Animal

Animaliaanimalsmetazoametazoanmetazoansanimal kingdomcreaturecreaturesbeastkingdom Animalia
Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia.wikipedia
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Multicellular organism

multicellularmulticellular organismsmulticellularity
Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia.
All species of animals, land plants and most fungi are multicellular, as are many algae, whereas a few organisms are partially uni- and partially multicellular, like slime molds and social amoebae such as the genus Dictyostelium.

Heterotroph

heterotrophicheterotrophsheterotrophy
With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development.
Living organisms that are heterotrophic include all animals and fungi, some bacteria and protists, and parasitic plants.

Eukaryote

Eukaryotaeukaryoticeukaryotes
Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia.
Animals and plants are the most familiar eukaryotes.

Human

humanshuman beinghuman beings
The kingdom Animalia includes humans, but in colloquial use the term animal often refers only to non-human animals.
A terrestrial animal, humans are characterized by their erect posture and bipedal locomotion; high manual dexterity and heavy tool use compared to other animals; open-ended and complex language use compared to other animal communications; larger, more complex brains than other animals; and highly advanced and organized societies.

Bilateria

bilaterianbilateriansbilateral animals
Most living animal species are in the Bilateria, a clade whose members have a bilaterally symmetric body plan.
The bilateria or bilaterians are animals with bilateral symmetry as an embryo, i.e. having a left and a right side that are mirror images of each other.

Invertebrate

invertebratesmacroinvertebratemacroinvertebrates
The Bilateria include the protostomes—in which many groups of invertebrates are found, such as nematodes, arthropods, and molluscs—and the deuterostomes, containing both the echinoderms as well as the chordates, the latter containing the vertebrates.
Invertebrates are animals that neither possess nor develop a vertebral column (commonly known as a backbone or spine), derived from the notochord.

Kingdom (biology)

kingdomkingdomssubkingdom
Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia.
Traditionally, some textbooks from the United States and Canada used a system of six kingdoms (Animalia, Plantae, Fungi, Protista, Archaea/Archaebacteria, and Bacteria/Eubacteria) while textbooks in countries like Great Britain, India, Greece, Brazil and other countries used five kingdoms (Animalia, Plantae, Fungi, Protista and Monera).

Embryonic development

embryogenesisdevelopmentembryo development
With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development.
Although embryogenesis occurs in both animal and plant development, this article addresses the common features among different animals, with some emphasis on the embryonic development of vertebrates and mammals.

Zoology

zoologistzoologicalzoologists
The study of non-human animals is known as zoology.
Zoology is the branch of biology that studies the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems.

Blastula

blastulationblastula stage
With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development.
The blastula (from Greek βλαστός (blastos), meaning "sprout") is a hollow sphere of cells, referred to as blastomeres, surrounding an inner fluid-filled cavity called the blastocoele formed during an early stage of embryonic development in animals.

Marine life

marinemarine animalsea life
Many modern animal phyla became clearly established in the fossil record as marine species during the Cambrian explosion, which began around 542 million years ago.
Marine life, or sea life or ocean life, is the plants, animals and other organisms that live in the salt water of the sea or ocean, or the brackish water of coastal estuaries.

Sexual reproduction

sexuallysexualreproduce sexually
With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development.
Cell division mitosis then initiates the development of a new individual organism in multicellular organisms, including animals and plants, for the vast majority of whom this is the primary method of reproduction.

Cambrian explosion

Cambrian radiationCambrian invertebratesCambrian transition
Many modern animal phyla became clearly established in the fossil record as marine species during the Cambrian explosion, which began around 542 million years ago.
It lasted for about 13 – 25 million years and resulted in the divergence of most modern metazoan phyla.

Ediacaran biota

Ediacara biotaEdiacaranEdiacaran fauna
Life forms interpreted as early animals were present in the Ediacaran biota of the late Precambrian.
Most of the currently existing body plans of animals first appeared in the fossil record of the Cambrian rather than the Ediacaran.

Motility

motilenonmotilenon-motile
With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development.
In addition to animal locomotion, most animals are motile (some move by passive locomotion).

Meat

meatsmeat consumptionlean meat
Humans make use of many other animal species for food, including meat, milk, and eggs; for materials, such as leather and wool; as pets; and as working animals for power and transport.
Meat is animal flesh that is eaten as food.

Protozoa

protozoanprotozoanspellicle
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.
Historically, the protozoa were regarded as "one-celled animals", because they often possess animal-like behaviors, such as motility and predation, and lack a cell wall, as found in plants and many algae.

Phylum

phyladivisionsuperphylum
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.
Depending on definitions, the animal kingdom Animalia or Metazoa contains approximately 35 phyla, the plant kingdom Plantae contains about 14, and the fungus kingdom Fungi contains about 8 phyla.

Pet

petscompanion animalscompanion animal
Humans make use of many other animal species for food, including meat, milk, and eggs; for materials, such as leather and wool; as pets; and as working animals for power and transport.
A pet, or companion animal, is an animal kept primarily for a person's company, entertainment or as an act of compassion such as taking in and protecting a stray cat, rather than as a working animal, livestock or laboratory animal.

Symmetry in biology

bilateral symmetryradial symmetrybilaterally symmetrical
Most living animal species are in the Bilateria, a clade whose members have a bilaterally symmetric body plan.
Symmetry was once important in animal taxonomy; the Radiata, animals with radial symmetry, formed one of the four branches of Georges Cuvier's classification of the animal kingdom.

Systema Naturae

1758Systema Naturæ1789
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.
In it, he outlined his ideas for the hierarchical classification of the natural world, dividing it into the animal kingdom (regnum animale), the plant kingdom (regnum vegetabile), and the "mineral kingdom" (regnum lapideum).

Cell junction

intercellular junctionsjunctional complexcell junctions
Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, and desmosomes.
A cell junction (or intercellular bridge ) is a type of structure that exists within the tissues of animals.

Gastrulation

gastrulablastoporedorsal lip
It first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm.
Gastrulation is a phase early in the embryonic development of most animals, during which the single-layered blastula is reorganized into a multilayered structure known as the gastrula.

Meiosis

meioticsyzygymeiosis I
They produce haploid gametes by meiosis; the smaller, motile gametes are spermatozoa and the larger, non-motile gametes are ova.
This process occurs in all sexually reproducing single-celled and multicellular eukaryotes, including animals, plants, and fungi.

Germ layer

germ layersmesodermectoderm
It first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm.
The three germ layers in vertebrates are particularly pronounced; however, all eumetazoans (animals more complex than the sponge) produce two or three primary germ layers.