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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.
Well-known phyla of invertebrates include arthropods, mollusks, annelids, echinoderms, flatworms, cnidarians, and sponges. The majority of animal species are invertebrates; one estimate puts the figure at 97%. [1] Many invertebrate taxa have a greater number and diversity of species than the entire subphylum of Vertebrata. [2]
The calcichordate hypothesis, formulated by British Museum paleontologist Richard Jefferies, holds that each separate lineage of chordate (Cephalochordates, Urochordates, Craniates) evolved from its own lineage of mitrate, and thus the echinoderms and the chordates are sister groups, with the hemichordates as an out-group. [1]
Tunicates are the only chordates that have lost their myomeric segmentation, with the possible exception of the seriation of the gill slits. [8] [9] However, doliolids still display segmentation of the muscle bands. [10] Some tunicates live as solitary individuals, but others replicate by budding and become colonies, [11] each unit being known ...
These squid are both the largest known cephalopod and the largest known mollusc. They can grow to a length of about 45–50 feet long. They can grow to a length of about 45–50 feet long. They developed large eyes, the largest of any animal, to be able to detect small amounts of bioluminescence in the dark and deep ocean where they live.
The biological systematics and taxonomy of invertebrates as proposed by Richard C. Brusca and Gary J. Brusca in 2003 is a system of classification of invertebrates, as a way to classify animals without backbones.
The lancelets (/ ˈ l æ n s l ɪ t s, ˈ l ɑː n-/ LA(H)N-slits), also known as amphioxi (sg.: amphioxus / ˌ æ m f i ˈ ɒ k s ə s / AM-fee-OK-səs), consist of 32 described species of "fish-like" benthic filter feeding chordates [9] in the subphylum Cephalochordata, class Leptocardii, and family Branchiostomatidae.
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 ...