Phylum Craniata of the Kingdom Animalia

The distinguishing feature of all 45,000 species in the phylum Craniata is a brain encased in a cranium or skull that also protects the eyes and inner ears. During development, the brain and spine form from a a dorsal nerve cord that is supported by a cartilaginous notochord. Gill slits are eventually lost or modified to serve other functions in terrestrial craniates, but they are retained in many aquatic caraniates such as the lampreys. All craniates are bilaterally symetrical and have a well-developed coelom, a body cavity, derived from the middle layer of embryonic tissues. The coelom houses the internal organs in the adult. The simplest craniate animals are jaw-less fishes with cartilage skeletons. The first craniates were jawless fishes and are first observed in the fossil record about 480 million years ago. More complex craniates, including all the terrestrial forms have well formed jaws and a bony skeleton. Click here for more information.

Craniata Groups

• Superclass Agnatha
  • Class Cyclostomata (lampreys, hagfish)
• Superclass Gnathostomata
  • Chondricthyes (sharks, skates, and rays)
  • Osteichthyes (bony fish)
  • Choanichthyes (lungfish)
  • Amphibia (salamanders, frogs, sirens)
  • Reptilia (turtles, lizards, snakes)
  • Aves (birds)
  • Mammalia (mammals)

Biodiversity Topics: Introduction . Plants . Animals . Mammals . Birds . Reptiles & Amphibians . Arthropods . Spiders . Insects

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Last updated on January 12, 2006