Halimeda tuna is a seaweed belonging to the Halimedaceae family. It owes its name to the Taino term 'tuna', which means cactus, in reference to the way in which this species grows. It is characterized by the formation of stems up to 20 cm high, formed by fragments in the form of kidney-shaped and flat discs up to 2.5 cm in diameter, linked together. The fragments are thicker at their ends and generally present calcareous incrustations. The different fragments are always aligned with each other following the same plane. The color of Halimeda tuna is a yellowish-brown green with a slight whitish tone due to the calicification present in this species.
We will find this species predominantly on rocky bottoms and with depths ranging from the surface to a maximum of 75 meters deep. It is a species that adapts well to moderately shady places with little water movement. Geographically, its distribution is very wide, its only requirement being warm water. A curious fact about this algae, is that they are able to synchronize the time of reproduction, when this happens, the algae completely change their color, becoming whitish. This fact is due to the transformation of the cells of the edges of each of the segments, in reproductive cells, which will release the spores to the water.
Halimeda tuna is part of the diet of a not very striking opistobranchian, but which is perfectly camouflaged in this algae, it is Bosellia mimica. Therefore, by observing this algae very carefully and patiently, we will be able to observe this opistobranchium.
As a curiosity of this species, several scientific works have been reported in which diverse compounds have been isolated from Halimeda tuna specimens. These compounds have shown interesting antioxidant, antifungal, antiviral and antimicrobial properties. For example, the compound halitunal presents an activity against the murine coronavirus A59, while diverse extracts of this species have been shown to be effective against diverse batteries (Staphylococcus aureus, Salmonella typhimurium, Salmonella paratyphi, Klebsiella oxytoca and Escherichia Coli), as well as against various fungi (Aspergillus niger, Aspergillus flavus, Alternaria alternata, Candida albicans, Epidermophyton floccosum, Trichophyton mentagrophytes, Trichophyton rubrum and Penicillium sp). It should also be noted that certain molecules present in algae of the genus Dicyota are capable of causing physiological alterations in the algae Halimeda tuna.Photos: