicule composed largely of calcite having a radiate form, the number of rays being either two (diactine), three (triactine), or four (tetractine). Category: Calcareous Spicules and Calcareous Spicule Skeleton |
No image available. | Word: Calcareous tripod Description: Regular triactine whose center is not in the same plane as the extremities of the recurved rays. Category: Calcareous Spicules and Calcareous Spicule Skeleton |
No image available. | Word: Center Description: Point of union of the three rays of a triactine or of a basal triradiate system. Category: Calcareous Spicules and Calcareous Spicule Skeleton |
| Word: Chiactine Description: Tetractine with the unpaired ray of the basal system and the apical ray in the same alignment Category: Calcareous Spicules and Calcareous Spicule Skeleton |
| Word: Choanoskeleton Description: Skeleton of the part of the sponge that contains choanocytes Category: Calcareous Spicules and Calcareous Spicule Skeleton |
No image available. | Word: Cortical spicule/skeleton Description: Spicule or skeleton of the external layer or cortex of the sponge ("dermal" spicule/skeleton, incorrect) Category: Calcareous Spicules and Calcareous Spicule Skeleton |
| Word: Diactine Description: A spicule composed of two actines Category: Calcareous Spicules and Calcareous Spicule Skeleton |
| Word: Diapason (tuning-fork spicule) Description: Sagittal triactine with parallel paired rays Category: Calcareous Spicules and Calcareous Spicule Skeleton |
No image available. | Word: Facial plane Description: The plane passing through tips of the three rays of a triactine or of a basal triradiate system of a tetractine. Category: Calcareous Spicules and Calcareous Spicule Skeleton |
| Word: Free actine Description: A ray that projects through the external or the atrial surface. Category: Calcareous Spicules and Calcareous Spicule Skeleton |
| Word: Inarticulate skeleton Description: Choanoskeleton composed only of the unpaired rays of the subatrial spicules and of one of the rays of the cortical or subcortical spicules. Without specific spicules of the choanoskeleton Category: Calcareous Spicules and Calcareous Spicule Skeleton |
No image available. | Word: Microanchor Description: A small tetractine anchor (described only from the atrial skeleton). Category: Calcareous Spicules and Calcareous Spicule Skeleton |
 | Word: Microdiactin Description: A small diactine spicule Category: Calcareous Spicules and Calcareous Spicule Skeleton |
 | Word: Needle-like biradiate Description: A diactine with a hole at one end Category: Calcareous Spicules and Calcareous Spicule Skeleton |
No image available. | Word: Optic axis Description: The crystallographic trigonal axis of the calcite spicule. Category: Calcareous Spicules and Calcareous Spicule Skeleton |
No image available. | Word: Paired actine(s) Description: One or both equivalent rays of a sagittal spicule. "Oscular" or "oral" rays to be rejected. Synonyms: Oral/oscular ray Category: Calcareous Spicules and Calcareous Spicule Skeleton |
| Word: Parasagittal spicule Description: Bilaterally symmetrical triactine or tetractine with unequal actines, having equal angles (120 degrees) between the basal rays when projected into a plane perpendicular to the optic axis "Secondary sagittal spicule" to be rejected. Synonyms: Secondary sagittal spicule Category: Calcareous Spicules and Calcareous Spicule Skeleton |
| Word: Pseudosagittal spicule Description: A subcortical triactine essentially sagittal, but having unequally long and differently curved rays on each side of the unpaired angle Category: Calcareous Spicules and Calcareous Spicule Skeleton |
 | Word: Regular spicule Description: Triactine or tetractine spicule with basal rays of equal length, and with equal angles (120 degrees) between them, when projected into a plane perpendicular to the optic axis Category: Calcareous Spicules and Calcareous Spicule Skeleton |
| Word: Sagittal spicule Description: Triactine or tetractine with two equal angles (paired angles) and one dissimilar angle (unpaired angle) at the center, when projected into a plane perpendicular to the optic axis "Primary sagittal spicule" to be rejected. Synonyms: Primary sagittal spicule Category: Calcareous Spicules and Calcareous Spicule Skeleton |
 | Word: Scale Description: Disc-shaped microsclere forming ectosomal ("dermal") armor (genus Lepidosphera) Category: Calcareous Spicules and Calcareous Spicule Skeleton |
| Word: Subatrial spicule Description: Sagittal spicule with paired rays adjacent to the atrial skeleton. "Subgastral spicule" to be rejected. Category: Calcareous Spicules and Calcareous Spicule Skeleton |
| Word: Subcortical spicule Description: A pseudosagittal triactine, with unpaired actine and a shorter paired actine adjacent to the cortex, or a tetractine with basal triradiate system adjacent to the cortex. Category: Calcareous Spicules and Calcareous Spicule Skeleton |
No image available. | Word: Subdermal spicule Description: Term to be rejected. See SUBCORTICAL SPICULE. Category: Calcareous Spicules and Calcareous Spicule Skeleton |
No image available. | Word: Subgastral spicule Description: Term to be rejected. See SUBATRIAL SPICULE. Category: Calcareous Spicules and Calcareous Spicule Skeleton |
No image available. | Word: Tangential spicule Description: Spicule arranged parallel to the surface. Category: Calcareous Spicules and Calcareous Spicule Skeleton |
| Word: Tetractine Description: A spicule with four rays (in figure, sagittal tetractine at the top and regular tetractine at the bottom). Category: Calcareous Spicules and Calcareous Spicule Skeleton |
| Word: Triactine Description: A spicule with three rays. Category: Calcareous Spicules and Calcareous Spicule Skeleton |
No image available. | Word: Trichox Description: Thin, hair-like straight monaxon spicules present in general around the osculum or protruding from the cortex. Category: Calcareous Spicules and Calcareous Spicule Skeleton |
No image available. | Word: Unpaired actine Description: In sagittal spicules, the ray of a triactine or of a triradiate basal system of a tetractine lying in the plane of bilateral symmetry. "Basal ray" to be rejected. Synonyms: Basal actine (ray) Category: Calcareous Spicules and Calcareous Spicule Skeleton |