30 Million Year Old Fish Fossil Reveals Evolution of the Sucker

First Posted: Jul 26, 2013 10:59 AM EDT

There are some strange creatures on Earth, especially when it comes to our world's oceans. Now, paleontologists have uncovered another bizarre species. They've discovered a 30 million-year-old fossil of a fish with a sucker on its back that could reveal the origins behind the unique feature.

Fish that possess suckers to latch onto other species aren't all that unusual. For example, remoras have suckers on the tops of their heads in order to hitch a ride on sharks, whales or turtles during oceanic journeys. Yet researchers have often wondered how these suckers evolved. It's possible that they developed in a similar way to fins in normal fish, but researchers weren't sure.

This new fossil, though, may answer that question. The fish actually falls outside the branch on the evolutionary tree occupied by all living remoras. It therefore preserves primitive aspects of the shape and construction of the adhesion disc, the sucker, not found in modern remoras. The sucker was much shorter than the disc in living remoras and had fewer segments, for example.

"The remora sucker is a truly amazing anatomical specialization but, strange as it may seem, it evolved from a spiny fish," said Matt Friedman of Oxford University in a news release. "In this fossil the fin is clearly modified as a disc but is found on the back of the fish. It enables us to say that first fin spines on the back broadened to form wide segments of a suction disc. After the disc evolved, it migrated to the skull, and it was there that individual segments became divided in two, the number of segments increased, and a row of spines were developed on the back of individual segments."

The findings not only show how this sucker might have evolved, it also shows how one fish species might have diverged from another to assume the very different body forms seen today. In addition, the research reveals a little bit more about how very strange ocean animals can look and be.

The findings are published in the journal Proceedings of the Royal Society B: Biological Sciences.

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