Most of what we know about the life history of Austin Eurycea is based on observations made of the salamanders while in captivity. While many of these observations are of the Barton Springs Salamander, some characteristics (such as courtship) are thought to be common to the whole group. Courtship behavior involves a series of steps called a “tail-straddling walk,” which is characteristic of the family (Plethodontidae) of salamanders to which central Texas Eurycea belong. In the “walk,” the female straddles the male’s tail and rubs her chin on the base of his tail as he walks slowly forward; he stops at times and undulates his tail, possibly dispersing pheromones or showing her the location of his spermatophore. He eventually deposits a spermatophore that she will pick up in her cloaca. The eggs will be fertilized as they pass through the oviduct as they are being laid. After courtship, the female may wait months or a year or more before she lays her eggs. It is not known whether multiple males sire a single clutch of eggs.
The female (white eggs are noticeable in her abdomen) follows the male, he undulates his tail, possibly showing her where he has deposited his spermatophore.
All three species are thought to lay their eggs in the aquifer below the surface (especially so for the Austin Blind, who rarely visits the surface). This is because only a few eggs have ever been found in the wild; those eggs were thought to have accidentally washed up on the surface of the spring. Egg-laying events have only been observed in captivity.
On average, a female lays 15 eggs in a clutch. The eggs are laid singly and this process can take 12 hours or more. The ova are white and are surrounded by several layers of a clear capsule that is permeable for gas exchange. The capsule protects the embryo and is sticky, which presumably allows the female to lay the eggs on rocks in flow.
This is a time lapse video of embryo development for the Barton Spring Salamander. Notice the development of the eyes, gills, front limbs, and the heart beating in the throat area. This individual developed the back limbs after hatching.
The eggs hatch in 3-4 weeks. Hatchlings are ~½” total length (snout to tip of tail), often without fully formed limbs. Juvenile salamanders become sexually mature at about 11 months (50mm total length) and grow to about 3 inches as adults. Salamanders can continue to reproduce to an age of at least eight years.