cephalochordate, any of more than two dozen species belonging to the subphylum Cephalochordata of the phylum Chordata. Small, fishlike marine invertebrates, they probably are the closest living relatives of the vertebrates. Cephalochordates and vertebrates have a hollow, dorsal nerve cord, pharyngeal gill slits, and a notochord.

According to this theory, there is a deep agreement between the vertebrates and cephalochordates, and even all chordates. [ 75 ] [ 76 ] With the advent of molecular genetics lancelets are once again regarded as a model of vertebrate ancestors, and are used again as a model organism.

2023年11月28日 · Cephalochordata (Gr., kephale, head; chorde, cord) is a sub-phylum within the phylum Chordata. The animals in this group are small, marine invertebrates. They are commonly called lancelets or amphioxi. Cephalochordates show many typical chordate features, including a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.

Known as lancelets or as amphioxus (from the Greek for "both [ends] pointed," in reference to their shape), cephalochordates are small, eel-like, unprepossessing animals that spend much of their time buried in sand.

2024年4月12日 · Cephalochordates, also known as lancelets, are small, fish-like translucent marine chordates found in shallow temperate and tropical oceans, typically buried in coarse sand. They possess several distinct characteristics that are …

The cephalochordates make plausible models for the common ancestor of the chordates and for precursors to vertebrates. They evidently represent a collateral branch on the vertebrate lineage that has been somewhat modified since common ancestry, however, and should not be thought of as a human ancestor.

Cephalochordata is a subphylum in the phylum chordata. The animals belonging to this subphylum are known as cephalochordates, lancelets or amphioxus. They are marine animals that possess a segmented and elongated body. They also contain a notochord that extends from the head to the tail.

Cephalochordata (or lancelets, traditionally known as amphioxus, plural amphioxi) is a subphylum of marine invertebrates of the phylum Chordata. They are usually found in shallow parts of temperate or tropical seas.

The general pattern of blood circulation through vessels and tissues in cephalochordates is strikingly like that of vertebrates, although simpler. The most notable difference is that cephalochordates lack a heart.

The cephalochordates make conceivable models for the regular progenitor of the chordates and forerunners to vertebrates. They address a guarantee branch on the vertebrate genealogy that has been fairly altered since regular heritage, nonetheless, and ought not to be considered as a human precursor.