According to some recent findings, humans may not be the only animals who enjoy a side dish to go with their main meat entrée. A team at the University of Exeter found that orb web spiders sometimes actually choose to eat pollen even when insects are plentiful.

Dirk Sanders, an ecologist at the University of Exeter, teamed up with Benjamin Eggs from the University of Bern to conduct a series of feeding experiments on juvenile spiders. They supplemented this experiment with a stable isotope analysis and compiled both bits of information to determine whether or not spiders do in fact eat vegetation in order to supplement their diets.

The research team found an astonishing 25 percent of the young spiders’ diet came from pollen. The other 75 percent of their diet comprised insects.

“Most people and researchers think of spiders as pure carnivores, but in this family of orb web spiders that is not the case,” said Sanders. “We have demonstrated that the spiders feed on pollen caught in their webs, even if they have additional food, and that it forms an important part of their nourishment.”

The team also found that while the spiders use webs to capture their prey, the webs also act as nets to collect floating pollen.

“The question remains whether spiders choose their web building location based on pollen availability in the environment,” the researchers said. “The juvenile (orb-weaving spiders) we observed in this study had built their webs in the branchwood of different wind-pollinated trees. This could be due to the fact that these are optimal locations for successfully capturing flying insect prey; however it could also be possible that webs are positioned according to pollen availability and spiders select these locations as juveniles.”

The consumption of these captured pollens, the team concluded, could not have been by mistake.

“Most pollen grains are too large to pass through the spider’s pharynx and therefore cannot be swallowed accidentally but have to be actively consumed,” the researchers concluded. “Spiders dissolve the outer coating of a pollen grain via extra-oral digestion and suck up the dissolved nutrients afterwards.”

The team provided their young spiders with different types of diets, and they found no weight variance among the arachnids. They found that pollen may not be important for growth but rather for overall long-term fitness such as reproduction and survival.

“Further studies investigating pollen feeding at different life stages and in different habitats are needed to increase our understanding of the importance of herbivory for spider fitness, behavior and their role in ecological communities,” they concluded.