Figure 1.
The basic morphology and internal anatomy of living cnidarians (anthozans, staurozoans, coronate scyphozoans, and cubozoans, excepting hydrozoans).
(A) A fully grown individual of Morbakka virulenta (Kishinouyea, 1910) (Charybdeida, Cubozoa) from Japan, lateral view. (B) Rectangle area in (A), showing the blade-like pedalia, velarium, frenula, interradial septa and gonad-lamellae. (C–D) A juvenile individual of living Tripedalia cystophora Conant, 1897 (Charybdeida, Cubozoa) from Japan. (C) Oral view, showing the triangular apertural lappets, four pairs in the perradii and eight in the adradii; note the incipient pedalia. (D) Lateral view. (E) Diagrammatic horizontal section of Tripedalia cystophora, showing the internal anatomy, especially the gonad-lamellae and the suspensia, modified from ([17], Figure 23). (F) An oral view of a staurozoans. (G) Diagrammatic comparison of the gonads and gonad-lamellae in horizontal sections between a cubozoan (lower part) and a staurozoan (upper part), modified from ([3], Figures 2–3). (H) Cross section of a coronate scyphozoan showing scalloped bell margin and internal gonads (simplified from Thiel,1966 [3]). (I) Cross section of an ideal hexanerous actiniarian through the pharynx (left) and below the pharynx (right), the numbers indicate the order of insertion of the new septa following the directive septa, modified from [2].
Figure 2.
Cubozoan embryos from the Lower Cambrian Kuanchuanpu Formation, Shaanxi, South China.
(A–B) SEM photographs of ELISN31-5, oral (A) and lateral view (B) of the SEM photos. (C–D) ELISN108-343; (C) SEM photograph of oral view. (D) Reconstruction of ELISN108-343 from Micro-CT analysis, in lateral view. (E–F) ELISN96-103. (E) SEM photograph, near-lateral view. (F) Lateral view of ELISN96-103 from Micro-CT analysis. (G) SEM photograph of ELISN66-15. (H) ELISN25-79. (I) ELISN35-42. All sections share the same scale bar (equals 300 µm) seen in (B).
Figure 3.
Micro-CT photographs of microscopic cubozoan ELISN31-5 from the Lower Cambrian Kuanchuanpu Formation, South China.
(A) Virtual vertical section of ELISN31-5 marked with a vertical dotted line by P′ in (P). (B–P) successive virtual horizontal sections of the same specimen from the aboral pole downward; their horizontal levels are marked by B′–P′ in (A) with white dotted lines.
Figure 4.
Interpretation of the virtual sections of cubozoan specimen ELISN31-5 from the Lower Cambrian Kuanchuanpu Formation, South China.
The horizontal position of these virtual sections is marked as those in Figure 3. All sections share the scale bar (equals to 300 µm) seen in B.
Figure 5.
Micro-CT photographs of the microscopic cubozoan (ELISN108-343) from the Lower Cambrian Kuanchuanpu Formation, Shaanxi, South China.
(A) Virtual vertical section marked with A′ in (S) by a vertical dotted line. (B–T) Successive virtual transverse sections through the orthogonal to oral-aboral axis starting from the aboral end, with their horizontal levels marked by B′–T′ with white dotted lines. Scale bar = 300 µm.
Figure 6.
Interpretation of the virtual sections of the cubozoan specimen ELISN108-343 from the Lower Cambrian Kuanchuanpu Formation, Ningqiang, Shaanxi, South China.
The position of these virtual sections is indicated as those in Figure 5. Scale bar = 300 µm.
Figure 7.
Micro-CT sections of two cubozoan specimens with five pairs of tentacles.
(A–F) ELISN 96-103. (A) Vertical section along the oral-aboral axis. (B–F) Horizontal sections. (G–L) ELISN66-15. (G) Vertical section along body axis. (H–L) Horizontal sections. Scale bar = 300 µm.
Figure 8.
Hypothetical life cycle of Cambrian cubozoans.
(i) A typical biphasic mode with planula and polyps. (ii) A sessile medusa stage after hatching of embryos. (iii) A shortened life history without free living planula and sessile polyp.