This image above represents a basic Eukaryotic cell. However, not all the organisms cells have all of these organelles, they have even more complex structures than others, including cell walls. The key point is that the cell contains a nucleus.
Eukarya started off with different kingdoms then the kingdoms we have today. The plantae and the fungi started off as the same kingdom, but over time the differences between them were recognized and the two were then separated. This separation wasn't fully understood until the 1980s. All the single-celled organisms were originally placed in the kingdoms Animalia and Plantae. In the 1830s a German scientist realized this, and made the kingdom Protista. 
The earliest fossil from an animal that was found was 650 to 544 million years ago. Then the first mass extinction occurred. After this,known as the Cambrian Period, evolutionary radiation happened and the production of the most of the major phyla were made.
The Domain Eukarya is the only Domain that consist of organisms that eukaryote. This means organisms with complex structures within complex membranes. The difference between eukaryotic cells and prokaryotic cells is that eukaryotes have a nucleus. Within the cell there are organelles, for example the mitochondria, and the Golgi apparatus. This Domain contains 4 different kingdoms including Protista, Fungi, Plantae, and Animalia. 
Click on an organism below to learn tow different organisms that are classified in this Domain.
To learn more about to the different kingdoms of the Domain Eukarya, push the button below :)