The genome of a sea urchin is surprisingly similar to that of humans, say researchers who found the animal has a complicated immune system that could shed light on human diseases.

The California purple sea urchin, known scientifically as Strongylocentrotus purpuratus, is a spiny, pincushion-shaped sea animal.

The sea urchin shares many of its genes with humans.
(Copyright Alexandra Eaves)

It shares 7,077 of its 23,300 genes with humans, researchers report in Friday's issue of the journal Science.

The findings mean the sea urchin is more closely related to humans in genetic terms than other invertebrate models such as the roundworm or fruit fly. The embryo and larvae of sea urchins offer scientists a simple model to study how genes interact.

About 979 of the sea urchin's genes are for sensing light and odour, although scientists don't know if the blind creatures use them.

"Nobody would've predicted that sea urchins have such a robust gene set for visual perception," Gary Wessel, a Brown University biology professor and member of the Sea Urchin Genome Sequencing Consortium, said in a statement.

"I've been looking at these organisms for 31 years, and now I know they were looking back at me."

Goldmine of information

The sea urchin also showed an elaborate immune system that may help it live more than a century, as well as genes linked to the sense of taste, hearing and balance.

The study could help scientists understand the evolutionary origins of our immune system, said study co-author Jonathan Rast, a scientist in Molecular and Cellular Biology at Sunnybrook Research Institute and a professor of medical biophysics at the University of Toronto.

"Genomics has completely revolutionized the ability to look at immunity in invertebrates," Rast said. "For the sea urchin and other invertebrates, this means that after decades of inefficient searching, we suddenly have our hands on a goldmine of information."

In the long term, the results could help researchers to understand normal immune cells and how they go awry in cases such as leukemia or immune disorders, Rast said.

Rast's research was funded by the Canadian Institutes of Health Research, the Natural Sciences and Engineering Research Council of Canada, the Canada Foundation for Innovation, and Ontario Innovation Trust.