Clocks. They keep track of the passage of time and as a result, we humans have a very interesting relationship with them. Certain times bring us great joy, while others can fill us with something approaching dread.
Whenever clocks are involved, there are also alarms that inject themselves into the mix. Again, some alarms are the sources of intense joy (such as, the cookies are done and it’s time to take them out of the oven), while others can make the blood run cold (it’s Monday morning and it’s time to wake up for work). This is the inescapable characteristic of time.
Humans have invented many devices for keeping track of time. An hourglass is a beautiful item that can mark the passage of small amounts of time. There are also water clocks that do the same basic thing as an hourglass, except they use water instead of sand.
The ultimate “clock,” however, would have to be the sun. The rotation of Earth produces a reliable pattern of appearance and disappearance of the sun, and the orbit of the Earth around the sun produces changes in the “amount” of sun we receive. A sundial is an effective clock, but it’s not a particularly portable device and it doesn’t work at night.
Spring will not officially arrive for another couple weeks, but on Sunday, we acknowledged the coming change by moving the clocks ahead an hour. I won’t get into the history of daylight savings time here, but the basic idea (back in the days when people lit their homes and businesses with candles) was to take advantage of natural sunlight to save on expenses. Modern humans don’t have this problem and we could easily adjust our behavior without fooling ourselves about the time, but that hasn’t really caught on.
At this point in the year, the length of the daytime hours is increasing by three to four minutes per day. On March 20, we will hit that magical moment when there are 12 hours of light and 12 hours of dark during a day, and from then to June the days will only get longer. With this increase in daylight will come an increase in warmth, and in a matter of weeks we will shift from a time of frozen, snow-covered ground to a time of soft, yielding and aromatic soils covered with the green of life and the yellow of blooming dandelions.
Thus, we are about to witness the astounding work of the most important clocks in existence — the biochemical clocks that reside within the bodies of the plants and animals we share this part of the planet with. As just one example of the multitude of such clocks in existence, I present you today with the egg case of a praying mantis.
I found this item in the pile of firewood that was delivered to my house last autumn. Somehow, the egg case managed to survive the process of being loaded into, and unloaded from, a truck, and I was more than delighted when my eyes fell upon it. Inside the egg case (and others like it all across the landscape) lives the future of the praying mantis population. This is because the adult insects cannot endure the cold of winter, nor can they flee far enough to survive. As a result, the first few frosts of the year typically cleanse the landscape of insects, leaving only their eggs and pupae to survive the winter.
This egg case is filled with living creatures that are surviving in a sort of suspended animation while they wait for spring to present them with conditions that are more favorable. The clocks inside their bodies keep track of temperature and once the correct number of “degree days” have been reached, the hatching alarm goes off and the little insects emerge. The timing of this hatching is extremely important because the baby mantids are little carnivores and they must find other insects to feed upon. If they hatch too soon, they will starve to death.
The Northern Hemisphere is turning itself toward the sun once again, and in just a few weeks we will be able to go outside in short sleeves and bare feet. We will come home from work and enjoy more hours of daylight, and at some point we will even start cooking outside. It’s been a cold winter, but soon the cold will yield to the warm relief of spring. At this point, it’s just a matter of time.
Bill Danielson has been a professional writer and nature photographer for 21 years. He has worked for the National Park Service, the U.S. Forest Service and Massachusetts State Parks and currently teaches high school biology and physics. Visit speakingofnature.com for more information, or go to Speaking of Nature on Facebook.