Sexual Reproduction

Asterias rubens is a dioecious species with a breeding season from February to April. Fertilization, as for most echinoderms, is external. Females release many eggs and males release their sperm into the water in hope that the gametes will unite to form a new individual. It has been estimated that a single female measuring 140 mm in diameter can produce 2.5 million eggs!

Once the eggs have been fertilized, bilaterally symmetrical larvae form. The larvae are free swimming and free feeding. The larvae have two ciliated bands and many flexible arms. The larvae stay in this larval form for approximately 87 days after fertilization. Then they settle and go through a complicated set of metamorphosis phases to develop into their adult, pentaradially symmetric forms.

Asterias rubens has a life span of 5 to 10 years and is considered mature after 1 year.

Regeneration

One of the unique abilities that echinoderms possess, the class asteroidea in particular, is their ability to regenerate. This process can actually be considered another form of reproduction because it can result in two identical organisms. If a sea star has part of their body eaten or cut off, it will be able to grow that section of its body back. Also, the section that was separated from the original sea star can also grow into another individual! The only catch to this form of reproduction is that at least part of the central nerve ring needs to be connected to the arm that is growing back.

Send questions or comments to richards.mic2@students.uwlax.edu