Starfish Regeneration

How Long Does It Take a Star Fish to Regenerate?

The actual time it takes for an arm to regenerate into an adult star fish varies. This phenomenon is regulated by both exogenous (seasonal changes, environmental stimuli)and endogenous factors (body size, humoral and nervous factors). Several studies have been done on this topic and it appears that within 6 weeks the animal has made significant growth advances in replacing the lost body parts.

I know most starfish have 5 arms but can they have more?

Starfish come in lots of different varieties, one recent count numbered the species in this class at about 1500! So, to answer your question, some starfish have more than five arms, in fact one, the Helicoilaster has 50 arms which all radiate from the central body part.

In addition to arms in multiples of five, many echinoderms have the remarkable ablitity to regenerate lost arms. In some cases, lost arms have been observed to regenerate a second complete sea star.

Source:http://science.jrank.org/pages/6450/Starfish.html