Alaskan wood frog, wood frog, or wood frog has the scientific name Lithobates sylvaticus or Rana sylvatica. Is a frog that tolerates extreme conditions (freezing) which are mostly found in northern Alaska and Canada.
The Alaskan wood frog comes from the Ranidae family, so it is related to Rana esculenta (water frog), R. sakuraii, Lithobates capito, and others. Uniquely, the Alaskan wood frog can survive in freezing conditions for 7 months at a temperature of -20°C.
In addition, wood frogs have a different metabolic system from other frogs. Their body metabolism produces metabolites in the form of glucose.
In addition, there are other components that contribute to extreme climate tolerance, namely antifreeze glycolipids, and urea.
Alaskan Wood Frog Characteristics
Morphology and General Characteristics The Alaskan wood frog is of medium size, ranging from 3.5 cm to 7.6 cm with the female being larger than the male.
This species has several variations of color change, namely brown, brown, and rust. But it can also be found in shades of green and gray.
However, we can distinguish this frog from the presence of black spots that extend from the tympanum to the base of the forelimbs. Because of this pattern, this frog is also called a frog with a robber mask.
In addition, this frog also has a white line above its lips and yellowish-brown lateral folds. In addition, the lower body is white and yellow-orange toward the back. However, male frogs have a lighter color on the front of the legs. The average body weight of the Alaskan wood frog is 7.8 grams.
Alaskan wood frog eggs take different times to hatch, depending on the temperature of the water. Generally, eggs that frogs lay in cold waters take longer to hatch than eggs in warm waters.
Meanwhile, the Alaskan wood frog is estimated to live up to 4-5 years in nature. They also include diurnal animals, which are active during the day. Habitat and Distribution Alaskan wood frogs inhabit a variety of habitats, such as tundra, shrubs, wet meadows, swamps, coniferous forests, and deciduous forests.
In addition, these frogs need seasonal or semi-permanent waters to breed. While its distribution covers the neartic region, from northern Georgia, Alabama, northeastern United States, and Canada to Alaska.
Mechanism of Freeze Tolerance The study of Storey and Storey (1984) has concluded that glucose metabolites in wood frogs are produced from glycogen in the liver after exposure to temperatures below 0°C.
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Then it will spread throughout the body through the bloodstream. Apart from that, another unique discovery is that freezing in the frog’s body turns out to have an effect on various organs of the body.
Freezing the body causes dehydration of the body’s organs and the water content will return when thawed with less damage to the tissues. Decreasing water content in the frog’s body also causes an increase in cryoprotective metabolites, such as glucose.
Under natural conditions, the Alaskan wood frog goes through several freeze-and-thaw cycles before remaining frozen for the winter.
Meanwhile, in this freezing mechanism, a moderate concentration of urea has a positive effect on stabilizing membranes, macromolecules, and even reactive oxygen species (ROS). Meanwhile, antifreeze glycolipids stabilize cell membranes, and prevent ice from diffusing into the cytoplasm and recrystallizing.