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A chordate (/ ˈ k ɔːr d eɪ t / KOR-dayt) is a deuterostomal bilaterian animal belonging to the phylum Chordata (/ k ɔːr ˈ d eɪ t ə / kor-DAY-tə).All chordates possess, at some point during their larval or adult stages, five distinctive physical characteristics (synapomorphies) that distinguish them from other taxa.
The dorsal nerve cord is an anatomical feature found in chordate animals, mainly in the subphyla Vertebrata and Cephalochordata, as well as in some hemichordates.It is one of the five embryonic features unique to all chordates, the other four being a notochord, a post-anal tail, an endostyle, and pharyngeal slits.
Idealised vertebrate body plan, showing key characteristics [6] Vertebrates (and other chordates) belong to the Bilateria, a group of animals with mirror symmetrical bodies. [7] They move, typically by swimming, using muscles along the back, supported by a strong but flexible skeletal structure, the spine or vertebral column. [6]
The body segments are anatomically blocks of skeletal muscles, called the myomeres, which are found in vertebrates only. No eyes can be observed. [24] The muscle orientation and flat shaped body indicate that Pikaia was an active and free swimmer. [8] It would have swum by throwing its body into a series of S-shaped, zigzag curves, as do living ...
Modern groups of animals can be grouped by the arrangement of their body structures, so are said to possess different body plans. A body plan , Bauplan ( pl. German : Baupläne ), or ground plan is a set of morphological features common to many members of a phylum of animals . [ 1 ]
The dorsal nerve cord serves as a hollow-like backbone where signals are sent throughout the body due to nervous tissue being located in this region. [2] The notochord is also toward the tail of the chordate but closer toward the middle of the body than the dorsal nerve cord and is a water-filled structure that allows the chordate to move in ...
The notochord is the defining feature (synapomorphy) of chordates, and was present throughout life in many of the earliest chordates. Although the stomochord of hemichordates was once thought to be homologous or from a common lineal origin, it is now viewed as analogous, convergent , or from a different lineal origin. [ 22 ]
Lancelets have four known kinds of light-sensing structures: Joseph cells, Hesse organs, an unpaired anterior eye and lamellar body, all of which utilize opsins as light receptors. All of these organs and structures are located in the neural tube, with the frontal eye at the front, followed by the lamellar body, the Joseph cells, and the Hesse ...