The Effect Light Has on Tadpoles

Light affects the growth rate and activity cycle of tadpoles. The "types" of light also play a role. For example, tadpoles raised underneath a red light grow faster than those under bright white lights. In addition, a light source in a natural environment attracts mosquitoes and other insects. The tadpoles feed on the insect larvae, the food source important to their improved growth.

  1. Red Lights and Tadpoles

    • A study conducted in 2002 and 2003 by India's Gulbarga University Zoology Department showed that frogs and tadpoles perceive light with the help of a photosensitive pineal gland. Light detected by the photoreceptors in female frogs can affect ovaries. When red light interacts with a frog or tadpole's pineal hormones, growth, or in the case of a tadpole, metamorphosis, is accelerated. No adverse consequences were noted with the accelerated growth. Red light has a lower frequency and a longer wavelength than white light.

    Bright Lights

    • Tadpoles were more active under bright lights than with natural lighting, according to a study by Katherine V. McClure, Jordan W. Mora and Geoffrey R. Smith of Dennison University's Biology Department in Granville, Ohio. The study, published in 2009, used tadpoles from wood frogs exposed to low-, medium- and high-intensity light. In the study, lights were used in conjunction with shadow to simulate times of day and arrival of potential predators. The "shadow stimulus" activity was highest when the lights were brightest, meaning the tadpoles moved around more. The study varied based on the number of tadpoles in a tank, with more activity in the larger groups.

    Heightened Perception

    • The Ohio study suggests that tadpoles are better able to visually perceive predators under brighter light. Bullfrog tadpoles also showed more activity under brighter light. However, green frog tadpoles reduced their movement during daylight, when that particular species predators were more active.

    Light and Food

    • Light can influence the feeding cycle of tadpoles, according to a joint study by Micheline A. Kim of the Department of Forest Sciences, University of British Columbia, and John S. Richardson of the Wildlife Branch, British Columbia Environment. While several factors can work together, light is one component to the tadpoles' algal food supply, the researchers determined. Light spurs the growth of algae, which the tadpoles eat.

    Ultraviolet Light Problems

    • Researchers studying the global decline in amphibians believe ultraviolet sunlight, coupled with pollution, is cutting the number of tadpoles. A study conducted at the University of Ottawa in 2003 cited leopard frogs exposed to excessive ultraviolet rays for eight months. About four percent of the UV-subjected tadpoles reached maturity. Up to 11 percent of the tadpoles that were not overexposed survived to become adult frogs. In addition, the tadpoles overexposed to the UV rays matured slower. Researchers believe the excessive exposure negatively impacts the tadpoles' hormones, thereby affecting their growth.

    Light Tied to Heat

    • Light can also be tied to temperature, as the sun warms the water the tadpoles are growing in. Typically in a pond, tadpoles rest in the shallows. They move more in the light, and feed more often. As areas of a pond warm under sunlight, tadpoles move into them. During cloudy days, tadpoles are less active, the cloud cover cutting both light and heat.