Many may think of FHL as the stomping ground of biologists of many stripes, with an occasional physical or chemical oceanographer or biologically-oriented engineer thrown in. But we also have a long tradition of hosting paleontologists, especially those interested in brachiopods, who come here to study modern counterparts of their fossil study organisms. This spring we received some lovely reminiscences from one such scientist who treasured his time at FHL back in 1974, and these stories turned into a Tide Bite! I hope you enjoy this as much as I did.
Recollections of a Summer Student from FHL’s Program in the 1970s
by Markes E. Johnson, Professor Emeritus, Williams College
Markes Johnson is the Charles L. MacMillan Professor of Natural Science, Emeritus, at Williams College in Williamstown, Massachusetts, where he taught courses in historical geology, paleontology, and stratigraphy in the Geosciences Department over a 35-year career. He is the author of Islands in Deep Time – Ancient Landscapes Lost and Found (2023, Columbia University Press, 312 p). This essay is a shortened version of a piece on San Juan Island from a collection of stories in a new manuscript under the working title Treasure Islands: Unexpected Riches in Natural History from Far Isles. With a fascination for islands stimulated during his formative student years beginning at FHL, Prof. Johnson describes experiences in ecology and paleoecology from eighteen places scattered around the world including settings such as the Galápagos Islands, Seychelles Islands, and Lizard Island: like the FHL, a research station located on the Great Barrier Reef off the coast of Queensland, Australia.
Among those who patronize lab courses at Friday Harbor Labs are student paleontologists, who consider it a necessity to learn about the biology of living invertebrates related to fossilized forebears. I completed a summer course at FHL fifty years ago in 1974, having finished my first year of graduate studies at the University of Chicago. Sustained by upwelling nutrients in the mighty ocean current that descends from Alaska to the Salish Sea, the raw materials for the study of marine invertebrates at the UW Labs on San Juan Island draw from a diverse fauna of roughly 4,000 marine invertebrate species. FHL’s principal instructor was Professor Eugene Kozloff and he proudly told us he had subjected virtually all of the local fauna across multiple phyla to a taste test.
Fossil shells and the exoskeletons of many other diverse invertebrates are found and disinterred from burial without any trace of soft parts. Instruction at the Labs remedied this state of affairs for the novice paleontologist. Brachiopods are among the most abundant invertebrates in Paleozoic rock formations deposited between 540 to 250 million years ago. They are not common in today’s seas and my classmates may not have been as excited as I was to study them in the flesh. For a budding paleontologist, our class excursion to Mitchell Bay on the west side of San Juan Island was like a dream come true. Terebratalia transversa brachiopods could be collected during low tide by searching for them in cavities beneath slabs of rock in the tide pools. Individual shells had to be cut from the stalk that secured them to the rocks. We had permission to collect just enough for the dissection exercise that day. Fossils with a similar shape from long-past seas have a pallor consistent with the limestone in which they are buried, but these pulsated with a pink coloration that effused the animals’ inner mantle and the rest of the shell.
It came as a surprise upon dissecting a brachiopod that its inner organs were so insubstantial. The feeding device, or lophophore, is a feather-like appendage attached to a pair of skeletal loops within the shell. Unlike an ordinary clam, there are scarcely any muscles. A potential predator would surely dismiss the brachiopod as unworthy of the effort required to open the shell, versus the caloric benefit of consuming the scant fleshy parts. Professor Kozloff failed to tell us what a brachiopod tasted like, but precious little was available on which to base a credible judgement. At the end of the day, I begged my classmates to let me keep our harvest of shells. I also scoured the FHL’s library for details on the species and its distribution (Bernard 1972). Older literature from the early 1900s revealed much about the species’ variation in shell shape. This came as a shock to the novice paleontologist, on account of the proclivity to assign a new species name to anything that looks remotely different from everything else.
Most of the marine species in a place like the Salish Sea are not prone to fossilization, because they lack the hard parts necessary for preservation. Another outcome of our course work was to demonstrate the enormous diversity of marine life unlikely to achieve fossilization except under extraordinary conditions. A day trip aboard the Labs’ research vessel, at that time the R/V Hydah, gave us the experience of a dredging operation that yielded a good many subjects for further study. One such animal was a Basket Star, also known as the Gorgon’s Head (Gorgonocephalus eucnemis). It was collected at a depth of some 20 meters. The animal is related to sea stars and urchins, but unlike sea urchins the Basket Star exhibits a set of five trunk arms that radiate from the center through a nest of multiple bifurcating appendages to terminate in the most delicate distal tip-ends (Figure. 1). Its common name recalls monsters in Greek mythology, one of whom was the Medusa with her deadly gaze of writhing snakes for hair. This marine gorgon relies on a sense of smell to track potential prey (zooplankton) small enough to be ingested through the mouth at its center. The delicate arms of the Basket Star are unlikely to achieve fossilization except as broken fragments.
The most mind-expanding experience for me that summer in 1974 occurred when our class was summoned in the middle of the night to witness the spectacle of a mass-spawning event by a species of marine worm (Alitta branti), a polychaete belonging to the phylum Annelida. Professor Kozloff and his assistants woke us up after midnight and ushered us onto the station pier (Figure 2). Floodlights cast beams into the water below, which teemed with thousands of individual marine worms. The great mass was engaged in a writhing dance of life, simultaneously shedding their male and female gametes into the water. These were large annelids, individually 25 to 35 cm in length. The water was turbid with their spawn, turning it into a milky color. Untold numbers of egg and sperm had the opportunity to unite in fertilization, leading to a whole new generation. Most of the fertilized byproduct would be consumed by fish and other eager predators, but enough would survive to insure the species’ future in the Salish Sea.
The soft body of an annelid may appear to have no hard parts, but they have jaws composed of a tough organic substance suitable for fossilization. Known as scholecodonts, these are profusely preserved in strata spanning the entire Phanerozoic from as much as 500 million years ago. I dissolved the head from one of the night’s performers in peroxide to extract a pair of jaws that looked very much like small garden shears. The night’s stand-out lesson was not about the potential for fossilization, but rather the overwhelming statistics that only a small fraction of fertilized eggs would survive to reach adulthood and repeat a future spawning event. So it goes with the vast number of marine invertebrates, with the exception of a few known to brood their eggs. If not the case, any one species with such a prodigious output of gametes would rapidly fill the seas solid with their progeny, in violation of the balance of nature.
At the conclusion of the 1974 summer session at Friday Harbor, I returned to the rock formations and their fossils that would become the topic of my dissertation research on the vast seas spread across the ancestral North American continent more than 430 million years ago. I did so having gained insights about the bounty and balance of marine life, which stayed with me as crisp lessons for the rest of my career. To this day, I am fascinated by dense brachiopod populations preserved as a byproduct of a successful spatfall recorded in the fossil record (Johnson and Gudveig Baarli, 2023).
References
Bernard F.R. 1972. The living brachiopoda of British Columbia. Syesis: 5, 73–82.
Johnson M.E. and B. Gudveig Baarli. 2023. Spat fall and mature growth of large-shell brachiopods (Stricklandia lens lens) from the Solvik Formation (lower Silurian) at Sandvika in the Oslo Region of southern Norway. Norwegian Journal of Geology: 103(202305).
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