For eons, people have believed that the full moon and lunar cycles, in general, have all sorts of crazy effects on humans. Often referred to as the “Transylvania Effect” full moons particularly have been implicated in a colorful assortment of curious circumstances and lunar lunacy. Because the moon’s cycles are known to influence natural phenomena like the tides, many cultures have developed the belief that lunar phases also influence human emotions, behaviors, and health.
This Halloween will bring a full moon, which is a rare occurrence on Halloween to begin with. The last time it happened in our time zone was 1944. Given the current situation so far this year, there is at least one little comforting reality: the moon is not to blame. There are plenty of anecdotal stories floating around about police departments and hospitals gearing up and adding extra staff for full moons, and some of those stories may even be true this is more likely to be cases of “illusory correlation,” which is a brainy term for an error in thinking. Believing something is true without having all the facts and data can easily lead some people to reach flawed conclusions. Often, the belief alone is enough to influence behavior but where the moon is concerned, there is no proven direct correlation.
However, lunar cycles affect wildlife in fascinating ways. Most people are familiar with circadian rhythm which follows the daily cycle of sunlight. But circalunar rhythm is an actual biorhythm that corresponds with the lunar cycle (approximately 29.5 days). The reproductive cycles of many organisms, especially marine organisms, are linked to changing levels of moonlight and the tidal cycle, both of which are governed by the phases of the moon.
Coral spawning happens all over the world but the largest is a spectacular phenomenon that happens each year between October and December on the Great Barrier Reef. On or right after a full moon, male and female corals release reproductive cells, called gametes, into the water. The plume, which is often described as an underwater blizzard, is so large that it can be seen from space. Closer to home, a similar spawning takes place on the reefs of the Florida Keys and attracts scores of enthusiastic divers and snorkelers all looking to witness one of nature’s most dazzling underwater shows.
Anglers know that fish of all types are affected by the lunar cycles. The strongest tides, known as Spring Tides, happen during a new moon and full moon. These occur when the earth, sun, and moon are aligned resulting in bigger tides both high and low. Fish are most active during Spring Tides both in terms of feeding and reproduction. Around seven days after a full moon, the sun and moon are at right angles to each other which reduces the gravitational pull, resulting in a Neap Tide, a time where tides are not quite as dramatic. The moon appears half-full during this phase, the first and third quarter moon. Most serious fishermen know the bite is best between a new and full moon and usually plan their fishing accordingly.
Moonlight, in addition to the great coral spawning, also has a good deal of influence on other types of wildlife. Most people know that nocturnal animals use the light of the moon for hunting and foraging but even more fascinating is how that lack of moonlight can change animal behavior. For example, lions of the Serengeti are notorious night stalkers and will take advantage of the darkness of a new moon to hunt. But a recent citizen science project revealed that the common wildebeest, which makes up a third of the lion’s diet, are onto them. During new moons they tend to park themselves in a safe place, delaying most nocturnal activity to the safety of a bright full moon. We can also see the effect of moonlight and its absence right here on our own beaches. Sea turtle hatchlings move in the brightest direction which is most often the open view of the night sky over and reflected by the ocean. While this ability does not depend solely on lunar light and can happen during any phase of the moon, the presence of artificial light coming from the wrong direction during a new moon can and often does disorient them.
These are only a few examples of how our nearest celestial neighbor influences life on earth. But humans, for the most part, have lunar immunity which can only be a good thing this year. So, we wish all of you a safe and happy Halloween filled only treats and the knowledge that should you bump into any tricks, don’t blame it on the moon!