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Everyone knows what a pteropod is, right? Well, not quite. When I participated in NMNH’s Scientist Is In program a few months back, I talked to 262 people, asking them if they knew why pteropods were important to ocean ecosystems. Only two people had HEARD the term “pteropod”, and they weren’t sure what it referred to.
It’s ok though, since even the scientists studying pteropods don’t necessarily know which pteropod is which and what pteropod is what. Yikes!! That’s where I come into the picture. I started a post-doctoral project with IZ curator Karen Osborn in the fall of 2012 to determine species delineations in this group. I came in knowing only the basics about pteropods: they are gastropods (= snails) with a reduced or absent shell and spend their entire lives in the water column of the oceans. They get their name from the modification of the typical crawling snail foot into flapping wings (“ptero” = wing, “pod” = foot). All species are quite small, typically a few centimeters long, but they are very numerous, so form an important part of the ocean food-web.
I knew that the taxonomy of this group was a bit of a mess and hoped to use molecular genetics in concert with morphological information to assign individual pteropods to species. The Pteropoda are currently divided into the:
Euthecosomata – have shells!
Pseudothecosomata – have gelatinous (pseudo)shells!
Gymnosomata – have no shells!
Since a blog post is not the place to get into the gory details of what I have learned so far, I’m just going to share some images of a pseudothecosome that is new to science. In truth, we have been seeing this species for several years with a remotely operated vehicle (ROV) sent down to ocean depths below which SCUBA divers can safely go. This particular species has been spotted from about 450 – 1200 meters!! While it is most closely related to members of the Peraclidae family, and may belong in the genus Peracle, my genetic work indicates that this species is quite different from the few other species in this family.
These animals float or slowly sink in the water column, intermittently feeding and swimming. When feeding they hold the wings out to either side of the body and secrete a mucous web to which particles in the water column stick to. Every once in a while they pull this web full of gunk into their mouth and digest what they have caught. If they are disturbed by a predator while feeding, they will abandon the web and swim around erratically, spinning and twisting to avoid capture.
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