Notes:Poecil{{{ostomatoida)
While the sedentary sea squirts look like lowly creatures, many believe them to be the ancestors to vertebrates. Unlike the adult, the larvae are mobile and swim using muscular arrangement and skeletal support rod (notochord) seen in lower vertebrates. The key concept is that a tadple larva similar to the one pictured may have developed sexual maturity and eventually evolved into primative fish.

The tadpole larvae of most local species have a brief planktonic phase, often of only a few days, before they settle on the bottom and to become sea squirts. Their primary purpose is to find a new place for the next generation to live, and they are very selective about where they settle.

Collected by: Bill Johnson and Dennis Allen, Goucher College.

Photographed by: Bill Johnson, Goucher College.