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: Rich, Exciting, Neglected Topic

JANE THOMAS ROWLAND benefit by the association but relations are not obli- gatory; he reserves the term ""for asso- ciations in which both populationsare not only bene- fited but cannot survive under natural conditions without each other (obligate symbiosis). As early as 1876 the term ""was used by Van Beneden to describe the relationship between what he otherwise called "messmates." He states, "The messmate does not live at the expense of his ; IN ECOLOGIC STUDIES of biotic factors an approach all that he desires is a home or his friend's super- through the phenomenon of symbiosis and interde- fluities" (Van Beneden 1876:1). pendence of can be most meaningful and Because true is treated extensively in Downloaded from http://online.ucpress.edu/abt/article-pdf/36/2/77/31514/4444655.pdf by guest on 01 October 2021 enlightening to the student at any educational level. many books and journals, it is assumed here that this It is my opinion that symbiosis has been greatly relation gets its due credit; so I will concentrate on neglected and underemphasized in general- symbiosis in a more narrow sense, which includes textbooks, as well as in much of the current ecologic various degrees of mutualism and commensalism, literature and the environmental studies that are so together with the relationship often called "social popular today. Many textbooks devote only a few parasitism." In social parasitism the symbiont does paragraphsto symbiosis, and these usually resort to not live in or on its host and does not receive its the most commonly used examples, leaving the im- nourishment from the tissues of its host. The social pression with the student that there are only these parasite exploits the host in other ways, few situations and that symbiosis is an exception such as stealing some of its , using it as a slave, rather than a usual occurrence in animal behavior or seeing that it incubates its eggs and raises its and in -and-animalassociations. The purpose of young. "Behavioral symbiosis" is a term used to de- this article is to encourage the presentation of a scribe associations in which the contact may not be wider selection of examples to students and to show intimate or persisting but involves certain behavioral the universal principle of interdependence of spe- patterns of the organisms involved. cies, which takes on varying gradients of what can easily be categorized as symbiosis. Importance of the Study of Symbiosis Definitions of Terms The interdependence of organisms is a most out- standing principle of , whether it is at a micro- There is considerablecontroversy as to what should scopic level and involves nutritional exchange at the and should not be classed as symbiosis. The term tissue or cellular level or involves occasional contact symbiosis (Greek, "living together") was first pro- or behavior at the organismiclevel. No organism can posed by DeBary in 1879 to refer to organisms of exist in nature without others in its environment. two living together. DeBary used as These dependencies include the need for food, habi- a representative example of symbiosis; so it is quite tat, protection,reproduction, companionship, or other logical that the most popular usage of the term refers factors or a combination of these. The fascinating to mutually beneficial relationships. However, the aspect is how different organisms meet their needs broad meaning includes all intimate associations; in such diverse ways. It is the diversity through evo- therefore symbiosis can be divided into three main lutionary adaptation that presents the student with categories: (i) mutualism, in which each partner such a variety of unusual examples. However, one receives benefit; (ii) commensalism, in which one partner (the commensal) is benefited but the host The author is assistant professor of biology, is unaffected; and (Miii)parasitismn, in which the host Paine College, 1235 15th St, Augusta, Ga. is exploited to the benefit of the parasite (symbiont). 30901. She is a 1952 graduate of Tift College Needless to say, no distinct boundaries separate and has her M.S. from Emory University. Before joining the Paine faculty she taught these associations. This fact complicates defining and at Armstrong State College, Savannah, 1953- classifying the many associations of organisms.Inter- 56, and at Augusta College, 1961-84. She actions between species may be very complex, and frequently contributes book reviews to additional terms are applied to specific relationships. Choice, a publication of the Association of Authorities differ in their usages of such terms. College and Research Libraries. Library research of the kind reflected in this paper has been a primary interest of Odum (1971:211) uses the term "" the author for the past 10 years. Mrs. Rowland's husband is to designate an association in which both populations the librarian of Augusta College.

