My last trip left me with a huge question: how do sea animals responde to lunar cycles?
It all happened last week end…
We went to San Blas and found a turtle conservation center. There are many in Mexico and normally they take over the turtle eggs once the mother leaves them buried in the sand.
Turtle eggs and baby turtles are very delicate and vulnerable to predators. One of the worse ones is the seagull.
This is the container where the hatched babies are kept for few weeks.
My friend’s finger serves as a reference to understand their size. They’re absolutely tiny 🙂
The procedure is simple: few weeks after the eggs hatch the babies are ready to go into the sea. Because of the presence of predators, the center guardians protect them carefully to make sure that the babies are able to walk safely from the beach right into the water. This is to ensure that a significant number of them make it safely.
However, it happens that one of more baby turtles are unfortunate and/or somehow face bigger challenge. Below is a deformed turtle which never developed disproportioned limbs and one of them completely inexistent.
The moon revolves around the Earth in an elliptical orbit. But astronomically, these two bodies revolve around their own center which is also revolving around the sun. Because of this synchronised rotation and revolution of the moon, only the near side of the moon is seen facing the earth.
As common as this birth defect can be in animals, I found the explanation of the center guardian quite interesting. She explains that baby turtles can be born with defects and deformations due to lunar eclipses (in fact that had been one only few days earlier our visit).
So how does that work? How to marine creatures react to lunar eclipses?
The indirect effect of lunar cycle on the marine environment is the tide as in response to the gravitational pull of the moon to the earth.
This attraction is is strongest on the side of the earth facing the moon causing a bulge of water.
This is a schematic drawing that shows the high tides on the lunar portion of earth’s side.
There had been studies on the effects of lunar cycle on the behavioural patterns of marine animals. Some of these researches are focused on certain marine creatures that seem to show occurrence of lunar rhythms and their respective mechanisms to adapt with their environmental changes.
Some scientists also argue that certain animal behaviour is a response to lunar stimuli (like moonlight) while others reason that most marine animals have adapted to the long-term cycles and continue to persist because of “biological clock”.
The sun and moon cause rhythmic changes in our environment as in light, temperature in a predictable manner. These variations inevitably affect us humans, plants and animals and we can see how behaviour is adapted to these changes by improving and/or changing body parts that are no longer beneficial.
However… I still fail to find evidence that supports the notion that a lunar eclipse is harmful during turtle pregnancyso I think maybe it’s a myth or some sort of superstition. Humans are big on superstitions, remember my past stories on the most common Italian myths and believes?
This particular superstition about how lunar eclipse affects unborn baby animals is ingrained in India.
So what happened to the unfortunate baby turtle? Well, it was safely released the following dawn into the sea. Her limbs were disproportioned as you can see in the photos but they still allowed her to move around the box with her peers so hopefully she’ll manage to swim.