#salpida

For the salp, sex is less of an immutable part of their biology and more like a hot potato. In their aggregate stage, these invertebrates attach together in chains. When an female chain has been fertilized by a male chain, each member will give birth an asexual offspring called an oozooid, which can later release tens of thousands of young which will grow up to aggregate together again. In the meantime, after giving birth the original fertilized aggregate salp becomes male, and will seek out a female to mate with.

Twin-sailed salp (Thetys vagina)

The Salp Lifecycle

a chain of chains

As you may or may not know a salp is a type of planktonic tunicate belonging to the order Salpida. Salps unlike their sea squirt relatives are free moving and move through the water by pumping water through their body. What really makes salps stand out is their unique two-generation lifestyle. The first portion of the salps life is a solitary one where the animal is simply an asexual barrel shape called an oozoid. The second stage called an aggregate occurs when an oozoid reproduces. When said oozoid reproduces the second animal remains attached to the other forming a blastozooid, these two animals will swim and feed and reproduce with each other. Eventually these paired individuals turn into a great chain of hundreds of salps. Unlike the oozoid form the chain of blastozooids reproduce sexually and create oozoids that will eventually form a chain of their own.

Further Reading