Regenerating Sea Squirts

A couple weeks ago, in my post “Growing Body Parts,” I briefly discussed the ability of some animals to regenerate damaged body parts. New Scientist reports today on an animal capable of far more dramatic growth.

Israeli scientists studying a species (Botrylloides leachi) of sea squirt found that just a fragment of a blood vessel could regrow a full, adult sea squirt. The article states

Out of 95 fragments they examined, 80 underwent whole body regeneration (WBR). Cells first grouped into hollow spheres, then cell layers in-folded and organs developed until after two weeks an adult sea squirt had grown, capable of sexual reproduction.

Sea squirts are invertebrates that live in the water. They are somewhat close relatives of us, probably the vertebrates’ closest relatives. The most recent ancestor of sea squirts and all the vertebrates (including humans) lived perhaps 565 million years ago. The vertebrates, along with sea squirts and lancelets, make up the phylum Chordata.