77 does not have to search out the unique (however Other examples of cleaning activity include ground exciting this may be) to find examples of symbiosis. finches removing ticks from the skin of tortoises Every , every of and ani- (MacFarland and MacFarland 1972:632); a lark mals is well supplied with many symbionts. From pecking parasites from the back of the imouran, a the lichens on barren rocks or intestinal in large rodent of Mongolia (Pearse 1939:513); red the human body to the and in the crabs of the Galapagos Islands ticks from garden, a student can witness the marvelous inter- the leathery skin of iguanas (Simon 1970:96; Feder action of species. 1966:329); a pseudoscorpion cleaning a lizard (Feder In this day, when molecular biology is so popular, 1966:329); cleaning dung deposits from the there has been a definite decrease in interest in cer- body of a dung (Burton 1969:52); pseudo- tain aspects of natural history. This has occurred in scorpions removing mites from long-horned spite of the soaring interest in environmental biology (Dudley 1965:49; Simon 1970: 80-83); and barber and is evidenced by a relative decline in the amount grooming their host ants (Simon 1970:83). of information published on symbiosis, except in Many commensal organisms live in the or microbiology ( and the like). Be- burrows of their hosts and are cleaners or scaven- havioral symbiosis, such as is evidenced in gers, removing unwanted scraps of food, parasites, and in insects, was a popular topic in many works and excrement. The clownfish, in addition to its pro- published about 1900-1950. Some of the most thor- tective association with anemones (mentioned be- ough works are now quite dated, and there are low), has been observed grooming the tentacles of Downloaded from http://online.ucpress.edu/abt/article-pdf/36/2/77/31514/4444655.pdf by guest on 01 October 2021 relatively few books in print that deal exclusively the anemone. with symbiosis. The whole organism and its relation to its environment should still receive attention. Beater Associations Fortunately, there are periodicals that still deal with A beater, or driver, is an animal that disturbs the natural history of organisms, including the biotic small creatures as it moves about; and other animals, factors of environment; among these are Natural such as insectivorous birds, prey upon the animals History, Audubon Magazine, and Animals. flushed. Rand (1954) cites descriptions of a number of such relationships. A common example is the asso- Symbiosis Takes Many Forms ciation of cattle egrets with large herbivorous mam- mals (Peterson 1954). The carmine bee-eater uses Because there are so many types of symbiosis and the kori bustard as its beater; and, as is the case such a large number of close interdependencies of with many of these symbionts, it often rides on the different species, this paper will emphasize only five back of the beater, frequently jumping off to capture categories, which can serve to show the wide hetero- insects (Rand 1954). Pompadoured hornbills, or specific situations represented. These categories are monkeybirds, in Africa associate with guenon mon- , beater associations, keys, feeding on the insects made more easily avail- symbiosis, symbiosis for shelter or protection, and able to them (Burton 1969:36; Simon 1970:31). One social parasitism. species of African hornbill follows driver- col- umns, before which small animals are fleeing (Simon Cleaning Symbiosis 1970:32). Other birds also associate with driver ants In the study of symbiosis many aspects of animal for this purpose; for example, the antbirds (Willis behavior are observed. Cleaning symbiosis, for ex- 1973). Welty (1962:380) says the rough-legged hawk ample, involves a wide variety of organisms. "Clean- follows the Arctic fox, to feed on the mice it stirs up. ing symbiosis is defined as a relationship during In the U.S. we often see cattle accompanied by cow- which certain organisms, known as cleaners, remove birds, which gain from the association by the greater ectoparasites, bacteria, diseased and injured tissues, number of insects they are able to catch. and unwanted food particles from cooperating hosts" (Cheng 1970:26). This has been studied most thor- Pollination Symbiosis oughly in marine organisms (Limbaugh 1961; Feder Interdependence of plants and animals becomes 1966). Certain cleaner organisms, such as fish and most interesting and varied with pollination . , set up cleaning stations and have an eager Whenever a plant is dependent upon a biotic agent clientele of fishes waiting to be cleaned of parasites, for its pollination, this approximates symbiosis. Some