Imagine spending another lovely day on the beach when, out of the blue, great forests of foreign seaweed wash ashore. The last thing you'd likely do is say, "hm, I think I'm going to live in this stuff!" Strangely, that's exactly what crabs and other crustaceans are doing, and it's working out really well for them.

A study recently published in the journal Ecology details how the red Japanese seaweed Gracilaria vermiculophylla is gaining a foothold where no native seaweeds live - along the salty mudflats of Georgia and South Carolina.

This region was originally best characterized by only debris from high-tide and patches of dying marsh grass. This made it prime hunting ground for predators who preyed on exposed crabs and tiny shrimp.

However, now these creatures, namely the native crustacean Gammarus mucronatus, is finding shelter among the new seaweed, using it to hide from aquatic predators and birds during high tide, and as a source of shade during the region's hot and dry low tide.

Researchers investigating this unexpected turn of events found that G. mucronatus was up to 100 times as abundant on seaweed invaded mudflats, compared to shorelines devoid of the weed.

And while this sounds like a boon for these innovative crustaceans, it also shows how invasive species can severely impact foodwebs in ways that don't immediately look harmful.

Most invasive plants are easily identified as problem species when they begin to outcompete local flora, choking out the competition and massively disrupting the ecosystem in the process. However, "the story for individual species is more complicated, as the presence of the invader is sometimes a benefit, either as a new source of food or, as in this case, of shelter," the Ecological Society of America said in a recent release.

Nature World News recently reported about a similar case seen in the San Francisco Bay, where the endangered California Clapper Rail actually learned to use a highly invasive cord grass as its new breeding habitats after the invader bullied out the plants that characterized the bird's original habitat.

"Just thinking from a single-species standpoint doesn't work," environmental scientist Alan Hastings said back in May. Flexibility and careful consideration, he says, are key in any battle against invaders.