Showing posts with label insects. Show all posts
Showing posts with label insects. Show all posts

Saturday, February 9, 2013

Fireflies glow


How does a firefly produce it's glow?


The simplest answer would be bioluminescence. But that alone doesn't explain the mechanism and the rationale of exposing your whereabouts to potential predators at night.


Fireflies are familiar, but few realize that these insects are actually beetles, nocturnal beetles. Most fireflies are winged, which distinguishes them from other luminescent insects of the same family, commonly known as glow worms.
Glow worm. Image:barryjnorthern.blogspot.com
There are about 2,000 firefly species, thriving in a variety of warm environments, as well as in more temperate regions. Fireflies love moisture and often live in humid regions of Asia and the Americas. In drier areas, they are found around wet or damp areas that retain moisture.
Image: animals.howstuffworks.com
Fireflies have dedicated light organs that are located under their abdomens. The insects take in oxygen and, inside special cells, combine it with a substance called luciferin to produce light with almost no heat. Wow.

Firefly light is usually intermittent, and flashes in patterns that are unique to each species. Each blinking pattern is an optical signal that helps fireflies find potential mates, though we aren't sure exactly how the insects regulate this process to turn their lights on and off.
Image: animals.howstuffworks.com
Firefly light may also serve as a defense mechanism that flashes a clear warning of the insect's unappetizing taste. The fact that even larvae are luminescent lends support to this theory. Females deposit their eggs in the ground, which is where larvae develop to adulthood. Underground larvae feed on worms and slugs by injecting them with a numbing fluid. Adults eschew such prey and typically feed on nectar or pollen, though some adults do not eat at all.



Why do fireflies glow?



One reason that fireflies glow is to attract a mate. Males and females of the same species will flash signals back and forth as a way of communicating. Each firefly species has its own particular pattern. For example, the fireflies of one species will fly around in the night sky and dive steeply just as the flash begins and turn upward to make a distinctive J-shaped pattern of light. Female fireflies hang out on a tree branch or in the grass while the males fly around showing off their best flashes. When a female recognizes the flash from a male of the same species, she will answer with her best flash.





Another reason that fireflies glow is to avoid predators. Fireflies are filled with a nasty tasting chemical called lucibufagens, and after a predator gets a mouthful, it quickly learns to associate the firefly's glow with this bad taste! So not only does the flashing help attract a mate, but it also warns predators to stay away.


Other creatures with bioluminescence.

Other glowing animals would be those eerie-looking deep sea dwellers; angler fish, and certain species of shrimp and plankton.
Angler fish. Image: animals.nationalgeographic.com
Image: lukaj.net


info: 

Monday, December 24, 2012

Dung Beetles Love Human Poops


Dung Beetles Love Human Poops

Why would anyone want to check out whose manure taste the best, I don't know. But it's exhilarating to know that we've won the interspecies dung contest (or rather, the first runner up).

The judges for the contest would happily chomp on any manure, and yes, they're a group of nine thousand dung beetles.
Image: scientificamerican.com
Two entomologists, Sean Whipple and W. Wyatt Hoback set out to an organic cattle ranch where there were plenty of dung beetles crawling around. They took dungs from several animals native to North America (bison, cougar, moose), and also from animals from other parts of the world (tiger, lion, zebra), and presented them to the panel of dung experts.

Different beetle species favored different types of dung. But dungs from omnivore were clear winners, and chimpanzee and human feces were right there at the top. Carnivore dungs were more attractive than most herbivore dungs. And even more amazing, the two least attractive dungs were those coming from two native species, the bison and the moose (clearly I was expecting the beetles to stick to their staple diet).
Image: blogs.discovermagazine.com
The researchers then tested the nutritional level of the dung, and found out that human dung had the highest nitrogen content, which meant the human dung were of the highest quality.

This, however, is not the reason why our dung were so sought after. As for the difference in diet, the authors said the exotic dungs were collected from a local zoo, where the carnivores were fed the same diet, so were the herbivores. So, the fact that the beetles favored different types of poops suggested there was more to poop flavor than the diet.

I believe it's the smell.



info: 
Whipple, S., & Hoback, W. (2012). A Comparison of Dung Beetle (Coleoptera: Scarabaeidae) Attraction to Native and Exotic Mammal Dung Environmental Entomology, 41 (2), 238-244 DOI: 10.1603/EN11285