A Brief History of Marine Invertebrate Culture | More on Gorgonians

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Online Newsletter for Reef Aquarium Propagation Research

ISSUE # 3 - page two
MARCH 1997

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A Brief History of Marine Invertebrate Culture

by Rob Toonen

Section of Evolution and Ecology,

University of California, Davis, CA.

When LeRoy first asked me about writing an article for this newsletter, I thought that he was interested in having me write an article about which I knew something. I expected to write an article outlining something about captive rearing of marine invertebrate larvae, or general invertebrate zoology. Instead, Leroy asked me to continue in the vein of recent articles in this news letter and write something about the history of marine invertebrate culture. I had never really thought about trying to cover the subject before, but figured, "what the heck, it's worth a try." I had no idea how difficult that would turn out to be. It is relatively easy to go to the library and locate dozens of recent articles in scientific journals on any topic of interest. It is quite another matter however, to track down the first reference to some topic or another.

The history of a field is generally covered by one of two types of people:
the very old, or the very well-read. I am neither. .... I am in my twenties,
so I have not been around to witness the changes in the field or remember
"the way things used to be."

The history of a field is generally covered by one of two types of people: the very old, or the very well-read. I am neither. I am not an old man. I am, in fact, I am in my twenties, so I have not been around to witness the changes in the field or remember "the way things used to be." Neither am I an historian. In fact, I must admit that I have been sorely remiss during my training as a marine biologist in paying attention to the history of the field. Sure, I've read the classic papers, and I have a decent idea of the larval biologists who have had the greatest impact on the field (the greats, like Gunnar Thorson, D.J. Crisp, D.P. Wilson and E.W. Knight-Jones are IMHO pretty much required reading). But I didn't really pay attention to who the first person to successfully culture barnacles or tube-worm larvae was, nor what technique they used. I simply haven't been around long enough to have developed a very good idea of how the field started, or how it has changed. Writing this article has been good for me, because I have probably learned as much as I am about to pass along to you. Having said that, because I am not an historian, I am certain to have missed the original work or given credit for some accomplishments to the wrong person at some point in this article. For that I apologize. I have tried to make a reasonable attempt to find the oldest references available for the culture techniques which I mention in this article, but cannot make any claims as to the accuracy or completeness of this review. You are forewarned: I hope that you will enjoy this article, but the reader should consider this historical information my opinion rather than fact. I emphasize that point because in order to write this article, I was forced to locate the oldest citation I could find in the library data base, and then work backwards (I started with that manuscript, and then looked at what papers that source cited, move back and locate those papers to find out who they cited, and so on) until I reached a "dead end." At that point I assumed that the author had done their homework, and that I had located the original article for a given technique. This is likely not to be true in at least some, if not many, of the cases (many academics have a bad habit of claiming more credit for something than they deserve), but it is the best I can do.

The first problem which researchers had to overcome
in rearing marine invertebrates was supplying adequate
amounts of food to the larvae.

The first problem which researchers had to overcome in rearing marine invertebrates was supplying adequate amounts of food to the larvae. The first techniques were, of course, natural collections of phyto- and zooplankton with nets in order to feed larvae. Caswell Grave (1902) was apparently the first person to develop a "balanced aquarium" in which larvae were reared in a tank with heavy diatom growth. Contrary to the popular belief that Jaubert originally came up with the idea to maintain "miniature balanced ecosystems" and developed the idea to use natural sand, I think Caswell Grave was probably the first person to ever develop an aquarium around the use of "live sand." Grave dredged a liter of sand from the ocean floor, and set it up in an aquarium before a large window where it was protected from direct light (direct light would likely lead to problematic warming). This led to the growth of a diatom film on the sand. He then set up 1 liter subcultures with clean water and enough diatom-coated sand from the aquarium to barely cover the bottom of a flask. Larvae were added to these smaller cultures and covered (to minimize evaporation, I would presume) before being set in front of the window again. Using this method he succeeded in raising several sand dollars (and spatangoids, but few people will recognize this group) through metamorphosis and three months of healthy post-metamorphic growth.

