Is it possible for somebody to provide a nice explanation of all the tarantula ages? I read alot about 1st instar then juvie and mature male/female but still in the dark?

Thanking you in advance!
Dimitri

Instars, Embroyology, and development page 38-40 TKG Revised edition of 2009 As reference.

The lifestyle changes and form of immature individuals of many arthropods is known as instars. i.e. growth
With each molt their growth and development proceeds, and each stage consist of traits not present in the previous or applicable to the present. This means that their is a certain amount of molts between a nymph and a mature specimen.

This naming of these stages are known as instars.

An instar is defined as the stage or state of development between molts(Rupert et al., 2003) or an intermolt stage in the development of an arthropod(Lincoln and Boxshall, 1987)

Because Tarantulas do not change appearance or lifestyle during their postembryonic development as is the case with many insects, it is difficult to to determine the precise instar beyond the first two or three.

The standard to use here would be the one of M.F Downes laid down in 1987.

This states, that the female lays an egg. If the egg is fertilized, and develops, it sheds the chorion(shell in layman's terms) This is considered as hatching. Because the chorion is not manufactured by the embryo, it is not considered as the baby spider's skin.

Therefore this cannot be considered as eccdysis, and the cast of chorion not an exuvium(molt).

After this, the spider is known as post-embryo.(eggs with legs) The spider is using the last nutrients from the egg, can move it's appendages, but not move around. As this was not a true molt, the term instar is not used here.

Once the spider molts then, the nutrients are depleted and a proper exoskeleton formed, the following molt is considered a true molt, and because of the fact that it is the first true molt with true exoskeleton, the spider is now in its 1st instar.

Baby and spiderling are not reserved for particular stages in the development, but is used by as hobbyists to describe the spider.

Some species only start to crawl about in the 2nd instar, and actively feed on siblings. They start to take the appearance of a fully functional tarantula at about the 3rd or 4th instar.

Beyond that to ultimate molt is a rather grey area at present and more research is required, with well documented processes and results.

Ultimate molt refers to the male reaching sexual maturity, where the tibial apophysis become visible, his legs seems longer and the pedipalps develops into emboli. (This looks like boxing gloves. This is the sexual organs that introduces the sperm to the female.)

I hope this sheds some light and answers your question Dimitri.

TH