The key to figuring it out was to think globally, not locally.
Mystery has surrounded these tiny animals since they were first discovered in the Gulf Stream. Easily identified as sea star larvae (i.e., babies) they are some of the most abundant animals in certain plankton samples. Not only are samples “crawling” with them, but they show evidence of cloning themselves, something that was previously not known to occur in sea star larvae. Using DNA sequences scientists have searched for 30 years for a match between these distinctive larvae and adult sea stars from the Gulf of Mexico and the Caribbean.
We collected some of the mystery larvae as part of project to describe and identify the larvae living in Panamanian waters. Like the prince with Cinderella’s slipper, we initially could not find a match to our DNA sequences either. Using the Barcode of Life Database, we discovered a match to an unpublished sequence from the Indo-Pacific. No information other than the name of the scientist who generated the sequence was public, Gustav Paulay. Luckily (in this case anyway), the community of biologists working on marine invertebrates is small and I knew Gustav. After comparing the sequences, we agreed that the sequences from the Caribbean larvae match the sequences of a rarely seen sea star from the Indo-West Pacific, Valvaster striatus.
This sea star appears to range across almost all of the Pacific, but it lives deeply hidden inside coral reefs, making them difficult to find without literally taking the reef apart.
Adults have never been reported in the Caribbean, but they must presumably be lurking here, out of sight, shedding eggs and sperm into the water column to generate these famous larvae…. Or… maybe the larvae are cloning themselves, maintaining dense populations without the need for adults.
Only time (and more research) will tell.
Read our original publication at: https://www.journals.uchicago.edu/doi/10.1086/710796
Collin, R., D. E. Venera-Pontón, G. Paulay, and M. J. Boyle. 2020. World Travelers: DNA Barcoding Unmasks the Origin of Cloning Asteroid Larvae from the Caribbean. Biological Bulletin. doi/10.1086/710796
