Fig 1.
Paraplanocera oligoglena (Schmarda, 1859) specimen collected at Longdong Bay, Taiwan on August 5th, 2022.
(A) Dorsal view with anterior end on the right; (B) Ventral view with anterior end on the left. b, brain; ph, pharynx; s, sexual organ; t, tentacle; u, uterus.
Fig 2.
Images of Paraplanocera oligoglena.
(A) Before staining, (B) after staining with fluorescein, and (C) after staining with methylene blue, which shows the digestive system comprising blind sacs, simple circulative loops, and extensive branching.
Fig 3.
Consecutive ordering of tract branches from the pharynx toward the distal margin.
The pharynx is indicated as 0, and then the numbers from 1 to 5 correspond to every segment of the digestive tract in each order.
Fig 4.
Post-staining image of Paraplanocera oligoglena after image processing.
The red color indicates regions containing stained food. It shows a whole-body image with ROIs clearly illustrating the extreme complexity of the gastrovascular cavity.
Fig 5.
Sequential video captures of bidirectional flow.
From (A) to (B) shows the inward gastrovascular flow and from (C) to (D) shows the outward flow in the same track. Red arrows indicate the direction of flow.
Fig 6.
Post-staining video tracking of dyed food passing through consecutive branches n, n+1, n+2, and n+3.
The timing of the events was as follows: Inward peristalsis (0 to 40 sec); change in the direction of gastrovascular flow (40 to 55 sec.); outward peristalsis (55 to 85 sec.). The wave trough of the curve indicates the duration of each contraction, while the period between two peaks and wave troughs represents a single peristalsis cycle.
Fig 7.
Contraction period in consecutive order of the tract branches, n, n+1, and n+2 during the inward and outward flows.
The seconds of contraction in order ’n’ are marked as circle dots, in ’n+1’are marked as solid squares, and in ’n+2’ are marked as triangles. The ANOVA shows that designated inward flows have no significant differences in consecutive branches(n = 30, p = 0.50). The outward flows also show no significant differences between consecutive branches (n = 30, p = 0.67).
Fig 8.
Variations in tract volume on the 1st, 2nd, and 3rd days.
Fig 9.
Radial muscle within the digestive tract of Paraplanocera oligoglena.
(A) Longitudinal section highlighting the radial muscles with arrows. (B) Cross-section of a radial structure.