Learning from Oysters and Ox-goads

Learning (about Opportunities) from Oysters and Ox-goads

Dr. James J. S. Johnson

After him was Shamgar the son of Anath, who killed 600 men of the Philistines with an ox-goad; and he also delivered Israel. (Judges 3:31)

Oysters and oxgoads (also spelled “ox-goads”) are not usually mentioned in the same sentence, but they both can teach us something about being good stewards of our opportunities, especially opportunities that exist in less-than-ideal circumstances.


Under ideal circumstances we all can do a lot of good, but when circumstances handicap or restrict our potential—in ways we cannot circumvent—we just do the best that we can. That’s not just true for humans; that principle is displayed in the water-filtering services of those humble bivalves we call oysters—according to recent research involving the University of Maryland.(1),(2)

Specifically, Dr. Matthew Gray, an ecologist at the University of Maryland Center for Environmental Science, has recently provided a study showing how real-world conditions can handicap the ability of oysters to improve water quality (by filtering it, like a water purifier), compared to the water quality improvement provided by oysters observed in idealized experimental conditions.(1),(2)

Oysters feed on algae and other organic particles by pumping water through their gills. [Dr.] Gray said research he and others have done shows that an oyster’s filtration rate depends on a lot of environmental factors.(1)

Living in and below the tidal zone, in coastal shores, oysters must the flexible to survive.

Oysters commonly reside in the shallow intertidal and subtidal zones where they are exposed to a wide range of environmental conditions …  Although well adapted to the dynamic environmental conditions found in estuaries, oyster feeding rates and particle sorting efficiencies are sensitive to a variety of biological factors such as live algae composition and concentration … suspended organics and detritus …  [as well as] environmental factors such as salinity, oxygen, pH, and nutrient concentrations ….(2)

In other words, as they eat (by filter-feeding), oysters filter the waters that they live in. If those waters contain ideal conditions—such as temperature, salinity, dissolved oxygen levels, etc.—the oysters can filter lots of water, every day.

However, if oysters live in less-than-ideal conditions, they filter less water, and so add less “quality-of-life” improvement to their habitat.(1) This is shown by quantitatively comparing experimental results, from laboratory tests, to observational data of what oysters do in the wild.

This writer has previously reported on bivalve-produced benefits of water quality improvement—removing picoplanktonic algae biomass from coastal waters of the Chesapeake Bay—to prevent “dead zones”.

Another example [of providential ecology showing God’s glory] is found in Chesapeake Bay, which is burdened with excess nitrogen and organic nutrients that people release into its tributaries. The nitrogen compounds fuel picoplankton, which comprise ~15% of bay phytoplankton biomass during the summer. If left unchecked, their growth would lead to algal blooms that would block sunlight from submergent aquatic plants, leading to oxygen-depleted “dead zones”.(3)

The habitat heroes, who provide clean-up services to estuarial coast-waters, are oysters and mussels.

Thankfully, oyster reefs, bolstered by attached mussels, filter huge volumes of the bay’s water and consume the otherwise unrestrained picoplankton. This filtering ultimately benefits the dissolved oxygen and accessible underwater sunlight needs of the interactive Chesapeake Bay ecosystem.(3)

Laboratory experiments can facilitate interesting investigations, and may even yield informative data, but how much of those artificial scenarios are representative of real-world activities? With shellfish like oysters and mussels, as with other animals, field studies allow for observed-in-the-wild data that is much more relevant (and realistic) for understanding how such creatures really live.(4)

But even heroes need a little help from friends—or from environmental conditions. That’s why oysters—if they are living in not-so-optimal conditions—don’t “clean up” estuarial waters as efficiently as they could, if their workplace conditions were qualitatively improved.

Oysters are filter feeders that can help clean up the Chesapeake Bay, right? Many have seen the various web videos showing a dozen or so bivalves clearing a murky fish tank in just an hour. But are they such ecological superheroes that each one can siphon 50 gallons of water in a day? … 50 gallons of water in a day … “is about the near maximum rate at which the Eastern oyster will filter under laboratory conditions at optimum temperatures and very high-quality diets,” said Gray, whose specialty is the study of oysters, clams and mussels.(1)

But, what about bivalves feeding in normal (i.e., natural) conditions?  What about oysters that live in real bay-water? The water temperature makes a difference on how actively oysters filter-feed.

In reality, Gray said, under average conditions in the wild, …  “They don’t feed much at very low temperatures and get stressed out at super high temperatures,” he explained. They tend to be hungriest when the water is in a 10-degree range from the high 60s to high 70s Fahrenheit. Consequently, he pointed out, Bay oysters don’t eat or filter water year-round — not when a frigid winter sets in or when summer turns blistering.(1)

Also, what about the water’s saltiness? If the oyster-bed is subjected to a drop in salinity the oysters lose their appetite for filter-feeding.(1) Likewise, what about water turbidity, i.e., clarity versus cloudiness?

