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All chordates are deuterostomes. This means that, during embryonic development, the anus forms before the mouth does. All chordates are based on a bilateral body plan. [15] All chordates are coelomates, and have a fluid-filled body cavity with a complete serosal lining derived from mesoderm called mesothelium (see Brusca and Brusca). [16]
This article contains a list of all of the classes and orders that are located in the Phylum Chordata. The subphyla Tunicata and Vertebrata are in the unranked Olfactores clade, while the subphylum Cephalochordata is not. Animals in Olfactores are characterized as having a more advanced olfactory system than animals not in it.
This process is called enterocoely. Another feature present in both the Hemichordata and Chordata is pharyngotremy — the presence of spiracles or gill slits into the pharynx, which is also found in some primitive fossil echinoderms . [17] [18] A hollow nerve cord is found in all chordates, including tunicates (in the larval stage). Some ...
Vertebrates share these characteristics with other chordates. [4] Vertebrates are distinguished from all other animals, including other chordates, by multiple synapomorphies, namely the vertebral column; skull of bone or cartilage, large brain divided into 3 or more sections, a muscular heart with multiple chambers; an inner ear with ...
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 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).
A craniate is a member of the Craniata (sometimes called the Craniota), a proposed clade of chordate animals with a skull of hard bone or cartilage.Living representatives are the Myxini (hagfishes), Hyperoartia (including lampreys), and the much more numerous Gnathostomata (jawed vertebrates).
Molecular studies by molecular systematists, based on DNA analysis, in the early 21st century have revealed new relationships among mammal families. Classification systems based on molecular studies reveal three major groups or lineages of placental mammals, Afrotheria, Xenarthra, and Boreoeutheria. which diverged from early common ancestors in the Cretaceous.