KINGDOM: Animals

Bilaterally symmetrical animals

SUPERPHYLUM: Deuterostomes

Deuterostomia is the superphylum where you will find most common zoo animals.

During the very early embryonic development of many animals, some of the cells alter to create an opening within the embryo called a blastopore.  In deuterostomia, the blastopore becomes the anus.

Animals within the superphylum of deuterostomia differ from protostomes where the blastopore becomes the mouth.

In deuterostomes, after the anus has been established, a second opening forms to create the mouth.

The earliest form of known supposed deuterostome is supposedly the genus known as Kimbrella which is believed to have existed 558 to 555 million years ago.  It was originally thought to be a type of jellyfish which is not a bilaterally symmetrical animal like all deuterostomes.

The superphylum of deuterostomes is split into phyla known as chordata, hemichordata, echinodermata, xenoturbellida and the extinct vetulicolia.

The phylum known as chordata contains most common zoo animals.  This is because chordata contain vertebrates (animals with a spine) apart from some exceptions which would have had a major chord within their body at some stage of their development.  Once again, you may wish to skip the following digressions to discover more about more commonly known animals by moving onto the chordates page.

Hemichordata are represented in today's world by animals such as the acorn worm.  They are believed to have some primitive type of notochord, which is believed to be the first type of backbone development in animals some 530 million years ago.

Echinodermata are to be found in the oceans of the world and contain such animals as starfish and sea urchins.  Although as larvae they resemble bilaterally symmetrical animals, they eventually morph into animals with five parts around a central axis at some point during their life, rather like the familiar starfish.

The xenoturbellida has been established as a deuterstome that contains marine worm like species within its phylum.  They have no apparent brain, gonads or excretion system but they do have a nervous system and tail like projections which are commonly known as cilia.

It is presumed that the extinct vetulicolia phylum was an animal that swam, and that it had five gills and a large mouth.  It is also presumed that it had a tail section to its body in seven segments.  Discovery has led researchers to believe that these animals were certainly abundant around China.

Humans are chordates.