Introduction: The Portuguese man o’ war, an aquatic invertebrate, is responsible for a large proportion of cnidarian stings worldwide. Cnidaria is a phylum that contains the genus Physalia. These injuries result in severe pain and skin irritation, which are often difficult to control. Traditionally, cnidarian stings have been treated by emergency physicians with warm water, vinegar and, in severe cases, opioids. However, no concrete guidelines have been established for pain management in man o’ war stings.

Case Report: Regional anesthesia (RA) is an increasingly used method of pain control in the emergency department. In the case of a 41-year-old female experiencing severe pain from a Portuguese man o’ war sting, RA with an erector spinae plane block (ESPB) provided her with rapid and long-lasting pain relief.

Conclusion: The standard of care has yet to be defined when managing pain from Physalia physalis stings. Although this is the first documented use of ESPB for treatment of cnidarian stings, RA should be considered by any emergency physician when treating injuries caused by a Portuguese man o’ war.

Convergent evolution of complex phenotypes like eyes offers us an important opportunity to investigate the redeployment and divergence of genetic components used to build those complex phenotypes. While eyes evolved convergently among animals with sophisticated neural machinery to process visual information, they surprisingly also evolved in animals with simpler nervous systems and highly capable of eye regeneration, such as jellyfish. Because eyes are formed by discrete parts, each with known genetic pathways in model systems, they are an ideal system for understanding the evolutionary trajectories underlying convergent evolution of complex phenotypes. Did eyes in jellyfish evolve convergently? And if so, to what extent do they employ similar genes and where did their parts come from? I explored these questions by integrating evidence at several levels of biological organization. First, I inferred the largest cnidarian species phylogeny to date, which allowed me to test how many times jellyfish eyes evolved. I found that eyes originated convergently at least eight times among the swimming jellyfish stage. Next, I focused on three species with convergent eyes to investigate the extent to which vision genes differentially expressed in their eye-bearing tissues were similar. I found that most genes involved in eye development and phototransduction pathways in convergent eyes are upregulated in a lineage-specific way. Comparing these findings with previous knowledge from a few other jellyfish species suggested that eyes belonging to the same evolutionary origin might employ a very predictable set of vision genes. Finally, I asked what the ancestral organismal function of photoreceptor cells was before they became part of jellyfish eyes. Based on experiments in four species of cnidarians, I found support for the hypothesis that ancestral photoreceptor cells modulated the discharge of stinging cells in the cnidarian ancestor. Such an ancient photosensory function could have long sustained a role for photoreceptor cells and perhaps facilitated multiple eye origins in the group. My dissertation work advanced a new emergent system for comparative research on eye evolution, development and function, underscored the potential for convergent eyes to have mostly unique evolutionary trajectories, and uncovered ancient sensory tasks that predated eye origins.

Flagellate dermatitis (FD) exhibits a striking clinical appearance similar to whiplash marks. General dermatologists are likely to encounter this clinical appearance as a more localized presentation of phytophotodermatosis. Jellyfish stings may also cause localized linear or FD. Chemotherapeutic agents such as bleomycin, doxorubicin, docetaxel, and trastuzumab are well-recognized causes of a widespread FD and it may more rarely be seen in connective tissue disease such as dermatomyositis or Still disease. In our case, this was a presentation of shiitake mushroom dermatitis.

Photosymbioses between cnidarian hosts and Symbiodiniaceae algae enable the success of coral reef ecosystems. Algae remain photosynthetically active in symbiosis capturing light energy to fix CO2, evolve O2, and produce photosynthates which are transferred to hosts as substrate for growth and metabolism. Host cells phagocytose free-living algae and sequester them in arrested phagosomes, termed “symbiosomes,” enabling control over symbionts’ metabolisms promoting the production of photosynthates while regulating symbiont population growth. The underlying cellular mechanisms are mostly unknown and only a V-type H+-ATPase (VHA)-dependent carbon-concentrating mechanism (CCM) is documented in corals. My thesis sought to identify whether the CCM is widespread in cnidarian photosymbioses, establish the CCM’s importance under various environmental conditions, and identify nitrogen transport mechanisms. Chapter 2 describes the cloning of a candidate coral NH3/NH4+ (total ammonia, Tamm) channel (ayRhp1) from Acropora yongei. Heterologous expression in Xenopus oocytes and flux assays determined ayRhp1 is a dual NH3/CO2 gas channel. Immunofluoresence Airyscan confocal microscopy (IACM) revealed ayRhp1 is present in the symbiosome membrane where, together with VHA, it concentrates Tamm in the symbiont’s microenvironment. Furthermore, ayRhp1 is preferentially present in the symbiosome membrane during the day; presumably to provide algae with Tamm to ensure photosynthate production during photosynthesis. Chapter 3 tested whether Cassiopea jellyfish, which host their symbiotic algae in motile cells called amebocytes, employ a CCM like that from coral host cells. Western blotting and AICM revealed that Cassiopea amebocytes express both VHA and carbonic anhydrase (CA) and that both proteins localized to the symbiosome membrane. Respirometry using VHA and CA inhibitors revealed significant reductions in O2 evolution rate, a proxy for photosynthetic activity, suggesting that host VHA and CA are functionally coupled in the CCM. Chapter 4 explored the prevalence of the CCM in the coral Stylophora pistillata after acclimation to various environmental light conditions. While VHA protein abundance correlated with increased irradiance, AICM found limited symbiosomal VHA and respirometry experiments did not detect functional evidence for CCMs. Instead, VHA was prominently observed in calcifying cells, where it may contribute to pH regulation for biomineralization. Together, my thesis advances our mechanistic understanding of nutrient exchange in cnidarian photosymbioses.