Sponge Description

Class Hexactinellida Schmidt, 1870 Order Lyssacinosida Zittel, 1877

Family Euplectellidae ? Gray, 1867 or Rossellidae ? Schulze, 1885

Skeleton type 1 (Pl. 11A)

Habit: Small globular, ovate or probably ficiform species. Cross sections indicate diameters of about 1.2-2.2 cm. Neither a big spongocoel nor a distinct pore system was found. Only a few aligned spicules indicate inarticulate gastral-like structures. The kind of substrate attachment remains unknown, but is assumed to be lophophytous or the sponge was partially burried in the sediment. While parenchymal spicules are scarce, the dermal layer is characterized by a 1 mm broad zone of bigger spicules that are mostly aligned with the outline of the sponge.

Skeleton: Lyssacinosid type with exclusively isolated spicules. Parenchymalia are small monaxons and regular hexactins, the rays of which are 30-50 µm thin and 500-600 µm long. The dermal layer displays hexactins and some reduced forms (pentactins, stauractins?), also probably centrotylots. Their rays vary from 100-130 µm.

Skeleton type 2 (Pl. 11B)

Habit: Bulbous or short columnar species with a distinct aquiferous system and a differentiation into centered bundles of monaxons and a surrounding parenchymal skeleton. The skeletons show diameters of 3-5.5 cm. This size and furthermore the different detected growth forms are so unique, that they are attributed to a separate morphotype although similar spicule configurations are expected at the base of sponges showing the skeleton type 4.

Skeleton: Lyssacinosid type with exclusively isolated spicules. The center shows 150-200 µm thick diactin oxeas in bundles or in slightly plumose configuration. Outer mesohyle areas are characterized by mainly hexactin and pentactin principalia, whereas dermalia are small hexactins and thin oxeas.

Skeleton type 3 (Pl. 11C)

Habit: Small cup-shaped sponges, probably encompassing several similarly formed species.

Individuals with diameters of 1.5-2.1 cm were detected. They possess walls that vary from 3-5 mm in thickness. While ostias or canals are not preserved, the skeletons are characterized by a noticeable high amount of different spicules and distinctly accentuated dermal and gastral layers.

Skeleton: Lyssacinosid type with exclusively isolated spicules. The mesohyle shows big hexactins with rays about 120 µm thick and 2-3 mm long. Smaller hexactins, pentactins, and monaxons with thinner rays (20-50 µm, 0.6 mm long) are dispersed in between. Identical spicules, but bigger in size, are concentrated in the dermal and gastral layers.

Skeleton type 4 (Pl. 10F, 11D)

Habit: Tubular species of 8-10 cm in size. Without any stalk they were attached with their bases to irregular firmgrounds or spicular mats presumably by thick monaxons (lophophytous). Their walls are quite consistent, usually 5-7 mm thick, forming tubes of 2.5-6.5 cm in diameter. A distinct aquiferous system is developed showing 500-750 µm wide ostia and ramifying canals (schizorhyse system) that are best observed in pyritized samples. Dermal and gastral layers are not clearly defined, but sporadically accentuated by a slightly higher ratio of spicules.

Skeleton: Lyssacinosid type with almost exclusively isolated spicules. Principalia are mainly long-shafted hexactins, secondarily reduced forms like pentactins and probably centrotylot ones.

They all display rays with 50-100 µm in diameter and different lengths up to 1-2 mm.

Parenchymalia intermedia and/or dermalia frequently occur. They are smaller, possess clearly thinner rays (25-50 µm in diameter, 750 µm in length), and vary from hexactins to diactins. Very rarely two or three small hexactins are fused to short tracks. Dermal and gastral layers are sometimes additionally stabilized by different thicker and short-shafted spicules. Hypodermalia or prostalia pleuralia are absent.

Skeleton type 5 (Pl. 11E)

Habit: Species of unknown shape. Cross cuts of 2-3 cm big fragments are all characterized by cavities of 2-3 mm in size. The spicules are rather small and very thin-rayed in comparison to those of the other species.

Skeleton: Lyssacinosid type with exclusively isolated spicules. Mainly hexactins, pentactins, and diactins occur. Mainly the pentactins function as canalaria. Rays are 30-50 µm in diameter and 0.5-1 mm in length.

Class Hexactinellida Schmidt, 1870 Order Hexactinosida Schrammen, 1903

Family Euretidae ? Zittel, 1877

Skeleton type 6 (Pl. 13A)

Habit: Only fragments were found, thus its shape is more or less unknown. The skeletal remains correspond to globular, hemispheric or bulbous species.

Skeleton: Euretid type with a meshwork of fused hexactins. The rays of the spicules are 60-80 µm thick. They form a nearly cubic meshwork with 400-500 µm wide interstices that expand radial-concentrically. Triangular or polygonal meshes occur infrequently.

Family Tretodictyidae ? Schulze, 1886

Skeleton type 7 (Pl. 13C, D)

Habit: Cup-shaped to tubular species, attaining diameters of 3.5-4.5 cm and heights of 6 cm or more. Distinct wall structures, 0.5-1cm in thickness, display a schizorhyse aquiferous system and 0.5-0.7 mm wide ostia.

Skeleton: Euretid type with mainly fused spicules. Dictyonal skeleton of hexactins that form short tracks or bigger clusters of a basically cubic meshwork, that get often disturbed by intercalated triangular or polygonal meshes thus eluding the canals of the aquiferous system.

Internodes measure 160-240 µm. The rays of the spicules are 25-30 µm thick.

Skeleton type 8 (Pl. 13B)

Habit: Several small tubes, 2-5 mm in diameter, either protruding from a common base or growing side by side. Features of an aquiferous system were not detected.

Skeleton: Euretid type with predominantly fused spicules. The dictyonal skeleton consists of fused hexactins that form a radial-concentric meshwork, according to the tubular growth.

Internodes measure 200-300 µm. The rays of the spicules are thin, about 25-30 µm in diameter.

Fig. 29a. Skeleton types and assumed growth forms (center) of lyssacinosid sponges (Schnöll Formation, Rot-Grau-Schnöll Quarry, Adnet). Obtained and interpolated from thin sections.