Ichthyology

Friday, March 25, 2011

The Oarfish Omen

Oarfish

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. 

—Ed

Wednesday, September 7, 2011

Waste Not, Want Not

fish

Like any good ichthyologist, I keep saltwater fish.  When I lost a Banggai cardinalfish recently, how did I deal with this tragedy? Not by flushing it or starting a pet cemetery, but by turning that loss into a gain for the Biodiversity Institute's Ichthyology collection. 

It is true that aquarium fish make less than ideal specimens.  It is impossible to get accurate, reliable information on the natural habitat, behavior, distribution, and population structure of such a specimen.  However, for large-scale genetic studies, a specimen without such data can still provide valuable insight into the evolutionary relationships among fish species.  Likewise, we can gain important morphological information to further inform our ideas on the evolution of structures like jaws and tails.

So how does a fish reach scientific immortality after passing on to the great aquarium in the sky?  First, and not surprisingly, it's important to get the fish into the freezer as soon as possible to keep it from decomposing (genetic material starts to break down quickly as the fish decomposes).  When we are ready to process the fish, we first take photos of it, since preservation often causes bright colors and patterns to fade. Then a small piece of muscle is taken from one side and added to our tissue collection--this leaves the other side of the fish intact for morphological studies.  We then inject the fish with formalin and store it in alcohol, or clear and stain it.

While at first blush this may seem perverse, my cardinalfish now lives on as frozen tissue and fluid specimens, where it will provide valuable genetic and morphological information for researchers and students.  I know I would much prefer that to being flushed.

Saturday, May 29, 2010

Introducing Hannah Owens

Hannah OwensHannah Owens is an Ichthyology graduate student at the University of Kansas in the Biodiversity Institute.  She is particularly interested in the role of climate change in the evolutionary history and biogeography of fishes, especially cods.  Hannah will be travelling to Kangerlussuaq, Greenland for a week as part of KU’s Climate Change, Humans, and Nature in a Global Environment (C-CHANGE) National Science Foundation Integrative Graduate Education and Research Training (IGERT) program.  She and her fellow trainees (in diverse disciplines ranging from sociology and anthropology to history and engineering) will be investigating the multifarious effects of climate change in the Arctic.