![]() ![]() In modern times, the biological classification of animals relies on advanced techniques, such as molecular phylogenetics, which are effective at demonstrating the evolutionary relationships between taxa. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa (now synonymous with Animalia) and the Protozoa, single-celled organisms no longer considered animals. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. Historically, Aristotle divided animals into those with blood and those without. 6,331 groups of genes common to all living animals have been identified these may have arisen from a single common ancestor that lived 650 Mya during the Cryogenian period. Nearly all modern animal phyla became clearly established in the fossil record as marine species during the Cambrian explosion, which began around 539 million years ago (Mya), and most classes during the Ordovician radiation 485.4 Mya. Precambrian life forms interpreted as early complex animals were already present in the Ediacaran biota of the late Proterozoic, but fossils of primitive sponge and other speculative early animals have been dated to as early as the Tonian period. and the deuterostomes, which include the three phyla echinoderms, hemichordates and chordates, the latter with the vertebrates being its most successful subphylum. Extant bilaterians include the basal group Xenacoelomorpha, but the vast majority belong to two large superphyla: the protostomes, which include phyla such as arthropods, molluscs, flatworms, annelids and nematodes, etc. Most living animal species belong to the infrakingdom Bilateria, a highly proliferative clade whose members have a bilaterally symmetric body plan. The scientific study of animals is known as zoology, and the study of animal behaviors is known as ethology. They have complex ecologies and interactions with each other and their environments, forming intricate food webs. It has been estimated there are as many as 7.77 million animal species on Earth. With few exceptions, animals consume organic material, breathe oxygen, have myocytes and are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development.Īs of 2022, around 2.16 million living animal species have been described-of which around 1.05 million are insects, over 85,000 are molluscs, and around 65,000 are vertebrates. Download the file so you can return to the lesson if necessary.Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. Color the eyes black and add highlights.Īs usual, at the end of the lesson, I prepared a PDF file for you, which contains a simplified version of the guide and additional useful materials. On the right side, draw a long, rounded line from the end of the trunk to the eye.ĭraw the small hole at the end of the trunk and add folds to the surface of the trunk.ĭraw smooth lines along the outer edge of each ear. Depict a rounded shape that has a narrow top and a wide side.īe careful in this step and try to depict the curve of the trunk correctly. ![]()
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