Structure and signaling at hydroid polyp-stolon junctions, revisited.

The gastrovascular system of colonial hydroids is central to homeostasis, yet its functional biology remains poorly understood. A probe (2',7'-dichlorodihydrofluorescein diacetate) for reactive oxygen species (ROS) identified fluorescent objects at polyp-stolon junctions that emit high levels of ROS. A nuclear probe (Hoechst 33342) does not co-localize with these objects, while a mitochondrial probe (rhodamine 123) does.

Physiological correlates of symbiont migration during bleaching of two octocoral species.

Perturbed colonies of Phenganax parrini and Sarcothelia sp. exhibit migration of symbionts of Symbiodinium spp. into the stolons.

Within-colony migration of symbionts during bleaching of octocorals.

Octocorals compose a major part of cnidarian diversity. As with other symbiont-containing cnidarians, octocorals are susceptible to a stress response and subsequent "bleaching," which typically involves the loss of photosynthetic dinoflagellate symbionts. Studies of bleaching often focus on hexacorals, including sea anemones and scleractinians.

Circulation of fluids in the gastrovascular system of a stoloniferan octocoral.

Cilia-based transport systems characterize sponges and placozoans. Cilia are employed in cnidarian gastrovascular systems as well, but typically function in concert with muscular contractions. Previous reports suggest that anthozoans may be an exception to this pattern, utilizing only cilia in their gastrovascular systems.