Although this method obviously worked to raise a few larvae, there was a fair bit of uncertainty involved, because the conditions were never likely to be exactly the same. For example, one never knew which species of diatom would grow, whether there were other organisms in the collected sand that may compete with, or prey upon the larvae, etc. Researchers wanted a method of obtaining and feeding pure cultures. The original method was suggested by Miquel (1897) and modified by many thereafter (e.g., Allen 1914; Allen & Nelson, 1910; Gran 1931, 1932, 1933; Waksman & Iyer, 1932). The basic technique involved adding certain nutrients (potassium nitrate, calcium chloride, sodium phosphate and ferric chloride) to seawater, sterilizing that enriched seawater and inoculating the nutrient medium with a single species of diatom. Others (e.g., Schreiber, 1927) pointed out that modifications of the basic recipe led to increased success with culturing certain species of phytoplankton (e.g., the addition of Potassium silicate to diatom cultures). Because sterile techniques had already been well established for bacterial research, these techniques actually predated the culture of marine invertebrate larvae, but they were not widely applied to larval culture until the 1930's (see previous references). Obtaining sterile, enriched seawater was the easy part, however. Early researchers did not have the University of Texas algal collection from which to order stock cultures of a specific species of diatom, nor did they know which species were good or poor food choices for various larvae; they were forced to use trial and error to collect unicellular algae to culture, and then determine how appropriate that alga was for culturing various animals. The methods used by these early researchers to isolate algae were simple, but turned out to be quite effective. The first was to simply look under a microscope and pick a single cell of a likely candidate alga from a natural collection of seawater. Assuming that the cell lived and started to divide, these cultures would be grown up and tested for suitability as a food item. Another method involved placing a drop of natural seawater into a large dish full of enriched sterile seawater. This drop would be well mixed, and then the dish would be kept under subdued light in an area where it could be examined with a hand lens without moving or disturbing it. As soon as colonies from the individual cells could be seen growing in different parts of the dish, a small sample of each would be removed with an eyedropper and transferred to fresh culture medium. In this way one could obtain many cells of the same species to innoculate a culture and eliminate some of the variability involved with starting a culture from a single cell.

Some fairly elaborate modifications of these methods were developed by subsequent researchers in order to eliminate as many bacteria, ciliates, flagellates and other microorganisms. For example, Schreiber (1927) suggested slowly dripping sterile water into a narrow J-shaped tube filled with a sample of natural seawater. In this way, he allowed the heavier diatoms to collect at the bottom of the J, while smaller, lighter organisms were flushed from the tube as water overflowed. Others (e.g., Allen, 1914) suggested serially poisoning (with short-term exposure to compounds such as copper sulfate) the culture in order to remove all unwanted organisms. These techniques did reduce the number of bacteria and other contaminants (as well as the diatoms of interest, unfortunately), but never seemed to result in pure cultures. Fortunately, today we have access to places like the University of Texas algal collection to simply order pure, sterile cultures of the unicellular algae which we wish to culture for our larvae. Of course there are many other suppliers (such as Florida Aqua Farms -- 33418 Old St. Joe Rd., Dade City, FL 33525 ph. 904-567-8540) that supply starter cultures, but no other supplier can touch the selection offered by the University of Texas, and this is the North American repository for every species of algae and diatom ever cultured. These other techniques still work for people who lack the resources to purchase pure cultures from a supplier, but are not nearly as reliable or repeatable for developing cultures, so one must weigh the cost against the quality of the product desired.

Well, algae are probably of less interest to most reef-keepers, so I'll move on the animals. The earliest reference to the culture of sponge larvae which I can locate is Wilson (1894). Because sponges generally have "internal" (it's not really internal, but takes place within the body -- I won't bore you with the technicalities) fertilization and the eggs are brooded within the body of the parent for some period of time prior to the release of planula larvae, Wilson simply placed reproductive sponges into a jar and collected the larvae as released. Planula larvae of sponges are well-provisioned with nutrients, and do not need to be fed, so it was relatively easy to keep the larvae until they settled and began to grow into the adult body form. The sponges were kept in culture jars, and the water was changed 2-3 times per day, leading to growth, maturations and even some embryos being produced by the captive animals (Wilson, 1907). Not bad for 1907, considering how often I get requests for people asking me how to keep their sponges alive today.

