Carl Linnaeus discovered and described the first siphonophore, the Portuguese man o' war, in 1758. The discovery rate of siphonophore species was slow in the 18th century, as only four additional species were found. During the 19th century, 56 new species were observed due to research voyages conducted by European powers. The majority of new species found during this time period were collected in coastal, surface waters. During the HMS "Challenger" expedition, various species of siphonophores were collected. Ernst Haeckel attempted to conduct a write up of all of the species of siphonophores collected on this expedition. He introduced 46 "new species"; however, his work was heavily critiqued because some of the species that he identified were eventually found not to be siphonophores. Nonetheless, some of his descriptions and figures (pictured below) are considered useful by modern biologists. A rate of about 10 new species discoveries per decade was observed during the 20th century. Considered the most important researcher of siphonophores, A. K. Totton introduced 23 new species of siphonophores during the mid 20th century.