Bilateria is a large clade or infrakingdom of animals called bilaterians, characterized by bilateral symmetry during embryonic development. This means their body plans are laid around a longitudinal axis with a front and a rear end, as well as a left–right–symmetrical belly (ventral) and back (dorsal) surface. Nearly all bilaterians maintain a bilaterally symmetrical body as adults; the most notable exception is the echinoderms, which extend to pentaradial symmetry as adults, but are only bilaterally symmetrical as an embryo. Cephalization is also a characteristic feature among most bilaterians, where the special sense organs and central nerve ganglia become concentrated at the front/rostral end.
Vertebrate paleontology is the subfield of paleontology that seeks to discover, through the study of fossilized remains, the behavior, reproduction and appearance of extinct vertebrates. It also tries to connect, by using the evolutionary timeline, the animals of the past and their modern-day relatives.
Acoelomorpha is a subphylum of very simple and small soft-bodied animals with planula-like features which live in marine or brackish waters. They usually live between grains of sediment, swimming as plankton, or crawling on other organisms, such as algae and corals. With the exception of two acoel freshwater species, all known acoelomorphs are marine.
India is the world's 8th most biodiverse region with a 0.46 BioD score on diversity index, 102,718 species of fauna and 23.39% of the nation's geographical area under forest and tree cover in 2020. India encompasses a wide range of biomes: desert, high mountains, highlands, tropical and temperate forests, swamplands, plains, grasslands, areas surrounding rivers, as well as island archipelago. Officially, four out of the 36 Biodiversity Hotspots in the world are present in India: the Himalayas, the Western Ghats, the Indo-Burma and the Nicobar Islands. To these may be added the Sundarbans and the Terrai-Duar Savannah grasslands for their unique foliage and animal species. These hotspots have numerous endemic species. Nearly 5% of India's total area is formally classified under protected areas.
On 29 January 2010, the IUCN Red List of Threatened Species identified 5220 endangered species, subspecies and varieties, stocks and sub-populations.
Version 2014.2 of the IUCN Red List of Threatened Species identified 4574 Critically Endangered species, subspecies, varieties, stocks, and subpopulations.
The fauna of Canada consist of approximately 200 mammal species, over 460 native bird species, 43 amphibian species, 43 reptile species, and 1,200 fish species. The biology survey of Canada cites that there are approximately 55,000 species of insects, and 11,000 species of mites and spiders.
The fauna of the United States of America is all the animals living in the Continental United States and its surrounding seas and islands, the Hawaiian Archipelago, Alaska in the Arctic, and several island-territories in the Pacific and in the Caribbean. The U.S. has many endemic species found nowhere else on Earth. With most of the North American continent, the U.S. lies in the Nearctic, Neotropic, and Oceanic faunistic realms, and shares a great deal of its flora and fauna with the rest of the American supercontinent.
The following outline is provided as an overview of and topical guide to zoology:
Ambulacraria, or Coelomopora, is a clade of invertebrate phyla that includes echinoderms and hemichordates; a member of this group is called an ambulacrarian. Phylogenetic analysis suggests the echinoderms and hemichordates separated around 533 million years ago. The Ambulacraria are part of the deuterostomes, a clade that also includes the many Chordata, and the few extinct species belonging to the Vetulicolia.
Pakistan's native fauna reflect its varied climatic zones. The northern Pakistan, which includes Khyber Pakhtunkhwa and Gilgit Baltistan, has portions of two biodiversity hotspots, Mountains of Central Asia and Himalayas.
Deuterostomes are bilaterian animals of the superphylum Deuterostomia, typically characterized by their anus forming before the mouth during embryonic development. Deuterostomia is further divided into four phyla: Chordata, Echinodermata, Hemichordata, and the extinct Vetulicolia known from Cambrian fossils. The extinct clade Cambroernida is thought to be a member of Deuterostomia.
On 12 March 2010, the IUCN Red List of Threatened Species identified 3829 near threatened species, subspecies and varieties, stocks and sub-populations.
The wildlife of the Philippines includes a significant number of endemic plant and animal species. The country's surrounding waters reportedly have the highest level of marine biodiversity in the world. The Philippines is one of the seventeen megadiverse countries and is a global biodiversity hotspot. In 2013, 700 of the country's 52,177 species were listed as threatened.
Reptiles arose about 320 million years ago during the Carboniferous period. Reptiles, in the traditional sense of the term, are defined as animals that have scales or scutes, lay land-based hard-shelled eggs, and possess ectothermic metabolisms. So defined, the group is paraphyletic, excluding endothermic animals like birds that are descended from early traditionally-defined reptiles. A definition in accordance with phylogenetic nomenclature, which rejects paraphyletic groups, includes birds while excluding mammals and their synapsid ancestors. So defined, Reptilia is identical to Sauropsida.
The common watersnake is a species of large, nonvenomous, common snake in the family Colubridae. The species is native to North America. It is frequently mistaken for the venomous cottonmouth.
Wyoming is home to 12 amphibian species and 22 species of reptiles.
Xenacoelomorpha is a small phylum of bilaterian invertebrate animals, consisting of two sister groups: xenoturbellids and acoelomorphs. This new phylum was named in February 2011 and suggested based on morphological synapomorphies, which was then confirmed by phylogenomic analyses of molecular data.
The fauna of Bangladesh includes about 1,600 species of vertebrate fauna and about 1,000 species of invertebrate fauna based on incomplete records. The vertebrate fauna consists of roughly 22 species of amphibians, 708 species of fish, 126 species of reptiles, 628 species of birds and 113 species of mammals. The invertebrate fauna includes about 30 species of aphids, 20 species of bees, 178 species of beetles, 135 species of flies, 400 species of spiders, 150 species of lepidopterans 52 species of decapods, 30 species of copepods, 2 species of starfish, and some species of sand dollars, sea cucumbers, and sea urchins.