Turbidity also can make a difference. While oysters can clear up cloudy water, Gray said that “if there’s a lot of sediment and dirt in the water column, they’ll spend more time sorting that than just ingesting it. And if it’s really, really bad they’ll just stop feeding. They’ll close up.”(1)

Also, the amount and type of available food makes a difference. Some algae are delicious and nutritious, yet other algae are undesirable or even harmful. Even oysters have taste sensitivities!

Furthermore, a relaxed oyster will filter-feed more than a frightened oyster. So, if predatory crabs are lurking nearby, oysters will defend themselves as bivalves do, by “clamming up” (i.e., closing their shells together), which necessarily interrupts an opportunity to filter-feed.(1) Better to eat less plankton than to be eaten by a carnivorous crustacean!

Meanwhile, there is a lesson for us humans: notice that oysters nevertheless filter-feed at a less-than-optimal level—which is better than nothing!  So they do contribute some improvement to water quality in their estuarial waters, even when doing so in less-than-ideal habitat conditions.(1),(3)

Of course, ideal circumstances usually exist only in imaginations. Yet the lack of ideal circumstances is never an excuse to avoid doing what is feasible with whatever is available.

Consider the example of the Old Testament champion named Shamgar, whose example is a true lesson about doing—with God’s grace—whatever we can, with whatever we have.

After him was Shamgar the son of Anath, who killed 600 men of the Philistines with an ox-goad; and he also delivered Israel.(5)


But what was an ox-goad? And why did Shamgar use an ox-goad as a weapon against Israel’s enemies? An ox-goad (Hebrew: malmad) was a farm tool, basically a pointed cattle-prod, for physically motivating oxen to move along, similar to how spurs are used to “instruct” (i.e., motivate) horses to speed up.(6)

The Hebrew noun translated as “ox-goad” (malmad) is derived from the Hebrew root verb lamad, literally meaning “to learn” (or, if used to indicate “causing-to-learn”, it is often translated as “to teach”). So Shamgar literally taught the Philistines a “lesson” with his ox-goad!(6)

But why not use a sword, spear, of bow-propelled arrows?  Perhaps Shamgar was deprived of his cultural equivalent of “2nd Amendment rights” (i.e., the right to own and bear arms)—because other Scriptures indicate that Philistines were known to confiscate weapons when they occupied Israel.(7)

If that was the situation in Israel (during Shamgar’s generation), Shamgar never had “ideal” weapons for battling Philistines. However, shunning excuses about what he did not have, Shamgar made good use of what he did have (i.e., an ox-goad), under less-than-ideal circumstances.

And God blessed Shamgar’s resourcefulness and courage—by giving Shamgar (and his people) a providential deliverance.(5)

May God give us wisdom and courage, to use whatever resources we now have, for that which is truly good.



  1. Wheeler, Timothy B. 2020. Pumped-up performance: Oysters’ filtering feat overstated. Fisheries News. Posted (May 20, 2020) on BayJournal.com at https://www.bayjournal.com/news/fisheries/pumped-up-performance-oysters-filtering-feat-overstated/article_bbe67d38-8f09-11ea-a5ab-5fd7465dee21.html .
  2. Quoting from Wang, L., J. Song, et al. 2020. Adaptive Feeding in the American Oyster Crassostrea virginica: Complex Impacts of Pulsatile Flow during Pseudofecal Ejection Events. Limnology and Oceanography. Posted at https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.1002/lno.11433 . See also Gray, M. W., P. zu Ermgassen, et al. Spatially Explicit Estimates of In Situ Filtration by Native Oysters to Augment Ecosystem Services during Restoration. Estuaries and Coasts. 42:792–805.
  3. Quoting Johnson, James J. S. 2019. Termite Skyscrapers Hidden in Plain View. Acts & Facts. 48(4):21, posted at https://www.icr.org/article/termite-skyscrapers-hidden-plain-view . See also Gedan, K. B., L. Kellogg, and D. L. Breitburg, 2014. Accounting for Multiple Foundation Species in Oyster Reef Restoration Benefits. Restoration Ecology. 22 (4): 517-524;  Pipkin, W. 2018. Freshwater Bivalves Flexing their Muscles as Water Filterers. Chesapeake Bay Journal. 28(7):1.
  4. Johnson, James J. S. 2015. Crayfish, Caribou, and Scientific Evidence in the Wild. Acts & Facts. 44(6):20, posted at https://www.icr.org/article/crayfish-caribou-scientific-evidence .
  5. Judges 3:31.
  6. Young, R. 1984. Young’s Analytical Concordance to the Bible.Peabody, MA: Hendrickson Publishing (reprint of 1879 edition), at pages 410 (malmad = ox-goad), 595 (lamad = to learn), 962 (piêl and pual forms of lamad = to teach. to be taught).
  7. 1st Samuel 13:19-22.



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