diseased tissue, and debris. The host is benefited, plants, however, have developed such great specific- and the cleaner is rewarded with a meal of the clean- ity in the methods of pollen transfer that they and ings. On land, there are birds that accomplish the the pollinators may definitely be considered cases of same for large . The oxpecker, or tickbird, mutualism. The yucca plant is totally dependent removes parasites from its host, which is frequently upon the Pronuba moth for its reproduction; and the a rhinoceros (hence another name: rhinoceros ). moth, in turn, cannot reproduce without its host The bird, -eater, or Egyptian plover plant (Powell and Mackie 1966; Rau 1945; Riley removes and bits of food from the mouths 1892). The Smyrna fig cannot produce without of basking (Guggisberg 1972: 75-80; Henry the aid of a tiny chalcid wasp ( Bulla 1941; Cuttle 1967: 298) . 1953; Sisson 1970). Many orchids are so specialized

78 THE AMERICANBIOLOGY TEACHER, FEBRUARY 1974 that they are dependent on one species of for backs into the hole while the host is absent and lays their pollination. The bee orchid actually mimics a an egg. This may be repeated a number of times. The female bee, to attract the male. He attempts to copu- cuckoo wasp's larvae destroy the host eggs or small late with the and, in so doing, accomplishes larvae and also feed on the prey previously provided pollination. This phenomenon is called "pseudocopu- by the host wasp. There are also many genera of lation" (Faegri and van der Pijl 1971:82; van der bees that are cleptoparasites of other bees. Pijl and Dodson 1966:131-140). Another type of social parasitism found in ants Another strange adaptation to insure pollination is and in wasps involves "enslavement": the use of found in Stapelia, the starfish flower, or carrion workers of the parasitized colony as a work force for flower. It mimics the odor of carrion to attract flies, themselves. which transfer the pollen. A number of bird species practice brood para- sitism (also called parasitism). Cuckoos, cow- Symbiosis for Shelter or Protection birds, and honey guides are examples of these birds, Many arrangements for living together provide at which do not build their own nests or care for their least one partner with an element of protection. Cer- young; instead, they lay their eggs in the nests of tain hermit crabs carry anemones on their borrowed- other species of birds. The host birds then must see shell homes for the protection provided by the nema- to the incubation of the eggs and the feeding of the tocysts (stinging cells). Man-o'-war fish live among young parasites. Downloaded from http://online.ucpress.edu/abt/article-pdf/36/2/77/31514/4444655.pdf by guest on 01 October 2021 the armored tentacles of the Portuguese man-o'-war, Social parasitism is also represented by birds that for the same purpose. The clownfish among the pilfer food from other birds. Eagles may steal from tentacles of a amemone (Gohar 1934; Williams ospreys. Jaegers, skuas, and frigatebirds (man-o'-war 1950) and reportedly cannot long survive away from birds) habitually chase smaller seabirds, forcing it. Certain sea slugs (nudibranchs) feed upon the them to disgorge or drop fish they have recently tentacles of coelenterates and are able to incorporate caught. Some birds appropriate the nests of other the nematocysts into their own bodies to afford pro- birds and there lay their own eggs and raise their tection for their soft bodies (Zeiller 1971). Birds may young. associate with more aggressive or larger birds or with hymenopterous insects for protection. This is Miscellaneous Kinds referred to as a "protective nesting association." It These categories barely touch the surface of this involves many species of birds (Welty 1962:261-263; topic but should serve to illustrate how inexhaustible Chisholm 1952). Van Tyne and Berger (1959:280- are the examples. Additional aspects of symbiosis 282) give a composite classification of nesting asso- that serve well to present ecologic principles to stu- ciations. Certain shrimp and other organisms shelter dents would be insect symbiosis, including ants and within the cavity of and may be highly their "cow" , their , their guests selective as to the host species. The gall crab lives (myrmecophiles), and their slaves. Ants and their in ; it becomes permanently sealed within its gardens make an entire ecologic study (Batra host. The pearl fish lives inside the cavity of a sea and Batra 1967). Then there are the myrmecophilous cucumber. ("ant-loving") plants, such as the acacias that house ants in their hollow thorns (Hutchins 1957). And Social Parasitism there