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Hopefully you are all becoming accustomed to daylight-saving time. I heard comments in church Sunday on how glad they are that it will be lighter in the evenings. However, it will take me a few weeks to get use to the time change.
I thought when I retired, I would not be too concerned with the time of day; however, I am still on a time schedule.
Knowing the time has always been important for humans. Before we had clocks to give us the exact time, ancient people kept time by using the length of shadows, which grow longer and shorter depending on how high the sun is in the sky. These ancient people figured out that a day was approximately 24 hours, but the hours of night and day were not consistent.
Depending on the time of year, the daylight hours can be either shorter or longer than 12 hours. Eventually, the ancient Egyptians created a water clock, which the Greeks and Romans continued to use for many years.
The earliest water clocks were vessels designed with a hole in the bottom. After a vessel was filled with water, the water would drain out of the hole. The hour markings allowed the user to know the time. Most water clocks were designed to allow 12 hours for water to drain.
According to the book Animal Timekeepers by Navin Sullivan, people and animals follow the rhythms of day and night, which are caused by the rotating earth. Of course, Earth rotates approximately 365 times a year, while we are making this journey around the sun. As we travel around the sun, Earth tilts on its axis, which gives us our four seasons.
The two rhythms of man and animals are the seasons and day and night, however, there is a third rhythm that is important to some creatures: rhythm of the tides. Animals live according to this rhythm of the seasons.
The breeding, raising young, family breaking up and preparing for the winter season by either migrating, hibernating, or putting on extra fat and heavier coats are all done due to this rhythm. Light and darkness and the seasons govern the lives of animals by day and by year.
Some are sent on long journeys, while others go into deep sleep and still others put on heavy coats and extra body fat. They are acting according to their internal clocks set by the Earth, moon and sun.
The tides are caused by the pull of the moon, and as the earth rotates, the tides are carried to each shore in turn. Because of the monthly travels of the moon around the Earth, the moon is overhead at a particular place on Earth 50 minutes later each day. As a result the tides come 50 minutes later each day. There is a high tide and a low tide approximately every 12 1/2 hours.
Creatures living in and along the seas and oceans live according to this rhythm of the tides. If you were to take a walk on the beach during low tide, many barnacles would be found uncovered on the sandy beach. At low tide, sandpipers and fiddler crabs also appear on the sandy beach in search of food, however the barnacles aren't available to them since they have sealed themselves tight, making it almost impossible to be pried open.
Later at high tide when the barnacles are covered with water, the shells have opened for feeding time.
The fiddler crab changes color according to the time of day. In the morning, it has a silvery gray skin and as the day goes on, the fiddler crab's skin begins to darken. At noon, the skin is at its darkest and then begins to lighten until sunset when it is a silvery gray once again.
Some people living along the shore can tell the time of day by the color of the fiddler crab. Scientists believe the dark skin protects the crab from the sun's hot rays.
One might think that this change in colors occurs due to the sun, however in a study done on fiddler crabs that were taken from the beach and put in a completely darkened room, it was found that they continued to change colors according to the schedule followed on the beach.
Scientists believe the fiddler crabs have an inner clock, which keeps them in step with the 24-hour clock.
Then scientists placed fiddler crabs, from Cape Cod, Mass., into darkened containers, which were flown to Berkley, Calif., where day and night arrive over three hours later than on Cape Cod.
Half of the crabs were kept in darkened containers, and the other half were put out on the beach. The group in the containers stayed on the Cape Cod schedule, however those experiencing day and night on the beach altered their schedule, and after two days, these crabs were keeping time with the west coast. They had reset their internal clocks.
In another study, creatures such as bees that were taken to a new location reset their clocks according to daylight. The 13- and 17-year cicadas have an internal clock, which causes them to appear after spending years underground.
After many years, an internal clock brings salmon back to their birthplace to spawn. We humans also have this inner clock and even a one-hour change will be noticed. Those who travel for great distances are said to have jet lag until they reset their inner clocks.
One of the most remarkable timekeepers is the grunion, a small fish that lives off the coast of Southern California. Twice every month (once at full moon and once at new moon) there is an extra high tide, and during these tides, the waves go farther up onto the beach than at any other time.
The grunions ride the waves of these extra high tides and lay their eggs on the beach at the highest point reached by the water. Then, in 15 days, at the second extra high tide, as the water reaches the eggs, they hatch, and the young fish swim away.
A sea worm that lives in the waters off the West Indies also has an accurate inner clock. Each October, when the moon is just into the third quarter, the sea worms swarm on the surface of the Atlantic Ocean. The female worms give off a glowing light, which attracts the male.
On one of his journeys crossing the Atlantic Ocean, Christopher Columbus wrote in his journal (Oct. 11, 1492) that they saw mysterious lights on the ocean.
From the date recorded, we now know that the lights were from the swarming female sea worms.
Bill Bower is a retired Pennsylvania Game Commission Wildlife Officer. Read his blog and listen to his podcasts on the outdoors at www.onemaningreen.com.