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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.
Initially, Deuterostomia included the phyla Brachiopoda, [6] Bryozoa, [7] Chaetognatha, [8] and Phoronida [6] based on morphological and embryological characteristics. However, Deuterostomia was redefined in 1995 based on DNA molecular sequence analyses, leading to the removal of the lophophorates which was later combined with other protostome animals to form the superphylum Lophotrochozoa. [9]
The species is a tetrapod, its four legs adapting the fish-like body plan for walking on land. The specimen is 26 m (85 ft) long. The specimen is 26 m (85 ft) long. As embryos, vertebrates still have a notochord; as adults, all but the jawless fishes have a vertebral column, made of bone or cartilage , instead. [ 7 ]
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.
However, it is now accepted [who?] that it is the vertebrate pharyngeal pouches and not the neck slits that are homologous to the pharyngeal slits of invertebrate chordates. [citation needed] Pharyngeal arches, pouches, and clefts are, at some stage of life, found in all chordates. One theory of their origin is the fusion of nephridia which ...
This change from a body plan for breathing and navigating in gravity-neutral water to a body plan with mechanisms enabling the animal to breath in air without dehydrating and move on land is one of the most profound evolutionary changes known. [18] [19] Tetrapods can be divided into four classes: amphibians, reptiles, birds and mammals.
Segmentation in biology is the division of some animal and plant body plans into a linear series of repetitive segments that may or may not be interconnected to each other. This article focuses on the segmentation of animal body plans, specifically using the examples of the taxa Arthropoda, Chordata, and Annelida. These three groups form ...
A true endoskeleton is derived from mesodermal tissue. In three phyla of animals, Chordata, Echinodermata and Porifera (), endoskeletons of various complexity are found.An endoskeleton may function purely for structural support (as in the case of Porifera), but often also serves as an attachment site for muscles and a mechanism for transmitting muscular forces as in chordates and echinoderms ...