Polychaete worms (better known as "bristle worms") have been a popular research animal for over 100 years already. They are abundant, hardy, and easy to both collect and to care for (Lillie & Just, 1913). Those characters make them an excellent study organism, and therefore it is not surprising that they were among the first animals to be bred and raised entirely in captivity (Hatscheck, 1885; Wilson, 1892; Zeleny, 1906; Shearer, 1911). Using a technique very similar to the one described above from Grave's study, E.E. Just raised captive bred Platynereis larvae to maturity (Just, 1922). The worms were "spawned" by cutting along the length of the body to release the gametes (both eggs and sperm) prior to adding dilute sperm to fertilize the eggs. The fertilized eggs were transferred (following several washes with clean seawater) to freshly prepared dishes and the larvae were allowed to develop. Because the eggs are relatively well provisioned in this species, the larvae did not require feeding for several days, so the developing larvae were cultured in large cylindrical "balanced aquarium systems" in which diatoms were allowed to grow. It was soon possible to collect animals in the field, spawn them, and subsequently raise those juveniles through several generations in the laboratory (e.g., Grave, 1933).

It is always somewhat surprising to me that early researchers
had such success with breeding these animals when it seems
that even with the amazing array of advanced aquarium technology
available today, few people have significantly greater success with
raising the larvae of marine invertebrates.

It is always somewhat surprising to me that early researchers had such success with breeding these animals when it seems that even with the amazing array of advanced aquarium technology available today, few people have significantly greater success with raising the larvae of marine invertebrates.

As with the polychaetes, crustaceans were among the early success stories of larval biologists. Of course some people were successfully culturing the brine shrimp Artemia salina and the water flea Daphnia magnaby the turn of the century (e.g., Knörrich, 1901), but I doubt that these animals are of much interest to the average reef-keeper. However, other crustaceans, such as the American lobster Homarus americanus were also early successes in breeding experiments (Herrick, 1896; Mead, 1908). Although scientists could not yet induce the animals to spawn, they collected gravid (egg-bearing) females and carefully removed the brood before releasing the unharmed female. These eggs were placed into a tall cylindrical tank, with constant water flow into the bottom of the tank via a siphon tube (Figure 1). As the eggs hatched into swimming larvae, they would be washed from the cylindrical tank (A) into the culture tank (B), where a motor-driven propellor would keep both the larvae and their food in suspension. The larvae were prevented from escaping or being washed out of the tank by a fine mesh screen covering the overflow standpipe (C). The biggest obstacle to be overcome in the captive culture of lobsters was the voracious appetite of the larvae, and the strong cannibalistic tendencies. The larvae must be fed copious quantities of pelagic copepods and other crustacean larvae to prevent them from consuming one another during the pelagic period. Using large tanks which remain well-mixed also helps prevent cannibalism because the larvae simply do not encounter one another very frequently (Galtsoff, 1937). Once culture methods were described for lobsters, other crustaceans, such as Dungeoness Crab, were quickly discovered to have similar requirements and habits (e.g., MacKay, 1937).

