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Abstract Ctenophores are descendants of an early branching basal metazoan lineage, which may have evolved neurons and muscles independently from other animals.Mnemiopsisis one of the important reference ctenophore species. However, little is known about its neuromuscular organization. Here, we mapped and tracked the development of the neural and muscular elements in the early hatching cydippid larvae, as well as adultMnemiopsis leidyi. The overall development of the neuromuscular system inMnemiopsiswas very similar toPleurobrachia bachei, although inMnemiopsisthe entire process occurred significantly faster. The subepithelial neural cells were observed immediately after hatching. This population consisted of a dozen of separated individual neurons with short neurites. In about 2 days, when their neurites grew significantly longer and connected to their neighbors, they began to form a canonical polygonal subepithelial network. Mesogleal neural elements prominent in all studied adult ctenophores were not detectable inMnemiopsislarvae but were clearly labeled in closely related Lobata speciesBolinopsis infundibulum. Hatched larvae also had putative mechanoreceptors with long stereocilia and approximately two dozen muscle cells. In adultMnemiopsis,the feeding lobes and auricles contained two distinct populations of neurons and neural ensembles that were not observed in other ctenophore lineages and likely represented elaborate neuronal innovations characteristic for the clade Lobata and their lifestyles.
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This content will become publicly available on October 28, 2025
Ex situ spawning, larval development, and settlement in massive reef‐building corals ( Porites ) in Palau
Abstract Reproduction, embryological development, and settlement of corals are critical for survival of coral reefs through larval propagation. Yet, for many species of corals, a basic understanding of the early life‐history stages is lacking. In this study, we report our observations forex situreproduction in the massive reef‐building coralPoritescf.P. lobataacross 2 years. Spawning occurred in April and May, on the first day after the full moon with at least 2 h of darkness between sunset and moonrise, on a rising tide. Only a small proportion of corals observed had mature gametes or spawned (14–35%). Eggs were 185–311 μm in diameter, spherical, homogenous, and provisioned with 95–155 algal cells (family Symbiodiniaceae). Males spawned before females, andex situfertilization rates were high for the first 2 h after egg release. Larvae were elliptical, ~300 μm long, and symbiotic. Just 2 days after fertilization, many larvae swam near the bottom of culture dishes and were competent to settle. Settlers began calcification 2 days after metamorphosis, and tentacles were developed 10 days after attachment. Our observations contrast with previous studies by suggesting an abbreviated pelagic larval period inPoritescf.P. lobata, which could lead to the isolation of some populations. The high thermal tolerance and broad geographic range ofPoritescf.P. lobatasuggest that this species could locally adapt to a wide range of environmental conditions, especially if larvae are locally retained. The results of this study can inform future work on reproduction, larval biology, dispersal, and recruitment inPoritescf.P. lobata, which could have an ecological advantage over less resilient coral species under future climate change.
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- PAR ID:
- 10555508
- Publisher / Repository:
- Invertebrate Biology
- Date Published:
- Journal Name:
- Invertebrate Biology
- ISSN:
- 1077-8306
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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