To Bob Avent, Peter Whipple, and the other Conchlers,
 
Thank you for your support. I was speaking off the top off my head, and
responding to Art Weil's comments, which I quote below.
 
Dr Walker;-
    I rather like your quote of 100,000 species (give or take a few
hundred). The number is nice and round. I also appreciate the
proposition that many species are so far undescribed and undiscovered.
 But I doubt if the undiscovered species living in deep marine waters
will amount to as many as live in shallow biomes. There's not as much
to eat down there. And there probably is more open space for species
to spread out. I'm sure that many undiscovered species live in the
great rain forests;---but again, their numbers must be restricted
only because we have spent a lot of time looking for them already.
      Art
 
It's hard to address Art's comments in less than book length. Thanks for
providing the references!
 
I don't have any handle on the diversity of deepsea mollusks in terms of
hard numbers.
 
As Peter Whipple pointed out privately, specialization of diet is another
important factor in the proliferation of new species in many environments;
however, my impression is that this is not as important in the deep sea as
in tropical forests. Many deepsea creatures are rather broadminded about
diet. Gut contents seem to indicate that many of these animals will eat
anything that will fit into their mouths. Maybe there isn't enough to eat
in the deep sea for animals to be choosy. I'm waiting for this
generalization to be shattered by additional facts, of course.
 
What is more common in the deep sea is that the animals have specialized in
finding different ways to gather and eat food--different behavior and
different jaws, teeth, appendages, etc. You should see how many weird
appendages the polychaete worms alone have developed!
 
Yes, in the early 80's I was working on deepsea bioturbation, or deepsea
ichnology, based mainly on (1) bathyal boxcores and photos from North San
Clemente Basin, about 50 miles west of San Diego, California; (2) bathyal
and abyssal hydraulic piston cores from the world ocean; and (3) previous
literature. The ideas being cast about then (and now) were exciting,
because for a long time the deepsea floor had been thought to be drearily
homogeneous, and it's not. One of the reasons for this was that the much
more heterogeneous bathyal realm (including the continental slopes) was, at
the time, grossly undercollected compared to the abyssal realm (including
the abyssal plains). Of course, the abyssal realm is much larger than the
bathyal realm. I'd love to work on deepsea cores and photos again, but
funding has been drying up for this sort of thing for years.
 
Unfortunately for those who study the history of life in the rocks, it
turned out that most of the diversity of burrows (or lebensspuren) is lost
in the ordinary course of events. The diversity of burrows is highest at
and near the surface of the seafloor, but these burrows tend to be reworked
and destroyed by more deeply burrowing animals. The end product is usually
a sediment that has been burrowed over and over by the same few types of
animals. The shallow burrows can be preserved where a catastrophe has
buried them suddenly, e.g., under a turbidite, ash fall, low-oxygen
sediment, etc.
 
So, Bob, what's your line of work in the deep sea?
 
Andrew K. Rindsberg
Coeditor, Ichnology Newsletter
Geological Survey of Alabama