Iodine & metamorphosis

I was looking for Iodine and Ear Infections and came across this article. Lack of Iodine may be linked to lack of metamorphosis. The second to last paragraph was interesting about their sensitivity to toxins in the water.


http://hoglezoo.org/animals/view.php?id=71


Tiger Salamander
(Ambystoma tigrinum utahensis)

Range:
Most of the United States (not Appalachians, New England or far west), southern Canada and eastern Mexico

Habitat:
Varied, almost any location with water. includes semi-arid sagebrush, damp mountain forests, and meadows. Sea level to 10,000 feet.

Characteristics:
Long bodied amphibian which retains tail as adult in contrast to frogs. Smooth skin is kept moist by secretions of mucous glands. Front feet have 4 toes, rear have 5; tubercles on soles of feet. Color and sub-species: Some over-all olive, gray or dark brown; others striped, blotched or spotted.

Tiger salamanders live 10-16 years if they manage to escape predators. Other species of salamanders may live up to 50 years.


See what other animals are native to Utah.
Behavior:
Most tiger salamanders are typical amphibians. The larvae are aquatic. They are half an inch when they hatch and have large feathery external gills. They soon develop legs, but it takes 4 months or more for them to grow to 4 inches, lose the gills, and develop lungs. At this stage metamorphosis is complete and they become terrestrial. Some larvae, however, are neotenous, meaning metamorphosis never takes place probably due to lack of Iodine in the water. Remaining in larval form, they reach sexual maturity and grow up to 14 inches long; they retain gills and never develop eyelids as do terrestrial adults.

Tiger salamanders are wide spread but rarely seen because adults spend most of their lives underground. They often occupy rodent, tortoise or crawfish holes, or burrow into soft dirt. They hide in cool, shady, moist places under rocks and logs and in damp cellars. Due to their burrowing habits, species of this family (Ambystomatidae) are called Mole Salamanders. They are nocturnal and may sometimes be seen at night after a heavy rain, especially during breeding season. Moisture is essential. They do not drink, but absorb water through the skin while sitting in puddles, in wet mud or sand, or by flattening their bodies on dew-covered rocks. Unlike reptiles, the skin does not retard evaporation. Loss of moisture during drought can be fatal. When air is dry and it is above 90 degrees (and also when it is below freezing) they hole up in damp areas well below the surface and become torpid.

Skin is shed in pieces or in one big piece. This skin usually is eaten, but some-times it is found stuck on water weeds.

Salamanders are voiceless. Despite lack of visible eardrums, they can hear. Eye sight is good, but they probably use the sense of smell more in finding food and in locating a mate.

Reproduction:
For mole salamanders, it usually takes about 2 years to reach sexual maturity. Prompted by rain soon after ice is gone in the early spring, tiger salamanders emerge from burrows and migrate overland. Large groups gather in fishless ponds and temporary pools to mate. Males arrive first. A male nuzzles a female as she floats above him. This stimulates him to deposit spermatophores (jelly like sacs of sperm the size of pushpins) on the bottom of the pond. The female takes the sacs into her cleoaca; the jelly-like eggs are fertilized as they pass out of her body when she lays the eggs. She attaches small clusters of the colorless eggs to under water plants or debris. It takes 2 weeks or more (depending on water temperature) for them to hatch. In the north and at high elevations, eggs are laid March to June; in the south, between December and February. It is difficult to tell the sex of a salamander or identify the species except during breeding season. At this time, color changes occur and courtship rituals (which are different in each species) may be observed.


Interesting Facts:
Amphibians are considered indicator animals because they are sensitive to water quality and pollutants. Scientists can determine the of an ecosystem by the amount of amphibians found. The more the amphibians, the better the environment.

Conservation Connection:
Amphibians are an important part of the environment and should not be removed from the wild. They help keep insect populations down by consuming larvae as tadpoles and insects as adults. They also provide a source of food for larger animals.