Like humans, spiders too watch their diets

Washington, May 28 (ANI): Just like humans, spiders too make sure that they get a balanced diet, according to a new study.

The research has shown that many meat-eating insects and animals selectively feed on certain body parts to balance their nutritional intake.

And these choices are probably driven by hunger pangs.

For ant-eating Zodarion spiders, the focus of the study, such pangs might compel them to eat an ant head, leg or gut, reports Discovery News.

Stano Pekar, lead author of the study, said that since the spiders "are choosy about the various body parts, we assume that they get something like hunger cravings for specific nutrients. It has been shown previously for other predators, including spiders, that they select different types of prey or food according to their nutritional needs."

Pekar, a researcher in the Department of Botany and Zoology at Masaryk University, and his colleagues collected Zodarion spiders a tiny and rarely seen nocturnal arachnid -- from various places in Brno, Czech Republic.

The researchers prepared and nutritionally analyzed different ant meals for the collected spiders. These meals consisted of whole ants, just the gasters (the bulbous-looking main body part), or the heads and appendages.

The scientists then analyzed the choices spiders made when feeding on whole ants, and what the spiders' survival rate was over the study period.

The spiders' survival was significantly affected by which body parts they fed on. The spiders that had to eat entire ants fared worse than spiders that were able to pick and choose ant parts.

That's probably because each of the ant parts provides different nutrients. The legs have a lot of nitrogen, the head has more protein and the gaster is "fattier," with more calories.

Ants may protect their gaster "because it contains defensive chemicals, such as formic acid," Pekar said. That doesn't completely stop spiders from eating it, but the acid makes the gaster less appealing to spiders.

The findings about selective body part feeding apply to certain other spiders, insects and animals, especially those that eat just a handful of species, according to the scientists.

The study has been accepted for publication in the journal Animal Behavior. (ANI)