DNA can unite species that were thought to be different. Scientists believed these Sea Stars to be two different species when first discovered. Further studies of their DNA revealed that they were actually different life stages of the same animal.
Sequencing the DNA of organisms often allows you to tell them apart and has led to many discoveries when people thought single species were present in a particular place, but DNA told them there were multiple. You probably have heard of the fact that people now think there are several species of giraffe and things like that.
Well, sometimes the opposite happens. These two sea stars you see in front of you here were thought to be two different genera. These are much higher levels in the taxonomic hierarchy than species are. They’re so different that people really classify them in different groups. But you never see small ones of the big guy, or big ones of the small guy, and if you are really observant you can look into the small guy and you never find gonads in it, meaning that they are all juveniles. So some people decided that maybe there’s something else going on here and these could be stages in the growth of a single animal. We tested that with DNA and found that they are indeed the same animal and as a result these two species now have become one.
Curator, Invertebrate Zoology
Florida Museum of Natural History
Cryptic Sea Stars
Adult Sea Star (Choriaster granulatus,)
From Bokissa Island, Southern Pacific, 2005
Juvenile Sea Star (Choriaster granulatus)
From Guam Island, Western Pacific, 2003