Fireflies have been observed glowing in the night belong to the order Coleoptera. Lampyridae is the family of insects particularly beetles commonly known as fireflies or light bugs because their bioluminescent property to attract mates as well as prey. Fireflies are known to produce cold light as it lacks any infrared or ultraviolet frequency. The light produced by them may be pale yellow, green or red and is produced from the lower abdominal region with the wavelength range of 510-670 nanometers. They are known to colonize temperate and tropical region and around 2,000 species are known at present. They are known to live in marshes or wet areas as the larvae get plenty of food in these environments. Larvae are also known to emit light and are known as glow worms particularly in Eurasia.
Fireflies are brown coloured, soft bodied insects with a leathery elytra rather than hard as found in other beetles. The females resemble males in their external appearance but larviform females have been noticed in some species. These larviform females can be distinguished from the larvae by the feature that they have large compound eyes. Majority of species of fireflies are nocturnal but few are nocturnal also. The diurnal species are non-luminescent while those dwelling in the shadowy areas are able to emit light. The female lays eggs few days after mating. Eggs are laid either on land or underground. Eggs hatch into tiny larvae which feed till the end of summer. Larvae are commonly known as glow worms so should not be confused with the members belonging to the family Phengodidae. The term glow worm is actually used both for the larvae as well as adults of the genus Lampyris noctiluca. In the European glow worm the female are non-flying and emit bright light continuously while the males emit weak and intermittent light.
Fireflies undergo hibernation during winters and some remain in diapause for several years. They hibernate either underground or in the bark of the trees. They emerge in spring. Larvae undergo pupation, which last for 1-2.5 weeks and then the adults emerge out. Larvae are predators of snails, slugs and other small insects. They have well developed mandibles for this purpose. The diet of adults is variable. Some are predatory while others feed on nectar and pollen. Some species are distasteful or even toxic for some vertebrate predators. This is because fireflies have chemicals known as lucibufagins similar to cardiotonic bufadienolides found in some poisonous toads. Production of light by the fireflies is the outcome of a chemical reaction known as bioluminescence. This reaction takes place in specialized light emitting organs preent in the lower abdomen of fireflies. Enzyme luciferase acts on luciferin in the presence of magnesium ion, ATP and oxygen to produce light. Genes coding for this phenonmemnon have been inserted in other organisms as well.
Firefly luciferase finds use in forensics as well in the medical sciences for the detection of magnesium and ATP. All fireflies glow as larvae. The emitted light acts as a signal for attracting mates as well as for warding off the predators. Female Photuris fireflies are known for mimicking the mating flashes of other lightning bugs for the sole purpose of predation. Target males are attracted towards these females and are eaten. Many fireflies do not produce light at all. These are diurnal and use pheromones as signals for attracting mates. Males also use visual cues for detecting females.
Fireflies or glow worms are also captured by children as means of entertainment. Nature has gifted every organism many unique tactics which help it to enjoy the benefits of environment.
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