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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.
Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a spine or backbone), which evolved from the notochord.It is a paraphyletic grouping including all animals excluding the chordate subphylum Vertebrata, i.e. vertebrates.
A tunicate is an exclusively marine invertebrate animal, a member of the subphylum Tunicata (/ ˌ tj uː n ɪ ˈ k eɪ t ə / TEW-nih-KAY-tə).This grouping is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates).
The Cambrian chordates are an extinct group of animals belonging to the phylum Chordata that lived during the Cambrian, between 538 and 485 million years ago. The first Cambrian chordate known is Pikaia gracilens , a lancelet -like animal from the Burgess Shale in British Columbia , Canada.
Phylum Kinetoplastida – Flagellated protists belonging to the phylum Euglenozoa; Alveolata phyla – Superphylum of protists; Phylum Ciliophora – Taxon of protozoans with hair-like organelles called cilia; Phylum Apicomplexa – Phylum of parasitic alveolates; Phylum Dinoflagellata – Aquatic, unicellular protists with two flagella
The lion's mane jellyfish (Cnidaria: Cyanea capillata) is the largest known type of jellyfish. Their tentacles can reach up to 190 feet long, and they may have a bell diameter of almost 7 feet. These animals are usually found in cold northern Arctic waters and in the Northern portions of the Atlantic and Pacific Oceans .
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 ]
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]