are the insects and other small organisms that Two groups of animals serve best to illustrate so- are symbiotic within pitcher plants or are associated cial parasitism: the hymenopterous insects (ants with other carnivorous plants (Jones 1921; Eisner and wasps) and the birds. Ants are highly organized 1967). This association has received very little at- socially, but from the human viewpoint they may tention in textbooks and the general literature avail- not always behave nicely. For instance, one small able to students; but the symbionts show some of ant, Solenopsis molesta, lives in the walls of nests the most extraordinary of evolutionary adaptations. of a larger species of ant and steals the larvae and Algal symbiosis, on the other hand, has received pupae of its host. "Lestobiosis" is a term used to much attention. Everyone is familiar with the com- describe the type of symbiosis in thief ants (Sudd mon lichens, each consisting of an alga-and-fungus 1967:78). Other intruders also act as thieves in ant association; but examples from almost all forms of nests. The thysanuran Atelura formicaria steals the are in some way associated with algal symbionts. food that is being exchanged between two ants. A Algal symbiosis extends all the way from associations fly, Metopina pachycondylae, steals food from a spe- with microsymbionts up through higher plant and cies of ponerine ant (Frost 1959: 254). Cleptoparasitic animal groups, even including the mammals; for (Greek kleptes, "thief") wasps are discussed by example, live in the hair of the two-toed Evans and Eberhard (1970:208-216). These wasps (Grave 1958). may steal the paralyzed prey of other wasps or may extend their activity to brood parasitism. The cuckoo The Literature of Symbiosis wasp is an example of this association. A female positions herself near the entrance of the nest of Information about many of the symbiotic relation- another species of wasp and, at an opportune time, ships is not readily found in the general biologic

SYMBIOSIS 79 literature. The search is often difficult, because the _ . 1920. Hermit crabs' little friend. Literary Digest subject-entry "symbiosis" may not be the one under 65(12):33. On crab and anemone. which a certain relationship or interdependence is . 1924. Pronuba moth. Nature Magazine 4(3):185. .1925. Luminous plant and animal companions. Lit- to be found. I have found many rather obscure asso- erary Digest 84 (9): 75. ciations simply by searching through the indexes of _ . 1937. The partnership between Yucca filamentosa, periodicals, by studying the literature cited jn lo- known also as Adam's needle, and the moth Pronuba cated references on the subject, by browsing the yuccasella. Nature Magazine 29(1):36. . 1948. Sea anemones and damsel fishes. Science indexes of all types of botany and zoology books, and Digest 24(4): 76. by searching bibliographic indexes under particular . 1956. African honey-guides. Science 123:55. headings, such as "cattle egret," "oxpecker," and _ 1958. Odd partners found in nature. Life 44(17):86. "clownfish." After 10 years of this I now possess . 1963. Animal husbandry in the animal kingdom. quite an extensive file of titles relating to interde- Time 82 (23) : 98. .1965. Nature note: farmer ants. Science News Let- pendencies of plants and animals. ter 89(9):335. Books on the subject of symbiosis range from juve- ARGO, V. N. 1965. Bull-horn acacia; Mexican ant acacia. Nat- nile literature through technical works on specific ural History 74(1): 22. relationships (monographs). Many parasitology text- ARUEGO, J. 1970. Symbiosis: a book of unusual friendships. Charles Scribner's Sons, New York. books give definitions and examples of the different BAER, I W. 1920. Ecology of animal parasites. University of types of associations; indeed, they often devote an Illinois Press, Urbana. Downloaded from http://online.ucpress.edu/abt/article-pdf/36/2/77/31514/4444655.pdf by guest on 01 October 2021 entire chapter to this topic, as in Noble and Noble BAILEY, I. W. 1920. Some relations between ants and fungi. (1961). Ecology books often devote a chapter to Ecology 1(3):174. BATRA,S. W. BATRA. biotic relationships and include many of the T., and L. R. 1967. The fungus gardens of more insects. Scientific American 217(5):112. typical examples. General-biology, zoology, and bot- BELLOMY, M. D. 1973. Blossoms in the sea. Sea Frontiers any textbooks usually do little more than mention 19(1):2. "Odd Mergers," p. 9. the topic. Books on natural history may have some BROCK,E. M. 1960. Mutualism between the midge Cricotopus examples of certain relationships, but little detail and the alga Nostoc. Ecology 