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vertebrate





Any of a subphylum (Vertebrata) of chordates having individual disks of bone or cartilage called vertebra surrounding or replacing the embryonic notochord ti form a jointed backbone that encloses the spinal column. Vertebrates include: Vertebrates differ from other chordates in having a skull, which surrounds a well-developed brain, and a skeleton of bone or cartilage. Other distinctive features of vertebrates include:
  • Skin with two layers, including an outer epidermis and an inner dermis, often modified to produce hair, scales, feathers, glands, horn, etc.
  • Movements provided by muscles attached to an endoskeleton
  • A digestive system with large digestive glands, a liver, and a pancreas
  • A ventral heart with 2–4 chambers
  • Blood with red blood corpuscles containing hemoglobin, and in addition, white corpuscles
  • Paired kidneys with ducts to drain waste to exterior
  • Two sexes, each with paired gonads (there are some exceptions)
  • A general body plan consisting of head, trunk, two pairs of appendages, and post anal tail (though these structures are highly modified in many vertebrates and sometimes absent).
Vertebrates have existed on Earth for more than 500 million years, from the late Cambrian to the present day. The first vertebrates lacked jaws, like the living hagfish and lampreys. Jawed vertebrates appeared 100 million years later, in the Silurian.


Related entry

   • vertebrate nervous system


Related category

   • ZOOLOGY