Surprisingly, at least to me, chitons were also among the first successfully bred marine invertebrates (Kowalevski, 1883; Heath, 1899). For Chaetopleura apiculata, gametes were collected by placing 25-30 gravid individuals into constant strong flow for 24 hours, and then removing the animals and allowing them to stand undisturbed over night (Grave, 1932). Once the sperm and eggs were released, the eggs were collected by pipette and transferred to a new dish with clean water. This species produces larvae which are well-provisioned with yolk, and therefore require no additional feeding until they metamorphose 7 to 12 days post-fertilization. Other molluscs which proved early success stories included the oyster drill Urosalpinx cinerea (Brooks, 1879; Federighi, 1937), the American oyster Crassostrea virginica (Brooks, 1880; Prytherch, 1924; Wells, 1926; Galtsoff, 1930a, 1930b; Galstoff et al., 1930) and the Japanese oyster Ostrea gigas (Galtsoff & Smith, 1932). It is not surprising that commercially important species and their predators were among the earliest animals to be bred in captivity. Just as then, researchers today are often most strongly motivated to solve problems of immediate economic and public concern -- I will not go into further detail on these animals, but will use the oyster as our example here. In this case, 200-500 larvae were suspended in funnel-shaped glass jars with a small wooden airstone placed at the lowest point in the culture. The water was replaced daily with coarsely-filtered natural seawater (to remove larger competitors or predatory animals). Early researchers tried collecting the larvae by filtering the cultures through filter paper, bolting silk, and even high speed centrifuge, but greatest success came with the introduction of mesh sieves which allowed researchers to filter larvae from cultures without ever removing them from the water. Early sieves were metal, and had to be coated with celluloid to prevent toxicity effects (Prytherch, 1924; Wells, 1926), but modern sieves are made of nylon, and toxicity is no longer an issue to be overcome. The issue of how to get the mature larvae to settle remained a problem for many years. Prytherch (1934) discovered that larvae exposed to trace amounts of copper would settle, and many authors since have used this acute toxicity response of larvae to get them to settle and metamorphose into the adult body form. It was not until recently that the chemical stimulus for oyster settlement was isolated and identified (Zimmer-faust & Tamburri, 1994).

The other group of marine invertebrates that have proved to be a popular research animal, especially in terms of developmental biology, is the echinoderms (sea stars, sea cucumbers, urchins and their allies). Sea stars, such as Asterias & Solaster, and sea urchins, such as Arbacia and Strongylocentrotus, were early choices for studying developmental patterns of fertilized eggs and the fate of cell-lineages in an embryo (e.g., Delage, 1904; Gemmill, 1912-1915, 1914; Lillie, 1919; Morgan, 1927; Just, 1928; Goldfarb, 1929; Harvey, 1932; Fry, 1936). Early researchers were typically forced to sacrifice the animals in order to spawn them (the gonads were dissected out of the body), but several methods of chemical stimulation are now commonly used to induce spawning in the mature animals without killing them (see Strathmann, 1987). The fertilized eggs were raised in much the same manner as outlined in the other groups I have already described, but as techniques for algal culture became more sophisticated, researchers moved from "balanced system" cultures to feeding larvae pure strain algal cultures of unicellular algae such as Nitzschia, Dunaliella & Chlorella (e.g., Larsen, 1937). By switching to pure staring algal cultures, contamination was reduced, many more larvae could be cultured in a smaller culture volume, and identical conditions could be replicated each time larvae were maintained. These techniques are now standard for research use, but "balanced system" cultures may still work fine for the aquarist at home who wants to simply raise a few larvae of some animal that has unexpectedly bred in their reef tank.

Well, I must admit that I have been saving the best (or at least the group most interesting to the majority of reef-keepers) for last. The captive culture of cnidarians (sea anemones, corals and their allies) is probably an ultimate goal of most people who set up a reef tank at home. Although I doubt many people plan to culture jellyfish at home, the polyp stage of the jellyfish Aurelia was found to be a hardy and interesting research animal around the turn of the century. Several accounts were published of researchers successfully rearing the scyphistoma (fancy name for the poylp stage of any true jellyfish) on naturally collected plankton (e.g., Delap, 1905, 1907). However, these studies make no reference to the successful culture of the medusa (jellyfish) stage of these animals. I could, in fact, not find any old reference to the culture of jellyfishes, and it is only recently that even large public aquaria, such as Monterey Bay, have attempted long-term gelatinous zooplankton displays. There has been significant interest in the predatory effects of jellyfishes on both zooplankton and larval fishes for a long time, so I assume that these animals have been successfully cultured; I simply cannot find any old references to the techniques.