41(3):474. BRUCE, A. J. 1972. that live with molluscs. Sea Fron- is given. Periodicals have a wealth of information, tiers 18(7):218. but, as I said earlier, it is not always easily retrieved. BUCHNER, P. 1965. Endosymbiosis of animals with plant micro- Popular articles on the subject are not very numer- organisms; rev. ed. Interscience Publishers, New York. ous but are frequently quite informative. Some are BULLA,P. 1941. Mystery of the fig. Natural History 47(2):97. on symbiosis in general and give a number of ex- BURTON,M. 1969. Animal partnerships. Frederick Warne & Co., New York. amples; others describe single relationships. Techni- CASEBEER,R. S., and C. L. HOGUE.1966. Hideaway for moths: cal articles on the subject are more numerous in the symbiotic relationship with two- and three-toed . area of microscopic symbionts, such as , Natural History 75(5):40. , and . Diligent searching CAULLERY,M. 1952. Parasitism and symbiosis. Sidgwick & Jackson, London. reveals behavioral of in aspects symbiosis birds, CHENG, T. C, 1970. Symbiosis: organisms living together. fishes, and other animals. Treatises on the natural Pegasus Press, New York. history or ecology of particular organisms frequently , ed. 1971. Aspects of the biology of symbiosis. Uni- include difficult-to-find information on close associa- versity Park Press, Baltimore. tions the animal or plant has with others in its hab- CHISHOLM,A. H. 1952. Strange relations of birds and insects. Nature Magazine 45(10): 526. itat. COOPER,E. K. 1963. Insects and plants: the amazing partner- When searching for the more popular articles on ship. Harcourt, Brace, & World, Inc., New York. symbiosis, I have found the following terms often CURRAN, C. H. 1941. Who was the first horticulturist? Natural used in titles: partners (strange, unusual, odd), com- History 48 (6): 60. On yucca and moth. CUrILE, E. R. 1953. $2,000,000wasp. 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SYMBIOSIS 81 another do not wish to be dentists. The dental hy- careful in this and not be too surprised to discover gienist works under the supervision of the dentist, that credit earned for qualification as a dental as- to remove stains and deposits from the teeth and sistant is usually not applicable toward qualification to apply medication to the teeth for the control of as a dental hygienist. tooth decay. These workers take and record medical and dental histories, prepare diagnostic tests for How to Learn More interpretation by the dentist, and chart conditions of decay and disease for diagnosis by the dentist. The positions discussed in this paper have been They make and develop x-ray films, sterilize instru- carefully selected from government and private ap- ments, maintain patients' records, and act as as- praisals (Bureau of Labor Statistics 1973; Ferguson sistants to the dentist. Some are employed by school 1971). Selection was based on two criteria: (i) is districts to do these tasks and to teach children the the job one that would appeal to a student interested techniques of proper mouth care and proper diet. in pursuing biologic studies, and (ii) will there be Many dental hygienists are part-time workers, but jobs open when the student completes his training, all have attended a two-year program in dental hy- within the next 10 years? giene. There are some four-year and some five-year A list of associations accrediting schools or licens- programs leading to a bachelor-of-science or master- ing qualified students can be had by sending a self- of-science degree, respectively. All dental hygienists addressed, stamped envelope to the author. must pass state board examinations. There are excel- Downloaded from http://online.ucpress.edu/abt/article-pdf/36/2/77/31514/4444655.pdf by guest on 01 October 2021 lent opportunities in the field of dental hygiene. Acknowledgment.-The photos are courtesy of St. Vincent's The dental assistant also works with the dentist Medical Center of Richmond, Staten Island, N.Y. and does much the same work as the dental hy- gienist. However, the dental assistant does not per- REFERENCES form work in the patient's mouth. A one- or two- BUREAU OF LABOR STATISTICS, U.S. Department of Labor. 1973. year course at a community or junior college is Occupational outlook handbook, 1972-1973 edition. Bulletin 1700. U.S. Government Printing usually required, as well as some typing skill. Many Office, Washington, D.C. FERGUSON, J. W. 1971. Ferguson guide to two year college dental assistants decide after a few years of work programs for technicians and specialists. J. W. Ferguson to become dental hygienists. However, one must be Publishing Co., Chicago.

