One of the wonders of life on planet Earth is the influence of sunlight. As winter fades away and summer approaches, we see all kinds of changes in life. As scientific research continues into the wonders of the animal and plant kingdoms, we see more carefully designed biological systems. Here are some examples of how sunlight affects life cycles:
COCCOLITHOPHORES: These are tiny phytoplankton plants that live in the ocean. As the season changes and the Sun warms the waters, those organisms increase their rate of reproduction. They would smother themselves with overcrowding except for the fact that they give off dimethyl sulfide. That chemical rises into the atmosphere and oxidizes into solid sulfate particles. For raindrops to form, there must be moisture, cool temperatures, and condensation nuclei. The solid sulfate particles provide the condensation nuclei, and the rising air cools the moisture from the sea resulting in clouds. The clouds block the sunlight, thus cooling the sea and slowing down the reproduction rate of the coccolithophores and avoiding a massive die-off. This phytoplankton literally manipulates the weather to ensure its own survival.
SALMON. These fish know when to return to the waters of their birth to spawn. Built into their bodies is a pineal gland that stimulates the pituitary gland, triggering an urge to spawn. Navigation tools designed into the salmon allow them to find the place of their origin where they spawn and die.
BEAN APHIDS AND OTHER ANIMALS. Bean aphids give birth when the length of the day reaches 14 hours and 55 minutes, assuring that the offspring will have warmth. Similar triggers by sunlight affects life cycles, allowing muskox to shed their insular undercoat, mallard ducks to shed their winter down, and snowshoe hares to change their color from white to brown before all the snow melts.
FROM FRUITFLIES TO HUMANS. Fruitflies shed their pupal husk an hour before dawn even when kept in the dark. Even when kept in total darkness, hummingbirds slip into torpor at dusk, allowing them to conserve energy. A poppy folds its petals at dusk, even in a dark box. Both the hummingbird and the poppy will resume operations at dawn, even in the darkness. Scientists are still researching what triggers these changes even without sunlight. Medical researchers are also studying how humans respond to a lack of sunlight, causing seasonal affective disorders (SAD).
Studying the incredible ways in which sunlight affects life cycles on Earth is a great way to grow in appreciation for the creation process. We marvel at the careful design built into all living things. David looked at himself and his world and remarked, “I will praise you, for I am fearfully and wonderfully made: marvelous are your works…” (Psalms 139:14).
John N. Clayton © 2020
These examples were found in National Wildlife magazine Volume 32 # 1.
