page_title: Chordate
section_title: Subphyla
hierarchical_section_title: Chordate / Subphyla
caption_attribution_description: Branchiostoma lanceolatum (Pallas, 1774) English: A Lancelet (or Amphioxus) specimen —Subphylum: Cephalochordata— collected in coarse sand sediments (600 µm) on the Belgian continental shelf. Total Length: approximately 22 mm. Geo-location not applicable as the picture was taken in the laboratory. Français&#160;: Un spécimen de lancelet (ou amphioxus) —Subphylum: Cephalochordata— récolté dans des sédiments de sable grossier (600 µm) sur le Plateau continental belge. Longueur totale: 22 mm environ. Géo-localisation non applicable parce que la photo a été prise dans le laboratoire.
context_page_description: A chordate is an animal of the phylum Chordata. During some period of their life cycle, chordates possess a notochord, a dorsal nerve cord, pharyngeal slits, and a post-anal tail: these four anatomical features define this phylum. Chordates are also bilaterally symmetric, and have a coelom, metameric segmentation, and circulatory system.
  The Chordata and Ambulacraria together form the superphylum Deuterostomia. Chordates are divided into three subphyla: Vertebrata; Tunicata or Urochordata; and Cephalochordata. There are also extinct taxa such as the Vetulicolia. Hemichordata has been presented as a fourth chordate subphylum, but now is treated as a separate phylum: hemichordates and Echinodermata form the Ambulacraria, the sister phylum of the Chordates. Of the more than 65,000 living species of chordates, about half are bony fish that are members of the superclass Pisces, class Osteichthyes.
  Chordate fossils have been found from as early as the Cambrian explosion, 541 million years ago.
caption: Cephalochordate: Lancelet
exif: {}