81 VERRILL, A. H. 1938. Strange birds and their stories. L. C. Symbiosis... from p. Page & Co., Boston. "Strange Partners," p. 153. osis. In Audubon Nature Bulletin set NB 7 on Ecology. WADSWORTH, A. J. 1953. Study of a yucca. Nature Magazine National Audubon Society, New York. 46(10) :528. SILVERSTEIN,A., and V. SILVERSTEIN. 1968. Unusual partners: WALLIN, I. E. 1927. Symbionticism and the origin of species. symbiosis. McGraw-Hill Book Co., New York. Williams & Wilkins Co., Baltimore. SIMON, H. 1962. The study of birds made simple. Doubleday WASMANN, P. E. 1912. Ants and their guests. Smithsonian & Co., Garden City, N.Y. "Strange and Unusual Habits: Report 1912. P. 455. Partnerships," p. 75. WATTS, V. M. 1932. Orchid and the bee. Nature Magazine _. 1970. Partners, guests and parasites: coexistence in 20(3) :113. Nature. Viking Press, New York. WEBER, N. A. 1962.Insect gardeners. Natural History 71(1):45. SISSON,R. F. 1970. The wasp that plays cupid to a fig. Na- _. 1966. Fungus-growing ants. Science 153:587. tional Geographic 138 (5): 690. WELTY, J. C. 1962. The life of birds. W. B. Saunders Co., SKUTCH, A. F. 1959. Trogons and wasps' nests. Nature Maga- Philadelphia. P. 108, 109, 261-263, 377-381; passim. zine 52(9):464. WILLIAMS, W. 1950. Clownfish. Natural History 59(5):208. SLOSSON, E. E. 1924. in low life. Science Month- WILLIs, E. 0. 1973. The behavior of the oscellated antbirds. ly 19:103. Smithsonian Contributions to Zoology 144. STEP, E. 1924. Messmates: a book of strange companionships YONGE,C. M. 1957. Interrelations of organisms: C. Symbiosis. in nature. Hutchinson & Co., London. In vol. 1, Treatise of marine ecology and paleoecology, STREET, P. 1958. Animal partners. E. Ward Publishers, London. ed. by J. W. Hedgpeth. Geological Society of America, New STUNKARD,H. W. 1957. Organisms and their associations. York. Natural History 66(9):494. ZEILLER, W. 1971. Naked gills and recycled stings. Natural SUDD,J. H. 1967. An introduction to the behavior of ants. St. History 80(10) :36. On nudibranchs and coelenterate nema- Martin's Press, New York. Passim. tocysts. TEALE,E. W. 1948. Ants' camels: honeydew-producing in- ZEUNER, F. E. 1963. A history of domesticated animals. Harper sects. Natural History 57(10):456. & Row, New York. "The Origins and Stages of Domestica- THOMAS, L. 1971. Sensuous symbionts of the sea. Natural His- tion," p. 36. tory 80(7):28. TRAGER,W. 1970. Symbiosis. Van Nostrand Reinhold Co., New York. VAN BENEDEN,P. J. 1876. Animal parasites and messmates. D. Appleton & Co., New York. Plight of the Parthenon VAN DERPIJL, L., and C. H. DODSON.1966. Orchid flowers: their pollination and evolution. University of Miami Press, Air pollution is eating away at the 2,400-year-old Coral Gables, Fla. Parthenon, the glory of the Acropolis. Traffic and fac- VAN TYNE, J., and A. J. BERGER.1959. Fundamentals of orni- thology. John Wiley & Sons, Inc., New York. "Nesting As- tory fumes in Athens are not only pitting the marble sociates," p. 280. but are rusting the iron bars used in restoration.

86 THE AMERICANBIOLOGY TEACHER, FEBRUARY 1974