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Green Barrel Colonial Tunicates. Scott W. Michael

[edit] The Chordates

Tunicates and True Vertebrates

Number of Living Species: 44,000.

Common Characteristics: members of the large Subphylum Vertebrata (true vertebrates), have a segmented backbone that protects a spinal cord; two small subphyla, including the tunicates or sea squirts, have a notochord (a hollow dorsal tube analogous to a true spinal cord) during part of their life cycle. These latter groups are generally lumped with the invertebrates.

Noteworthy Behaviors: true vertebrates have evolved some of the most complex anatomies, motor skills, intelligences, and behaviors in the Animal Kingdom.

They are Earth’s apex predators (although some biologists point out that the sheer mass and enormous molecular diversity of bacteria make them the dominant life forms on our planet).

Subphylum Urochordata (Tunicates): 1,600 species

Class Ascidiacea (Sea Squirts)

Class Thaliacea (Salps, Pyrosomes)

From: Reef Life by Denise Nielsen Tackett