Biology Reference
In-Depth Information
dots and larger, black-ringed red spots along the back. The underside is colored with yellow in varying
shades, sprinkled generously with tiny black dots. The tail, which constitutes about 40 percent of the
newt's total length, is keeled— that is, there is a thin, soft ridge running the length of the tail on both
the upper and lower sides.
Life for the red-spotted salamander begins during the spring in quiet water, sometimes in a pool or
pond that eventually dries up in late summer, although not early enough to kill the newt's completely
aquatic larval stage. The advantage to the newt of such temporary pools is that they contain no fish,
which are major predators of both larval and adult newts in permanent waters. Adult newts, though
mostly aquatic, are capable of migrating across land to reach permanent pools if their more temporary
breeding pools have dried up.
After mating, the female newt lays her eggs, which are attached to the stems or leaves of either
aquatic or temporarily submerged vegetation. For this reason, newts greatly prefer waters that contain
abundant plants, since these serve both to hold the eggs and to protect the adults from predators. There's
a wide variation in the number of eggs laid by female newts; some lay fewer than a hundred, while
others may deposit nearly five hundred.
Depending somewhat on water temperature, the eggs hatch in about a month. The tiny larvae have
keeled tails and feathery external gills located just behind the head. This larval stage is exclusively
aquatic, totally dependent on water to provide it with oxygen and sustenance. Newts in all stages are
carnivorous, and the larvae eat a wide variety of small fare. These include tiny crustaceans and snails,
larvae of insects such as mosquitoes, and water fleas.
The newt larvae continue to grow and develop throughout the summer. Then, just before the onset
of autumn, metamorphosis takes place. The gills gradually disappear, the tail loses its keels, and the
smooth, slippery skin becomes rougher. At last the young newt is ready to enter the second stage of its
life and leave the water for dry land.
Now let's switch to an entirely different scene. Imagine going for a walk in the summer woods during
or just after a rain. There you're likely to encounter small creatures that, like the newt, look somewhat
like tiny alligators; in fact, they bear considerable resemblance to a newt in size and shape, yet they lack
the keels on the tail and are colored red or orange. This is the red eft, which changed from drab brown
to red or orange just before it left its aquatic habitat.
Who would think, looking at this often brightly colored forest dweller, that it was the rather drab
aquatic newt? Logically, one would assume it was an entirely different species, but in this instance logic
would be wrong. After its gills disappear and its lungs develop, the young newt, now officially an eft,
or red eft, usually waits for a rainy night in late summer or early autumn. Then, forsaking the aquatic
world of its natal pond or stream, it sets forth to seek nearby forest land.
Once ensconced in its terrestrial habitat, an eft spends much of its time hiding in cool, damp
places—beneath logs or sticks, under leaves, burrowed under rocks, and similar places. From such
places of concealment, the eft emerges at night to feed on the smaller sorts of spiders, snails, worms,
caterpillars, and other invertebrates. On dark, rainy days, however, efts emerge in daylight hours to for-
