Dictionary > Amniote

Amniote

Definition
noun, plural: amniotes
Any of the tetrapod vertebrates belonging to Amniota in which an amnion is formed during its embryonic or fetal stage
Supplement
Amniotes belong to a clade of animals, Amniota, to distinguish them from other vertebrates that are referred to as anamniotes. The amniotes have an amnion during their embryonic or fetal stage in contrast to anamniotes that do not. Amnion is one of the extraembryonic membranes that form and surround the embryo or fetus. The amnion is a thin and a tough membrane and lines the amniotic cavity. It is comprised of two cell layers: the epiblast-derived extraembryonic ectodermal layer and the thin non-vascular extraembryonic mesoderm. It is derived from trophoblasts by folding or splitting.1 Together with the chorion, the amnion forms the amniotic sac. Inside the sac is an amniotic fluid that keeps the fetus afloat and thereby preventing physical injuries. The amnion also serves to transport oxygen into the egg as well as expel carbon dioxide.
Examples of amniotes are reptiles, birds, and mammals. The reptiles and birds lay eggs on land where the latter hatch in time. The mammals retain their fertilized egg inside the uterus where the embryo develops into a fetus and is delivered alive at birth.
Word origin: Greek amnion, amnos (lamb)
Scientific classification:

  • Kingdom: Animalia
  • Phylum: Chordata
  • Superclass: Tetrapoda
  • Clade: Reptiliomorpha
  • Clade: Amniota 1866

Compare:

See also:


You will also like...

Crossing Over and Genetic Diversity
Inheritance and Probability

Gregor Mendel, an Austrian monk, is most famous in this field for his study of the phenotype of pea plants, including ..

Genetics – Lesson Outline & Worksheets
Genetics – Lesson Outline & Worksheets

  Topics Modules Quizzes/Worksheets Description Introduction to Genetics Genetics – Definition: Heredity and ..

Chromosome Mutations
Chromosome Mutations

Mutations can also influence the phenotype of an organism. This tutorial looks at the effects of chromosomal mutations, ..

Adaptive Radiation
Adaptive Radiation

The diversification of several new species from a recent ancestral source, each adapted to utilize or occupy a vacant ad..

Types and Causes of Brain Damage
Types and Causes of Brain Damage

This tutorial describes the different types and causes of brain damage. Find out how genetics, physical injury, lack of ..

Control of body movement
Control of Body Movement

Some of the body movements can be controlled at will, others cannot. The body has a motor program, which is the pattern ..

Related Articles...

No related articles found

See all Related Topics