What’s red in the daytime, and glows an eerie blue at night? Although it may sound like some illuminated prop from the forthcoming film Solo: A Star Wars Story, the answer to this oceanic riddle has less to do with science fiction, and everything to do with one of nature’s little marvels: bioluminescent phytoplankton.
Nighttime beachgoers in San Diego have recently been treated to this unusual spectacle, as the recent arrival of a red tide has resulted in natural luminous phenomena that occur as plantlike microorganisms present in ocean waves tumble downward with the incoming tide, producing a visible glow.
According to NOAA, there are two main varieties of phytoplankton: diatoms and dinoflagellates, the latter being the type that are presently seen along San Diego’s shoreline.
“Dinoflagellates use a whip-like tail, or flagella, to move through the water and their bodies are covered with complex shells. Diatoms also have shells, but they are made of a different substance and their structure is rigid and made of interlocking parts. Diatoms do not rely on flagella to move through the water and instead rely on ocean currents to travel through the water.”
The appearance of these phytoplankton has to do with the occurrence of red tides, where oceanic algal blooms–sometimes harmful ones–grow in such abundance that they become overrun in certain coastal environments. This can have dangerous effects on not just the indigenous marine life in affected areas, but also humans. Illnesses that are known to occur in conjunction with these potentially toxic algal blooms have been known to cause debilitating illness or even death.
There are a variety of unique luminous displays that occur in nature, particularly with bioluminescent marine life. However, it may be the case that not all oceanic luminous displays necessarily have biological origins. On April 29, 1982, a most unusual visual display occurred in the China Sea, which resulted in a six-page report on the incident. The details of this nighttime encounter, presented here in abbreviated form, consisted of parallel bands of phosphorescence that appeared to be rushing toward the ship at an estimated speed of 40 miles per hour.
Upon contact with the luminous bands, they appeared to separate into rotating “wheels”, which became oriented roughly in quadrant formation around the ship. It is particularly noteworthy, however, that these luminous manifestations were seen above the surface of the water. Each of the spinning wheels appeared to be 50-100 cm above the water, with beams of light being cast from these formations which the sailing vessel’s crew described as having “stretched to the horizon” as they rotated. Additional luminous phenomena were reported during this incident, which appeared to be composed of “worm-like segments” of light.
Other key features of the incident involved the presence of atmospheric electrical activity (i.e. lightning) throughout the incident; at various intervals, it was further noted that shining an Aldis lamp at portions of the luminous manifestations had no effect, while flashing it caused the intermittent disappearance of the phenomenon altogether (this is similar to reports of what are believed to be natural plasmas that appear at locations like Hessdalen, Norway, which have been known to interact similarly with flashing lights aimed in their direction).
The symmetrical, and at times nearly kaleidoscopic displays presented in the case above, documented in the Marine Observer in 1983, are certainly perplexing. While dissimilar in variety to the unusual illuminations that are presently occurring off the San Diego coast, each represents a unique manifestation of natural luminous phenomenon that occasionally apear in or around our oceans.