EVOLUTION IN THE DEEP SEA

ORIGIN OF DEUTEROSTOMES BACKGROUND

EXTREME LONGEVITY IN THE DEEP SEA  

There are deep-sea worms that can possibly live longer than a hundred thousand years.  I became aware of this because of my interest in factors responsible for extreme longevity.  I developed that interest from my (1956-1963) doctoral research on a Tasmanian isopod crustacean that takes three years to reach maturity.  A Michigan species from a related isopod suborder can do so in three months.

 

There are several categories of factors that are responsible for extreme longevity and/or life cycle stage duration differences.  Factors making the deep-sea worm live for thousands of years include.

                Genetics.  This factor is unknown for the deep-sea worm, but is certainly important.  We know insects such as the aphid can produce a generation in a few weeks or less, whereas some cicadas require seventeen years.  Conclusion: the genetic factor can be responsible for great longevity differences.

                Temperature.  In the deep sea temperatures are close to four degrees centigrade year around.  At sea level, temperatures can be more than twenty degrees centigrade higher year around in the tropics.  Many biochemical reactions used by living creatures double in speed for every ten degrees increase in temperature.  The bullfrog may take three years to mature in the northern part of its range, but only need a year in the southern part.  Conclusion: Temperature can be responsible for over two doublings of longevity in the deep sea, over a four-fold difference.

                Extreme pressure.  For partially unknown reasons life processes in the deep sea are greatly reduced.  Depths of 6,000 feet are associated with a 99% reduction of metabolism of bottom communities.  At the pressure of depths beyond 21,000 feet a deep sea bacterium showed a dramatic drop in respiratory rates although other environmental factors were the same.  Conclusion:  abyssal depths could be responsible for a thousand-fold difference in longevity.

                Ecological factors.  These act on the genes through natural selection to make great differences in longevity adaptive to the environment of the organism.  In the comparison I made of Tasmanian and Michigan isopods the magnitude was more than ten-fold within a similar temperature regime.  Conclusion: ecological factors of low food supply, low predation, and stable environment could select for genetics leading to a more than ten-fold increase in longevity.  The pressure and temperature differences noted previously can be multiplied and the result multiplied by this ten-fold increase to make an enormous potential difference for increased longevity of abyssal organisms.

DISCUSSION

Evolution could be so slow in deep sea organisms that ancestral forms could survive relatively unchanged while descendants migrate to surface waters and change greatly into new groups.  Known examples will be discussed eventually, if I live long enough.  But the major one making revision of the tree of life, as envisioned by my peers, necessary is one of the themes of my 2010 unpublished book manuscript (Evolution Insights).  Parts of it may be condensed in future postings.  The next evolution posting is expected to explain how major errors have been made in proposed evolution of major groups because my peers were not aware of the longevity impact suggested above.

EXTREME LONGEVITY IN THE DEEP SEA, was first implied in my 1968 paper (see references below.  It was later treated on pages 717-732, Chapter 14, of Engemann and Hegner, 1981, Invertebrate Zoology, 3^rd edition, Macmillan Publishing Co., New York.  My peers tend to ignore things that are not in major journals, their specialty journals, or monographs.]

Some starting point references, for those reluctant to take my word for it, are:

Brooks, William Keith.  1915.  The Foundations of Biology.  Columbia Univ. Press, New York.  339 pp.   Comments on - the unchanging nature of Lingula (page 219), and p. 217 “the diversity of the Lower Cambrian fauna and of its intimate relation to the fauna on the bottom of the modern ocean”.  See Jablonski et al. below.

Engemann, Joseph G.  1968.  Pogonophora: the oldest living animals?  Pap. Mich. Acad. Sci., Arts, and Letters, 53:105-108.  Extreme age of individuals inferred from published data of others about tube length, probable depth in sediments, and sediment rates of accumulation in abyssal environments.

Ericsson, D. B., M. Ewing, and G. Wollin.  1963.  Pliocene-Pleistocene boundary in deep-sea sediments.  Science, 139:727-737.  Slow rates of accumulation for marine sediments.

Gadgil, Madhav, and William H. Bossert.  1970.  Life historical consequences of natural selection.  The American Naturalist, 104(935):1-24.  P. 12 “thereproductive effort increases with age”; p. 20 “the age for reproduction will tend to increase as the degree of satisfaction or the availability of resources decreases.”

Ivanov, A. V.  1963.  Pogonophora. Consultants Bureau, New York.  479 pp.  This major monograph on the pogonophorans was published prior to the discovery of their giant tubeworm relatives at thermal vents.

Jablonski, David, J. John Sepkoski, Jr., David J. Bottjer, and Peter M. Sheehan.  Onshore-offshore patterns in the evolution of Phanerozoic shelf communities.  1983.  Science, 222:1123-1125.  Fig. 1 shows older groups from shore area are now found in deeper water, older Ordovician inner shelf forms now on outer shelf, Cambrian shore forms now on slope and deeper. Consistent with comment of Brooks, 1915.

Jannasch, H. W., et al.  1971.  Microbial degradation of organic matter in the deep sea.  Science, 171:672-675.

Smith, K. C., and R. R. Hessler.  1974.  Respiration of benthopelagic fishes: in situ measurements at 1850 meters.  Science, 184:72-73.

Webb, M.  1964a.   The posterior extremity of Siboglinum fiordicum(Pogonophora).  Sarsia, 15:33-36.  Fig. 1, page 34, shows “anchor” with 17 setae bearing annulations.  This seldom recovered portion of the worm may be so because the tube portion it is in is deep in the sediments consistent with vertical orientation of the tube.

Webb, M.  1964b.  Tube abnormality in Siboglinum ekmani, S. fiordicum andSclerolinum brattstromi (Pogonophora).  Sarsia, 15:69-70.  When worm posterior protrudes through break in tube it secretes a new posterior tube portion with no annulations but is continuous with anterior portion of the tube and sealed off from old posterior portion; Fig. 1, page 69 shows it for three species. 

Yayanos, A. A., A. S. Dietz, and R. VanBoxtel.  1979.  Isolation of a deep-sea barophilic bacterium and some of  its growth characteristics.  Science, 205:808-810.  It showed rapid depression of growth beginning at depths with pressures exceeding 725 atmospheres. 

This post may have been lost or not published.  I just relocated it and as it is important to the topics I was about to address, I thought I should try to re-post it.  
Joseph G. Engemann, June 22, 2013