With the conquest of many infectious diseases, the degenerative dis- 
eases of old age have become increasingly important and research on 
the aging process is rapidly becoming more sophisticated. Because 
some marine organisms reach old age in a few hours, whereas others 
have long lifespans or reproduce asexually and hence are virtually 
immortal, marine organisms are valuable for studies on the processes 
of aging in nature. 
The value of biochemical studies on the great diversity of marine 
plants and animals is indicated by the isolation of chemicals that have 
antiviral, antimicrobial, cancer-inhibiting, nerve-blocking, or heart- 
stimulating properties in laboratory experiments. Some of these chem- 
icals have potential pharmacological value, as shown by biotoxins from 
poisonous shellfish and pufferfish that are 200,000 times more power- 
ful in blocking nervous activity than drugs such as curare presently 
used for this purpose. Such powerful chemicals are obviously import- 
ant tools for neurologists who are elucidating biochemical events re- 
sponsible for nerve and brain activity, and offer promise of applica- 
tion as useful drugs. 
The number of chemicals that may be found by intensive analysis of 
marine organisms is well illustrated by recent studies on sponges, one 
of the most primitive animals. Sponges produce at least 15 different 
types of sterols not found in higher animals, including man. By 
studying unusual sterols in sponges, we may acquire a better under- 
standing of the role of related sterols in man. In addition, investiga- 
tions of sponges unexpectedly revealed a unique material, an arabinosyl 
nucleoside, which may have practical importance in that it is 
apparently highly effective in treatment of certain virus infections and 
leukemia in laboratory animals. Other products from sponges also 
show a broad spectrum of antimicrobial effects. 
Many sea cucumbers, starfish, and their relatives produce highly 
toxic mixtures of steroid glycosides, a group of chemicals that includes 
the powerful cardiac drug, digitalis, which is obtained from a ter- 
restrial plant. Steroid glycosides from these marine organisms have 
suppressed growth of several different kinds of tumor in experimental 
animals and may provide leads toward the chemotherapy of malignant 
tumors. 
The list of pharmacologically active substances extracted from 
marine organisms is expanding as more investigators enter this 
virtually untapped field of research in natural products. With de- 
velopment of biochemical analyses and refined techniques for culti- 
vating many marine organisms that produce chemicals which may 
prove to be of medical importance, the time is now ripe for intensified 
research in marine biochemistry and pharmacology. Drugs are now 
derived primarily from terrestrial plants and bacteria or are synthe- 
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