Nutrition
 
 

cartoon drawing of Aristotle sitting on a sea urchinPossible "Aristotlelian" explanations for the sea-urchin lantern data.

He would conclude that more fishing by more people would reduce the number of sea urchin-eating fishes, leading to more sea urchins and thus to greater grazing pressure on the algae. With less algae the lanterns increase in size. YES, and we know that less algae will lead to larger relative lantern sizes.

He would deduce that more humans would lead to increased nutrient enrichment in the form of agricultural run-off and sewage, and to more algae and more sea urchins. NO, however true the first part, he would know that this would NOT lead to larger relative lantern sizes, but just the opposite. More algae would lead to smaller relative lantern size unless, of course, numbers of sea urchins were to keep pace with the increased algal abundance.

He would conclude that a greater population of humans would consume more sea urchins. Well, however reasonable a conclusion, especially since Greek gourmands are thought to have invented "sea urchin on the half shell", he would know that it isn't correct. First, he would know that the long-spined (and relatively scrawny) Diadema antillarum is not eaten by Caribbean peoples; rather, it is the shorter-spined Tripneustes ventricosus or "sea egg" that is eaten. Second, he would know in any case that consumption of more urchins of any species would lead to increased amounts of algae and thus to smaller relative lantern size, not larger.

He would conclude that more fishing by more people would reduce the number of herbivorous fishes, leading to more food for sea urchins and thus to more sea urchins, and ultimately to greater grazing pressure on the algae. Well, the first part is correct in that a greater human population would lead to more fishes being caught. However, with his marine "smarts" he would recognise that, given a choice, people would prefer to eat the flesh of carnivorous fishes (including triggerfishes and perhaps hogfishes, both of which eat sea urchins) over herbivorous fishes (such as algal-eating parrotfishes), which brings us back to the first point in this quiz.

He would say the heck with it and simply swallow his hemlock poison. NO, that was what Socrates did when confronted with the same question.

 
 
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