American pioneer and explorer Daniel Boone surely appreciated a great nature mystery. As a keen observer of flora and fauna, he understood that “Curiosity is natural..and interesting objects have a powerful influence on our affections.”

Nature is full of curiosities and interesting objects. Two natural mysteries had my attention last week. The first was the crab conundrum. Reports came into the sanctuary of large numbers of spider crabs along the Island’s North Shore, Menemsha and in some of our ponds.

One inquirer shared her experience: “For the first time ever in my 48 years I looked down at my feet in the shallows and saw five surprisingly agile spider crabs aiming themselves quite eagerly toward my toes! I have never seen them there before . . . is there an increase in their numbers on the Vineyard?”

Seasonal changes in species diversity are common and there are a few possible reasons for the noticeable increase in spider crabs reported this season, though without more study it is not possible to have a definitive answer.

Spider crabs will aggregate during mating and molting for safety. They are also a pollution tolerant species and can live in waters with diminished water quality. So as water bodies are impacted, their numbers may hold steady and even increase as other wildlife diminishes.

Another factor is competition. Invasive green crabs outcompete and are predators of spider crabs. Perhaps there was less competition from these aggressors. Changes in salinity might also be a possibility, since spider crabs can’t tolerate large changes in salinity, so congregate in areas with stable salt content.

And since conditions can change rapidly, next week may bring a completely different set of observations.

The other marine mystery was the arrival of goose or stalked barnacles on the south shore of the Vineyard. Stalked barnacles differ from the more recognizable and common sessile barnacles, which are seen on piers, boats, shells and rocks and sometimes make walking barefoot treacherous.

Gooseneck barnacles can be both pelagic, spending time in the open ocean, or intertidal, living near the shore, though they tend to be more pelagic in our environs. These less commonly seen barnacles are more mobile than their scratchy white cousins as they attach themselves to seaweed and other floating debris natural or otherwise.

Fascination with barnacles has engaged and enraged some of the most famous scientists. Darwin spent over eight years studying them, eventually completing a four-volume set exclusively on these odd creatures, after which he was quoted as stating he “hates a barnacle as no man ever did.”

His frustration was directed at a barnacle he named Mr. Arthrobalanus, a burrowing species collected during his voyage on the ship Beagle and his confusion regarded how they live, reproduce and where they belong in the scientific classification system.

If as Nobel Prize winning American Linus Pauling believed that “Satisfaction of one’s curiosity is one of the greatest sources of happiness in life,” then after his long years of obsession, Darwin must have been quite pleased with his final work.

And even if we have uncovered the answers to the most recent natural mysteries, there is no need to rest on our laurels. Author Anaïs Nin explained, “The possession of knowledge does not kill the sense of wonder and mystery. There is always more mystery.”

Suzan Bellincampi is director of the Felix Neck Wildlife Sanctuary in Edgartown, and author of Martha’s Vineyard: A Field Guide to Island Nature.