Genomes of two marine worms have been sequenced. The act has led to better understanding on how gills have evolved into pharynx, which let humans perform acts like bite, chew, swallow and speak. The genome sequencing has been done of two acorn worms that live in burrows in shallow water.

Acorn worms are the first genomes of hemichordates having similarities to the first animals that have evolved pharyngeal. These animals led to the rise of chordates, the animals having backbones and hollow nerve cords.

One of the study researchers, Daniel Rokhsar, said, "The presence of these slits in acorn worms and vertebrates tells us that our last common ancestor also had them, and was likely a filter feeder like acorn worms today".

John Gerhart, senior author of the report, said acorn worms are marine invertebrates that are very different chordates. But around 70% of human genes have counterparts in the acorn genes. For past 15 years, Gerhart has been studying the acorn worms, especially Atlantic species Saccoglossus kowalevskii.

It was 10 years back that Gerhart suggested to conduct genetic sequencing. Gerhart thinks that in order to know about characteristics that the common ancestors had, it is vital to compare the development and genomes of humans, chordates with the hemichordates.

The researchers found that the acorn worm has many pharyngeal slits, which allows it to filter seawater in order to capture nutrients, algae and bacteria prey.