The first anemone for which I have found reports of propagation is Sagartia luciae (Davis, 1919). These anemones did not reproduce sexually in the lab, but were observed to undergo asexual fission (splitting of the column) when placed in deep dishes with lots of diffuse sunlight and occasional feedings of fish, crab or beef. Although some reef keepers occasionally report fission of anemones in their reef tanks, the recent survey of captive survival rates of tropical anemones spear-headed by Joyce Wilkerson suggests that less than half of the anemones purchased survive for extended periods of time, and of those that manage to survive, less than 1 in 20 ever reproduce. Based on similar findings, combined with observations of widespread decline of anemone popularions in the Pacific, I hear through the grapevine that Daphne Fautin (California Academy of Sciences & University of Kansas -- Coauthor of Field guide to Anemone Fishes and their host Sea Anemones has been active in trying to stop importation of these animals. I will not get on my soapbox long here, but if you are unsure that you can provide all conditions captive animals require to complete their ENTIRE natural lifespan in captivity, PLEASE do not buy one. Although we may have the best of intentions, by purchasing animals that will not survive, we are encouraging suppliers to import more and (perhaps inadvertantly) damaging the very habitats we so admire. If at all possible, I strongly encourage people to buy captive raised animals, and I applaud the efforts of organizations such as G.A.R.F. for trying to develop propagation facilities for some of the popular cnidarians offered for sale in the reef aquarium trade. OK, enough of my digression, I'll get back to the topic of the article.

Thomas Wayland Vaughan was the first person
for whom I could locate accounts of rearing corals
from planula larvae
(he used these techniques during his 1908-1915
study which was published in 1916).

Thomas Wayland Vaughan was the first person for whom I could locate accounts of rearing corals from planula larvae (he used these techniques during his 1908-1915 study which was published in 1916). During Vaughan's study of the corals of the Tortugas, he succeeded in spawning and raising larvae from 5 species of coral (Astrangia solitaria, Favia fragum, Agaricia purpurea, Porites clavaria, and Porites asteroides (Vaughan 1910, 1911, 1919). He managed to keep several colonies of Favia fragum and Porites asteroides alive from larvae through settlement and five years of subsequent growth (some reached nearly 10 cm in diameter during that time), which was a remarkable accomplishment for the time. OK, maybe you don't think that keeping a coral colony alive for 5 years is such a remarkable accomplishment. Let me put it this way: even with the bewildering array of gadgets and techniques available to reef-keepers today, I would hazard to guess many people could not boast of five years of growth among their corals, and how many of us can boast of having bred and raised any coral in captivity. Now imagine that I took away your protein skimmer, lights, power heads, aerators, and so on. Vaughn had none of the equipment we have come to consider "necessary" for successful culture of corals, and yet had more success with the animals than most of us have today. He was forced to set up a siphon system in which "stale water" was drawn off the top of his tanks and "fresh seawater" was replaced via gravity feed (from tanks suspended above the culture aquaria) because he had no effective means of filtration. He also lacked any high output lights, let alone ones with proper spectra; he was forced to rely on diffuse sunlight from a nearby window for his tanks. I think that the culture of coral larvae through settlement and five years of growth suddenly becomes an accomplishment that we must all acknowledge when put in this perspective.

Well, I hope that I have succeeded in passing along some of the history of captive breeding in marine invertebrates. I think that it is not only interesting to learn how early researchers succeeded in raising some of these animals, but I also feel it is only fair to remember and give credit to those people who started our hobby along the path that so many of us now enjoy. I hope that you have enjoyed reading this article, and I wish you luck in your own efforts to breed some of these fascinating animals at home.


Literature Cited:

Allen, E.J. 1914. On the culture of the plankton diatom Thalassiosira gravida, Cleve, in artificial seawater. J. Mar. Biol. Assoc. 10:417.

Allen, E.J. & E.W. Nelson. 1910. On the artificial culture of marine plankton organisms. J. Mar. Biol. Assoc. 8:421.

