Patrick Krug, a nudibranch professional on the California State College, Los Angeles who was not concerned within the examine, stated this “steal your meal, and eat you, too” technique doubtlessly rewrites how ecologists perceive meals chains. “You normally consider a predator consuming a prey merchandise, not consuming what the prey merchandise is consuming,” he stated.
To check whether or not Cratena nudibranchs had a penchant for hydroids that had freshly eaten, the authors did lab experiments on 25 slugs, presenting every with 4 mesh luggage. These luggage held nothing, empty hydroids, hydroids that had simply been fed brine shrimp or brine shrimp solely.
In 14 of 25 circumstances, the nudibranchs “went straight to the baggage that contained fed hydroids,” stated Trevor Willis, a marine ecologist on the College of Portsmouth in Britain and lead writer of the examine. The slugs additionally ate about double the variety of fed polyps in comparison with unfed ones.
Subsequent, the researchers analyzed the weight loss plan of untamed nudibranchs by measuring an isotope referred to as nitrogen-15. When an animal eats one other organism, this heavier type of nitrogen turns into extra concentrated in its tissues than it was in its prey’s tissues, so the upper up the meals chain you go, the extra nitrogen-15 it’s best to discover.
Dr. Willis and his colleagues discovered that nitrogen-15 ranges of their nudibranchs had been decrease than they might anticipate if the animals had been consuming hydroids solely. This means that the slugs may be getting a major quantity of diet immediately from small plankton, which comprise decrease portions of nitrogen-15 than hydroids. Utilizing statistical fashions, the researchers estimated that these plankton presumably contribute as a lot, or extra, to those slugs’ diets because the hydroids themselves.
As for why sea slugs favor hydroids who’ve had their fill, Dr. Willis speculates that it’s a method for the animals to get energy from plankton whereas additionally not overeating hydroids, which they rely upon for shelter along with nourishment. “It appears counterintuitive that an animal would destroy its personal habitat,” he stated.
However that is purely conjecture for now, Dr. Willis stated, including that the analysis is a “first step” that raises extra questions than it solutions. Certainly one of these is whether or not different animals, like nudibranchs that eat coral, carry out kleptopredation. He added that unraveling these detailed feeding interactions will assist scientists perceive how power flows by ecosystems, and the way such dynamics would possibly shift with local weather change.
“As soon as we now have an thought of what’s happening on the species stage, we will put these little tales collectively and have a look at entire communities,” he stated.
Proceed studying the principle story