Most animals we study have adult-like bodies early in their development. But researchers at Stanford’s Hopkins Marine Station have found that certain marine worms live for months as little more than a head.
Researchers at Stanford University’s Hopkins Marine Station found that certain marine worms go through a prolonged phase with little more than head. The study suggests that many animals in the ocean likely share this trunk-less stage, known as indirect development, and it may even shed light on the biological development of early animals.
Indirect development is the most prevalent developmental strategy of marine invertebrates and life evolved in the ocean. This means the earliest animals probably used these kinds of strategies to develop into adults.
For this study, researchers selected Schizocardium californicum, a species of acorn worm and indirect developer in the Hemichordata phylum
After spending months perfecting the rearing and breeding techniques needed to study these worms, the researchers were eventually able to sequence the RNA from various stages of the worm’s development. They did this in order to see where specific genes are turned on or off in an embryo.
They found that in the worms, activity of certain genes that would lead to the development of a trunk are delayed. So, during the larval stage, the worms are basically swimming heads.
As they continue to grow, the acorn worms eventually undergo a metamorphosis to their adult body plan. At this point, the genes that regulate the development of the trunk activate and the worms begin to develop the long body found in adults, which eventually grows to about 40 cm (15.8 inches) over the span of several years.
Even with such a fascinating result, this research is only the beginning of the Lowe lab’s examination of indirect developers. These worms will never tell us about human diseases, unlike work with stem cells or mice, but they could reveal the intricacies of how life works for many organisms beyond the model species that we’ve studied so heavily. They may also show us how life in general came to be what it is today.
Next, the researchers want to figure out how the acorn worm body development delay happens. They also have begun to sequence the genome of S. californicum.