Brooks, W.K. 1879. Preliminary observations upon the development of the marine prosobranchiate gastropods. Stud. Johns Hopkins University Biol. Lab., 1877-78. 16 pp.

Brooks, W.K. 1880. Development of the American Oyster. Stud. Johns Hopkins University Biol. Lab., 4:1.

Davis, D.W. 1919. Asexual multiplication and regeneration in Sagartia luciae Verrill. J. Exper. Zool. 28:161.

Delage, I. 1904. Élevage des larves parténogénétiques d'Asterias glacialis. Arch. De Zool. Expérimentale 4, Vol. 2

Delap. 1905. Report of Sea and Inland Fisheries of Ireland for 1902 and 1903.

Delap. 1907. Report of Sea and Inland Fisheries of Ireland for 1904 and 1905.

Federighi, H. 1937. Culture methods for Urosalpinx cinerea. In: Culture Methods for Invertebrate Animals, F.E. Lutz, P.S. Welch, P.S. Galtsoff & J.G. Needham (eds.). 532.

Fry, H.J. 1936. Studies of the mitotic figure. V. The time schedule of mitotic changes in developing Arbacia eggs. Biol. Bull. 70:89.

Galtsoff, P.S. 1930a. The role of chemical stimulation in the spawning reactions of Ostrea virginica and Ostrea gigas. Proc. Nat. Acad. Sci. 16:555.

Galtsoff, P.S. 1930b. The fecundity of the oyster. Science 72:97.

Galtsoff, P.S. 1937. Hatching and rearing larvae of the American lobster, Homarus americanus. In: Culture Methods for Invertebrate Animals, F.E. Lutz, P.S. Welch, P.S. Galtsoff & J.G. Needham (eds.). 233.

Galtsoff, P.S., H.F. Prytherch & H.C. McMillin. 1930. An experimental study in production and collection of seed oysters. U.S. Bur. Fish. Doc.1088, Bull. 46:197.

Galtsoff, P.S. & R.O. Smith. 1932. Stimulation of spawning and cross-fertilization between American and Japanese oysters. Science 76:371.

Gemmill, J.F. 1912-1915. The development of the starfish Solaster endeca. Trans. Zool. Soc. London 20.

Gemmill, J.F. 1914. The development and certain points in the adult structure of the starfish Asterias rubens. Philos. Trans. Royal Soc. London B, Vol. 205.

Goldfarb, A.J. 1928. Changes in the agglutination of aging germ cells. Biol. Bull. 57:350.

Gran, H.H. 1931. On the conditions for the production of plankton in the sea. Cons. Perm. Internat. pour l'Exploration de la Mer. Rapp. Et Procès-Verbaux des Reunions. 7:37.

Gran, H.H. 1932. Phytoplankton methods and problems. J. du Cons. Internat. pour l'Exploration de la Mer. 7:343.

Gran, H.H. 1933. Studies on the biology and chemistry of the Gulf of Maine. Biol. Bull. 64:159.

Grave, C. 1902. A method of rearing marine larvae. Science 15:579.

Grave, B.H. 1932. Embryology and life history of Chaetopleura apiculata. J. Morph. 54:153.

Grave, B.H. 1933. Rate of growth, age at sexual maturity and duration of life of certain sessile organisms at Woods Hole, Massachusetts. Biol. Bull. 65:380.

Harvey, E.N. 1932. Physical and chemical constants of the egg of the sea urchin, Arbacia punculata. Biol. Bull. 62:141.

Hatscheck, B. 1885. Entwicklung der Trochopohora von Eupomatus uncinatus (Serpula uncinata). Arch. Zool. Inst. Wien. 6

Heath, H. 1899. The development of Ischnochiton. Zool. Jhrb. 12:567.

Herrick, F.H. 1896. The American lobster, a study of its habits and development. Bull. U.S. Bur. Fish. 15:1.

Just, E.E. 1922. On rearing sexually mature Platynereis megalops from eggs. Amer. Nat. 56:471.

