[7][8][9] Clapp would later call her time at Penikese "an opening of doors," where she first encountered a community of people deeply engaged with biological research and theory.

[15] After graduating from Mount Holyoke, Clapp spent a year as a Latin teacher at a boys' boarding school, Potter Hall, in Andalusia, Pennsylvania.

Additionally, along with other New England entomologists, Clapp collected insects from the White Mountains of New Hampshire in the summer of 1875, as well as from various mid-Atlantic states, including the Johns Hopkins University marine station in Beaufort, South Carolina and the Smithsonian Institution in Washington, D.C., in 1877.

[1][17] In 1888, Clapp began her affiliation with the Marine Biological Laboratory (MBL) during its inaugural session, where she was the first researcher to be assigned a topic of investigation - the lateral line of the toadfish.

[5] Although she was primarily known as an educator and authored few scientific research papers, she was ranked one of the top 150 zoologists in the U.S. by a 1903 study reported in American Men of Science.

The rest of the committee was composed entirely of men, including ichthyologist David Starr Jordan, entomologist Leland O. Howard, and geneticist Edmund B.

In that role, she initiated an exchange program whereby the MBL sent out its Biological Bulletin and received other international journals in return, which over time added up to a magnificent collection.

[29] Her work on the toadfish was instrumental in correcting the idea that its egg was attached by a "sucker" to the yolk stalk, as she discovered that it was instead adhered with a disc of "transparent secretion" that could be separated from the membrane.

[30] For example, one of her students and assistants, Louise B. Wallace, wrote an article building upon Clapp's toadfish research[12][31] that was published in an 1898 issue of the Journal of Morphology.