Scientists say that frog populations across three continents are suffering from a new parasitic disease.
Thomas Richards, co-leader of the study, from Exeter University, said that global tadpole populations are experiencing a steep decline due to a recently discovered disease, as a prominent factor.
Tadpoles are the aquatic juvenile stages of a frog or a toad, exhibiting gills (related to their respiratory system), a long, laterally flattened tail. The tadpoles’ respiration is facilitated by their external or internal gills. They don’t have limbs in early stages. When a tadpole morphs into an adult, its legs and lungs develop, whereas the tail gradually disappears. There’s also another intermediary stage, a juvenile frog, developing in between tadpole and the adult frog statuses.
As they turn into adults, the tadpoles’ mouths change from a small, enclosed mouth at the top of the head into a large one, having the same width as their heads.
Concerning their eating habits, they feed on algae and plants, they’re herbivorous. Some species are omnivorous and may even feed on smaller tadpoles.
Their size varies according to the different species they pertain to.
Tadpoles are usually aquatic creatures, however some are terrestrial or semi-terrestrial. They swim using their tail by lateral undulation, similar to the movements of most fish. So, ondulatory motion is a means to propel an animal forward by wave-like movement. Snakes as well rely on ondulatory locomotion.
Richards’ team of British scientists discovered that frogs had been contracting a highly infectious, parasitic disease caused by unicellular organisms called “protists” found in the tadpoles’ livers. Samples were taken and examined from six countries.
The findings were published in the Proceedings of the National Academy of Sciences Journal on Monday. Along with University of Exeter, the National History Museum also contributed to developing the study.
Protists are single-celled microbial agents, which store their DNA in a nucleus.
The disease spread rapidly in tropical and temperate areas, and it is believed to be related to oyster parasites.
In 2008, 32 percent of amphibians were cataloged as threatened or extinct, whereas 43 percent were put in the category “in decline”.
The consequence of the deterioration of amphibian populations (and other animals as well) is that Earth is traversing through a mass extinction era, the sixth of its kind. This mass extinction event could become prominent in 250 years and could be compared to the decline and death of dinosaurs, because of its rapidly spreading aspect.
Photo Credits livescience.com