Just, E.E. 1928. Methods for experimental embryology with special reference to marine invertebrates. The Collecting Net, Woods Hole, Mass. 3

Knörrich, F.W. 1901. Studien ueber die Ernaehrungsbedingungen einiger fuer die Fischproduction wichtiger Microorganismen des Süsswassers. Forsch. Ber. Biol. Stat. Blön. 8:1

Kowalevski, A. 1883. Embryogenic du Chiton polii. Ann. Mus. Hist. Nat. Marseilles. 5

Larsen, E.J. 1937. The laboratory culture of the larvae of Asterias forbesi. In: Culture Methods for Invertebrate Animals, F.E. Lutz, P.S. Welch, P.S. Galtsoff & J.G. Needham (eds.). 550.

Lillie, F.R. The problems of fertilization. University of Chicago Press, Chicago, IL.

Lillie, F.R. & E.E. Just. 1913. Breeding habits of Nereis limbata at Woods Hole, Mass. Biol. Bull. 24:147.

MacKay, D.C.G. 1937. Notes on rearing the pacific edible crab, Cancer magister. In: Culture Methods for Invertebrate Animals, F.E. Lutz, P.S. Welch, P.S. Galtsoff & J.G. Needham (eds.). 239.

Mead, A.D. 1908. A method of lobster culture. Bull. U.S. Bur. Fish. 28:221.

Miquel, P. 1890-1893. De la culture artificielle des diatomeès. Le Diatomiste 1:73; 93:121; 149:165.

Morgan, T.H. 1927. Experimental embryology. Columbia University Press. Chpt 27.

Prytherch, H.F. 1924. Experiments in the artificial propagation of oysters. U.S. Bur. Fish. Doc. 961:4.

Prytherch, H.F. 1934. The role of copper in the settling, metamorphosis and distribution of the American oyster Ostrea [sic] virginica. Ecol. Monogr. 4:47.

Schrieber, E. 1927. Die reinkultur von marinem phytoplankton und deren bedeutung fü die erforschung der prouktions fähigkeit des meereswassers. Wiss. Meeresuntersuchungen Abt. Helgoland, 16. 10:1.

Shearer, C. 1911. On the development and structure of the trochophore of Hydroides uncinatus. Quart. J. Micro. Sci. 56:543.

Strathmann, M.E. 1987. Reproduction and Development of Marine Invertebrates of the Northern Pacific Coast: Data and methods for the study of eggs, embryos, and larvae. University of Washington Press, Seattle, WA. 670pp.

Vaughan, T.W. 1910. The recent Madreporaria of southern Florida. Carnegie Inst. Of Wash., Year Book. 9:135.

Vaughan, T.W. 1911. The Madreporaria and marine bottom deposits of southern Florida. Carnegie Inst. Of Wash., Year Book. 10:147.

Vaughan, T.W. 1919. Corals and the formation of coral reefs. Smithsonian Inst. Publ. 2506, Report of 1917. p.189.

Waksman, S.S. & K.R.N. Iyer. 1932. Synthesis of a humus-nucleus, an important constituent in soils, peats and composts. J. Wash. Acad. Sci. 22: 41.

Wilson, E.B. 1892. Cell lineage of Nereis. J. Morph. 6:361.

Wilson, H.V. 1894. Observations on the egg and gemmule development of marine sponges. J. Morph. 9:277.

Wilson, H.V. 1907. On some phenomena of coalescence and regeneration in sponges. J. Exper. Zool. 5:245.

Wells, W.F. 1926. A new chapter in shellfish culture. Report, Conserv. Comm., N.Y., 1925. 1926:93.

Zeleny, C. 1906. The rearing of serpulid larvae. Biol. Bull. 8:308.

Zimmer-faust, R.K. & M.N. Tamburri. 1994. Chemical identity and ecological implications of a waterborne, larval settlement cue. Limnol. Oceanogr. 39:1075.

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More on Gorgonians

In the February 1997 newsletter I wrote about a simple way to propagate gorgonians. After discussing this with several other people and after making another batch of cuttings of a purplish-brown thick-skinned photo synthetic gorgonian, I'd like to add some updated information.

