In the classical era, Aristotle divided animals,d based on his own observations, into those with blood (roughly, the vertebrates) and those without. The chordates are dominated by the vertebrates (animals with backbones), which consist of fishes, amphibians, reptiles, birds, and mammals. Most protostomes have schizocoelous development, where cells simply fill in the interior of the gastrula to form the mesoderm. Most appear to belong to two major lineages, the protostomes and the deuterostomes.
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. The animal kingdom is divided into five major clades, namely Porifera, Ctenophora, Placozoa, Cnidaria and Bilateria. Animals consume organic material, breathe oxygen, have muscle cells, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development.
The Jinshin War of 672, a bloody conflict between Prince Ōama and his nephew Prince Ōtomo, became a major catalyst for further administrative reforms. The true aim of the reforms was to bring about greater centralization and to enhance the power of the imperial court, which was also based on the governmental structure of China. It nationalized all land in Japan, to be distributed equally among cultivators, and ordered the compilation of a household registry as the basis for a new system of taxation.

Bluetick Coonhound

The United States is a major market for Japanese exports and a major source of Japanese imports, and is committed to defending the country, with military bases in Japan. Ambulacraria are exclusively marine and include acorn worms, starfish, sea urchins, and sea cucumbers. Karate, which originated in the Ryukyu Kingdom, is popular across the world and has been included in the Olympic Games. Japan has one of the world’s highest suicide rates, which is considered a major social issue. Minority ethnic groups in the country include the indigenous Ainu and Ryukyuan people. Since privatization in 1987, dozens of Japanese railway companies compete in regional and local passenger transportation markets; major companies include seven JR enterprises, Kintetsu, Seibu Railway and Keio Corporation.
EX Extinct EW Extinct in the Wild CR Critically Endangered EN Endangered VU Vulnerable NT Near Threatened LC Least Concern Oak Toad Oarfish Ocean Perch Ocean Pout Ocean Whitefish Oceanic Whitetip Shark Ocellated Turkey Ocelot Octopus Oenpelli python Oilfish Okapi Old English Sheepdog Old House Borer Oleander Hawk Moth Olingo Olive Baboon Olive python Olive Sea Snake Olm Olympic Marmot Onagadori Chicken Onager Opabinia Opah Opaleye (Rudderfish) Opossum Oranda Goldfish Orange Baboon Tarantula Orange Dream Ball Python Orange Roughy Orange Spider Orange Tanager (Orange-Headed Tanager) Orange-Crowned Warbler Orangutan Orb Weaver Orchard Oriole Orchid Dottyback Oregon Spotted Frog Ori-Pei Oribi Oriental Cockroach Oriental Dwarf Kingfisher Orinoco Crocodile Ornate Bichir Ornate Black-Tailed Rattlesnake Ornate Box Turtle Ornithocheirus Ornithomimus Ortolan Bunting Oscar Fish Osprey Ostracod Ostrich Otter Otterhound Ovenbird Oviraptor Owl Owl Butterfly Owlfly (Ascalaphidae) Ox Oxpecker Oyster Oyster Toadfish Ozark Bass Major animal paintings include Albrecht Dürer’s 1515 The Rhinoceros, and George Stubbs’s c. Some medicines such as the cancer drug trabectedin are based on toxins or other molecules of animal origin.

Crappie Fish

In contrast, the cells of other multicellular organisms (primarily algae, plants, and fungi) are held in place by cell walls, and so develop by progressive growth. Development in Bilateria and Cnidaria is controlled by Hox genes, which signal the times and places to develop structures such as body segments and limbs. The biological definition includes all members of the kingdom Animalia. Non-human animals are also an important element of human culture, having appeared in cave arts and totems since the earliest times, and are frequently featured in mythology, religion, arts, literature, heraldry, politics, and sports.

• The animal kingdom is divided into five major clades, namely Porifera, Ctenophora, Placozoa, Cnidaria and Bilateria.
• People without insurance through employers can participate in a national health insurance program administered by local governments.
• The United States is a major market for Japanese exports and a major source of Japanese imports, and is committed to defending the country, with military bases in Japan.
• Japan has the second highest number of researchers in science and technology per capita in the world with 14 per 1000 employees.
• Nihon is typically used in everyday speech and reflects shifts in Japanese phonology during the Edo period.

After being defeated in the Pacific War and suffering the U.S. atomic bombings of Hiroshima and Nagasaki, Japan surrendered in 1945 and came under Allied occupation until 1952. The Meiji period saw Japan pursue rapid industrialization, modernization, militarism, and overseas colonization. Between the 4th and 6th centuries, its kingdoms were united under an emperor in Nara and later in Heian-kyō. With a population of almost 123 million as of 2026, it is the world’s 11th most populous country.

Foreign relations

• Ambulacraria are exclusively marine and include acorn worms, starfish, sea urchins, and sea cucumbers.
• The scarab beetle was sacred in ancient Egypt, and the cow is sacred in Hinduism.
• The Pacific coast features a humid subtropical climate that experiences milder winters with occasional snowfall and hot, humid summers because of the southeast seasonal wind.
• The country’s five main islands, from north to south, are Hokkaido, Honshu, Shikoku, Kyushu and Okinawa.
• These fuse to form zygotes, which develop via mitosis into a hollow sphere, called a blastula.

For instance, around 25,000–27,000 species of nematodes have been described, while published estimates of the total number of nematode species include 10,000–20,000; 500,000; 10 million; and 100 million. The following table lists estimated numbers of described extant species for the major animal phyla, along with their principal habitats (terrestrial, fresh water, and marine), and free-living or parasitic ways of life. The blue whale (Balaenoptera musculus) is the largest animal that has ever lived, weighing up to 190 tonnes and measuring up to 33.6 metres (110 ft) long. Vertebrates such as the lobe-finned fish Tiktaalik started to move on to land in the late Devonian, about 375 million years ago. Some benthic animals living close to hydrothermal vents and cold seeps on the dark sea floor consume organic matter produced through chemosynthesis (via oxidising inorganic compounds such as hydrogen sulfide) by archaea and bacteria.

Red-Billed Quelea Bird

It consists of a lower House of Representatives with 465 seats, elected by popular vote every four years or when dissolved, and an upper Senate with 248 seats, whose popularly elected members serve six-year terms. More recent major quakes are the 1995 Great Hanshin earthquake and the 2011 Tōhoku earthquake, which triggered a large tsunami. From the 12th century, actual power was held by military aristocrats known as shōgun and feudal lords called daimyō, enforced by warrior nobility named samurai.

Japan ranked seventh in the world in tonnage of fish caught and captured 3,167,610 metric tons of fish in 2016, down from an annual average of 4,000,000 tons over the previous decade. As the central coordinating body for the Prefectural Police Departments, the National Police Agency is administered by the National Public Safety Commission. The deployment of troops to Iraq and basswin Afghanistan marked the first overseas use of Japan’s military since World War II. The country’s military, the Japan Self-Defense Forces (JSDF), is restricted by Article 9 of the Japanese Constitution, which renounces Japan’s right to declare war or use military force in international disputes. Japan is widely considered to be a great power due to its economic power and political, cultural, and military influence. The broadly conservative Liberal Democratic Party has been the dominant party in the country since the 1950s, often called the 1955 System.