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Biology  Determinate growth  Developmental biology

deuterostomes Animals in which the first opening that appears in the embryo becomes the anus while the mouth appears at the other end of the digestive system. Main groups include chordates and echinoderms.

Superb Fairy-wren, Malurus cyaneus
Deuterostomes differ from the other Bilateria, called protostomes, in several ways. In both cases there is a complete digestive tract.

deuterostomes A group of Metazoans that exhibit indeterminate, radial cleavage and that develop a mouth independent of, and at some distance from, the blastopore. (Echinoderms and Chordates and related minor phyla).

deuterostomes - broad classification of triploblastic animals including echinoderms and chordates that tend to share certain embryological traits; among these the formation of the "mouth second" (hence the name) during gastrulation, after the future anus, which is comes from the blastopore, ...

Deuterostomes differ from the other Bilateria, called protostomes, in several ways. In both cases there is a complete digestive tract. However, in protostomes the initial opening (the archenteron) develops into the mouth, and an anus forms separately.

The ~s
The features of these animals are listed above. The most prominent members of this group belong to the echinoderms and the chordates.
Echinoderms (Phylum Echinodermata)
Characteristics: ...

~s, on the other hand, exhibit radial cleavage in which the blastomeres divide perpendicular or parallel to one another and are
Development in protostomes and ~s.

~s Animals in which the anus forms from, or in the region of, the blastopore; often characterized by enterocoelous coelom formation, radial cleavage, and the presence of a dipleurulalike larval stage.

The ~s differ from the Protostomes in various ways. They also have a complete digestive tract, but in this case the archenteron develops into the anus. The mesoderm and coelom do not form in the same way, but rather through evagination of the endoderm called enterocoelic pouching.

Many ~s undergo radial cleavage in which the cleavage planes are parallel or perpendicular to the vertical egg axis.
Most ~s show indeterminate cleavage, whereby each cell in the early embryo retains the capacity to develop into a complete embryo.

There is a widespread perception that ecdysozoans have lost more of the ancestral gene set than have ~s or lophotrochozoans.

(B) A maximum-likelihood phylogeny of ATP6AP-related genes based on protein alignments and rooted to ~s (not shown). Branch numbers indicate bootstrap support; gene losses (in birds and mammals) are in red.

Digestive system: complete, ~s. Respiratory system: branchial (in aquatic), cutaneous (in adult amphibians), pulmonary (others). Circulatory system: open in protochordates, closed in vertebrates. Excretory system: diffusion and flame cells in protochordates, kidneys in vertebrates.

A type of embryonic development in ~s, in which each cell produced by early cleavage divisions retains the capacity to develop into a complete embryo.
indeterminate growth
A type of growth characteristic of plants, in which the organism continues to grow as long as it lives.

Pascual-Anaya, J., D'Aniello, S., Kuratani, S. & Garcia-Fernandez, J. (2013). Evolution of Hox gene clusters in ~s. BMC Developmental Biology, 13(26). doi:10.1186/1471-213X-13-26 ...

See also: See also: What is the meaning of Animal, Cells, Organ, Character, Species?

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