But first, just in case you missed last month's article, I'll briefly go over the simple procedure. Cut off a branch of gorgonian. Strip 1" - 3/4" of skin off the central stem on one end. Blot the stem dry with a paper towel. Using Super Reef Gel (super glue gel), glue that end onto the side of a rock. Don't get glue on the gorgonian's skin which could irritate it and even cause it to rot. When gluing the stem to the rock, make sure the skin above the stem touches the rock at least a little bit. After the stem is tacked to the rock, embed the stem in a little extra super glue. This really bonds it to the rock. Do this all out of water of course.

Next, return the cutting to your tank. The gorgonian skin will now grow down over the rock and down over the whole glue-embedded stem within a couple of weeks!

Last month I mentioned that I (as well as others) have had problems trying to get gorgonians to attach when we tried sticking plastic or wooden toothpicks up into the stem of a cutting of gorgonian. Next we tried gluing the plastic or wood onto a rock and also just lodging toothpicks with attached gorgonians into holes in the rock. This didn't work very well. The gorgonians rotted off the toothpicks from irritation apparently.

I had a chance to try it again but in a slightly different way last month! I made 10 small cuttings, some as short as one inch, which is usually too short. I accidently broke the stem off of five of them while using wire strippers to remove the skin. You can avoid this by just removing 1/8" lengths of the skin at a time until you have removed a half inch. Out of 10 cuttings, I lost two of them which isn't bad, but still not quite ideal. By using successful techniques we can improve our survival rate to more than 90%. We can often succeed with 10 out of 10 cuttings. I still think it's unlikely to get 100 out of 100 to survive.

I feel the reason I lost two out of 10 is as follows: One cutting was the shortest one and although I didn't break off the stem, the skin fell off a couple of days later anyway. The probable cause was that the cutting was too short and the remaining 3/8" of attached gorgonian skin was probably loosened from the stem by rough handling when pulling on it to strip the stem. The solution would be to not cut them this short and to handle them more gently. Make your cuttings at least 2 inches long so that you have at least 1" of undisturbed skin still attached above the bare stem glued to the rock.

So, here's what I did with the five really short cuttings that ended up with no stem protruding from them. They were already too short to strip any more skin from their stems. I could have thrown them away or I could have tried another method of attachment. I thought about sticking plastic toothpicks in them but this method hadn't worked for me in the past.
A broom happened to be right next to me at the kitchen counter. I wondered if a natural broom straw would be skinny enough to be a bit less irritating to the gorgonian than a toothpick would be. What the heck: I grabbed the broom and plucked a skinny straw and cut it up into inch long pieces then put them in salt water for only a couple of minutes (Maybe this helped, maybe it didn't). I pushed the pieces of broom straw up into the short gorgonian cuttings alongside their stems. I then super glued the broom straws onto the aragonite rocks the same as I did with the five cuttings that still had their own stems protruding beneath them. One of the cuttings on a broom straw fell off a couple of days after gluing it to a rock - no doubt from straw irritation.
The remaining eight cuttings (four of each style) all attached nicely, but there were a couple of differences between the two styles. The gorgonians on the broom straws grew down onto the rock and down over only part of the straw before the skin veered off to the side and grew a little more over just the rock. The cuttings that were glued with their own stems did attach more quickly and the polyps opened more fully from the start.

In summary, thick-skinned photo synthetic gorgonians seem to be more sensitive to irritation than the skinny more solid types which can sometimes be wedged into a hole drilled in a rock. Crunchy Styrofoam ball chunks (used for crafts - discussed last month) are used to stuff into the hole to hold the gorgonian in place. This method has not worked well for ME with the thick- skinned varieties.
Some varieties of gorgonian do not have a well-defined brown central stem, but a more calcareous looking (and feeling) stalk that can be carved with a knife. Just carve up to the most solid part on all sides with a knife. Stop where it feels mostly solid. Then glue this stalk to a rock as you would glue a regular brown stemmed gorgonian. And remember: "Hair algae today, gorgonian tomorrow."

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