Friday, March 25, 2011

The Oarfish Omen


A week before the earthquake and tsunami hit Japan, an omen washed up on its beaches. The appearance of the oarfish, a ribbon-like, deep sea fish has long been perceived as a warning that seismic activity is on the way. This fish has become a feature of speculation as to whether they can be used to predict an incoming earthquake.

There are many news reports that speculate on the issue, as well as impressive photos of this critter, which can reach lengths in excess of 50 feet.

The important message here is that so little is known about the habits, breeding, biology, and ecology of these fishes – and deep water species in general. It is difficult to say what they are reacting to – small tremors signaling a larger quake to come, poisonous gases released by shifting tectonic plates or perhaps water temperatures affected by subtle movements in these plates. So little is known about deep water fish species due to the difficulty involved in studying them in their natural environment. They do not survive long (or act erratically/unusually) in shallow water, making it difficult to glean anything about their behavior based on these shallow water sightings. Their natural environment, depths below 1000 feet, is the place to study them, only possibly by using submersible or Remotely Operated Vehicles (ROV’s) but these tools are very expensive and not very numerous.

It is estimated that we have only described about a quarter to half of the species in the deep oceans. Who knows what lives down there and what sort of interactions they have with their deep water environment, as well as what sort of future events they may be able to sense before we know anything about them?

It is also interesting that local folklore (dismissed or ignored by many in the scientific community) says that these fish appearing in shallow water signal not only an earthquake, but also a good catch! These two are likely related in that tremors or earthquakes will scare or force deep water fish into the shallows.

Wednesday, August 22, 2012

Molecular Analysis Confirms Morphological Analysis

The Aug. 6 edition of the Proceedings of the National Academy of Sciences  included a large-scale analysis of bony fishes using DNA sequencing. One of the major conclusions is that tarpons, eels and their relatives (Elopomorpha) is the sister group (branched first) of all living teleosts.

Gloria Arratia, research associate in ichthyology, first published this idea in 1997 (see reference 11 in the PNAS paper). Her conclusion was based on morphology. In short, molecular analysis  confirms a careful morphological analysis conducted about 15 years ago. More interesting is the fact that Gloria’s results were not widely accepted because the dominant figures in the field had championed the idea that the Osteoglossomorpha (mooneyes and bonytongues) were below the tarpons and eels on the tree. This inhibited some other ichthyologists from accepting Gloria's findings, in spite of the fact that she had the evidence and presented it clearly.