Turning the Tables

Most of the time, life in the oceans works in one direction: the big guys eat the little guys. That passes nutrients up the food web. But sometimes, the little guys may turn the tables. Egged on by annual spawnings, they may poach the eggs of larger species. That passes nutrients down the food web. Of course, the big guys then gobble up some of the egg eaters, scrambling things up.

Eggs are rich in essential fatty acids — compounds that are needed for normal development and body function. Eggs can supply a lot of the fatty acids in the animals that eat them.

Researchers at the University of Texas Marine Science Institute suspected that smaller organisms were feeding on the eggs of larger species. They tested that idea in 2020 and ’21, around the annual spawning of red drum, a game fish on the Texas coast. A single female releases millions of eggs, so the coastal waters around Port Aransas are filled with them in the fall.

The scientists collected several types of animals before, during, and after the fall spawning. They then tested the tissues of those organisms in the lab. The fatty acids in red-drum eggs have a unique chemical “fingerprint,” so the tests revealed which subjects had eaten the eggs. During and after the spawning season, high levels of those markers were seen in jellyfish and jellyfish-like organisms, as well as one small species of fish.

The study confirmed that these organisms can scramble things up—turning the tables on the big guys.

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