Definition of lancelet in US English:

lancelet

noun

  • A small elongated marine invertebrate that resembles a fish but lacks jaws and obvious sense organs. Lancelets possess a notochord and are among the most primitive chordates.

    Subphylum Cephalochordata, phylum Chordata: several species, including amphioxus

    • ‘As examples, she worked on lampreys in the early sixties, molluscs and lancelet in the early seventies, and teleosts in the early eighties.’
    • ‘In lancelets, the trunk somites extend and fuse ventrally to give the unsegmented periviscelar coelom.’
    • ‘Unlike lancelets, however, Haikouella possessed a small number of pharyngeal bars that may have been composed of mucocartilage, as in modern lampreys.’
    • ‘To tease out the details of the transition, other researchers recently turned to lancelets, vertebrates' closest spineless relatives.’
    • ‘Biologists could examine the many living animals (such as lancelets and sea squirts) that represented stages in the transition from the invertebrates to the earliest jawless fishes.’

Origin

Mid 19th century: from the noun lance (because of its long narrow form) + -let.

Pronunciation

lancelet

/ˈlænslət//ˈlanslət/