Five phenomena caused by the moon
Moon is the only natural satellite of Earth. Its age is not much different from that of Earth. It is tidally locked to the Earth. In other words, it takes the same time to revolve around the Earth as it takes to rotate around its own axis. Located at 384,402 km from the Earth, it’s effects are pronounced on our planet. Moon impacts many systems and life cycles on our planet, and paves the way for many phenomena. This includes reproduction, navigation, and migration in many species. Apart from that, events like Eclipse and Tides are the easiest to perceive.
Let’s look at five phenomena caused by the moon in detail.
1. Circalunar rhythms
Circadian rhythm is a term you must have heard of. It is the cycle of day and night caused by Earth’s revolution around the sun. But, there is also a circalunar rhythm, driven by the moon’s cycles.
Circalunar rhythm is a biological rhythm that runs along with the lunar cycle which lasts approximately 29.5 days. Several organisms, especially marine life, display changes in life cycle according to this rhythm. Although they are difficult to detect, they have a different impact on different organisms. Let’s check a few examples.
Certain species under Pocilliopora reproduces all year and follow a lunar rhythm. During winters the reproduction is associated with the full moon and in summers it responds to the new moon. This has nothing to do with low tides and high tides. But it is the combined effect of water pressure, tidal amplitude, and air exposure. The cycle is irregular but follows the lunar month.
The lunar rhythm’s impact on some organisms is a response to the changing intensity of light. Gonad species mature following a circalunar rhythm. They respond to the changing intensity of light, from sunlight to night skies without the moon. Some species of Odontosyllis also have a similar reproduction response.
Some littoral species respond to the changing tides too. For instance, tide pool fish exits rock pools to search for more food. Further, sea anemones expand as the tide rises.
2. Moon Compass.
Lunar impacts result in what is sometimes called moon compass. In this, several organisms use moon’s light as navigation source. Let’s check out some examples of the same.
Sand hoppers are a species that find difficulty in staying in the marine front that suits their ideal habitat. A simple mistake could lead them to death from drying up on the beach. So, they have developed a natural compass that responds to both sun and the moon. Their sun compass is located in their brains and their moon compass on their antennae. Using this, they stay buried throughout the day and safely go out to forage for prey in the night.
An example of organisms using lunar rhythm is the dung beetle. They use moonlight just like a compass. In fact, the precision of their navigation depends on the changing phase of the moon. They thrive in South African Grasslands where these beetles survive on dung. A species called Escarabaeus satyrus hunts for dung at night. They find the dung and roll them into a ball. Later, they have to roll it to a place where they store it safely. But this poses a challenge: navigation during the night.
Hoppers use the moon’s rhythm to navigate.
To prevent going round and round in darkness, the beetles make use of polarized moonlight. As light reflects off gas molecules, they polarize and send light waves of the same frequency around. Beetles can detect this polarized light and use it to guide them to their destination.
Another great example of the lunar compass is the Barau’s petrel. It is an endangered seabird species, that used the island of Reunion to breed. They set off on pre and post- breeding migrations by measuring the length of days. It waits for 12.5 hours before starting out. Although their arrival at the place is different each year, they arrive during the same phenomena: full moon. This suggests that they synchronize their migrations depending on moon’s cycles as well as the length of days.
3. Mass Spawning of Corals.
The mass spawning of corals in the Great Barrier Reef is a beautiful event that takes place on our planet. In the process of spawning, millions and billions of coral polyps discharge their sperm and egg into the ocean. There are different factors like salinity, proper temperature, and food dictating the event. But it always happens after a full moon between October and December.
It is a defining visual event and can even be spotted from the space. This is because is it well coordinated and the entire region spawns at the same time.
The corals use three main triggers before they begin their spawning event. They are Full moon, sunset(perceived using photoreceptors), and a chemical which lets them smell one another.
Many coral reef species also display what is referred to as lunar or semi-lunar periodicity for procreation. This means, their spawning reaches the highest level either once in each lunar cycle or twice in each lunar cycle. Following this cycle helps them to time their behavior in synchrony with other members of their species. This, in turn, helps them to breed.
4. Lunar Eclipse
Lunar Eclipse is an event that takes place when the Moon moves into the Earth’s shadow. It happens when Earth, Moon, and the Sun are in the same alignment. Note that Earth has to be located between the other two for Lunar Eclipse to occur Also, it has to happen on a full moon. The duration of the eclipse varies based on the moon’s position relative to its orbit.
Sometimes, the moon turns reddish, leading to a dramatic eclipse. This is called a blood moon. It happens when a totally eclipsed moon is completely deprived of sunlight by the Earth. When it happens, the little light reflected off the moon’s surface is refracted by Earth’s atmosphere. Hence, this light has the same hues of a sunrise or a sunset, as explained by Rayleight’s scattering.
Lunar Eclipse also affects life forms on the Earth. For instance, a nocturnal species in Argentina, the Azara’s owl monkeys stopped their hunt during the lunar eclipse. This is because of the sudden that falls during the lunar eclipse.
5. High and Low Tides
Tides refer to the rise and fall in sea levels due to the compound effect of the gravitational force exerted by the Sun and the Moon, and the rotation of the Earth.
Tidal force from the moon falls the strongest on the side of Earth facing the Moon. Meanwhile, it is the feeblest on the side away from the Moon. As a result of this difference in gravitation, our ocean water bulges. It bulges out in opposite directions on different faces of the Earth. The ocean waters on the side facing the moon bulge towards the moon. On the opposite side of the earth, the ocean water bulges away from the moon. In other words, the Moon’s gravitation exerts its force on the entire planet and not just the ocean water.
When ocean water bulges, it is called high tide. On the side facing the moon, it is called high high tide. On the Earth’s opposite face, it is called low high tide. Out in the ocean, water bulges towards the moon while it spreads out and covers more land along the shores.
Meanwhile, the regions between the high tides are regions of low water levels due to the bulges happening. This is called low tide. When water flows from a high tide region o a low tide region, it is referred to as an ebb tide.
Tides are usually semidiurnal or taking place twice per day. The tidal range is the difference in height level between the high tide and low tide. The tidal range changes every month depending on the changing effect of the Sun’s gravitational force on the Earth.
Impact of Tides On Life
Tides impact marine life as discussed earlier. Fish move in their habitat depending on the tide. When tides fall, small animals move to deep waters to prevent getting trapped within rock pools. This is because, during this time, the temperature and salinity can vary to a great degree during this time. However, when they move, predators wait in the expected route of movement and pounce upon them. Animals that survive return to their initial habitats when water rolls back.
Hence, reproductive cycles and other activities of fish depend on tide timing. This helps fishermen to time their hunt perfectly for better yield.
Note that edible marine animals including seaweed, crabs, mussels, and snails live in the tidal zone. Without a regular flow of tides, these animals and their life systems would collapse.
Apart from that, tides help in navigation. For instance, ships can approach the shores easily when the tide is high. Every 24 hours, two high tides and two low tides occur. Using an appropriate apparatus to harness the falling and rising water levels, a healthy amount of energy can be produced.
As you can see, the moon’s impact on the Earth’s life forms run deep. Although many phenomenons are too subtle to notice, they have many-layered impact on our ecosystems.