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.
Ecdysozoa is a group of protostome animals, including Arthropoda, Nematoda, and several smaller phyla. The grouping of these animal phyla into a single clade was first proposed by Eernisse et al. (1992) based on a phylogenetic analysis of 141 morphological characters of ultrastructural and embryological phenotypes. This clade, that is, a group consisting of a common ancestor and all its descendants, was formally named by Aguinaldo et al. in 1997, based mainly on phylogenetic trees constructed using 18S ribosomal RNA genes.
Panarthropoda is a proposed animal clade containing the extant phyla Arthropoda, Tardigrada and Onychophora. Panarthropods also include extinct marine legged worms known as lobopodians ("Lobopodia"), a paraphyletic group where the last common ancestor and basal members (stem-group) of each extant panarthropod phylum are thought to have risen. However the term "Lobopodia" is sometimes expanded to include tardigrades and onychophorans as well.
Cycloneuralia is a proposed clade of ecdysozoan animals including the Scalidophora, the Nematoida, and the extinct Palaeoscolecid. It may be paraphyletic, or may be a sister group to Panarthropoda. Or perhaps Panarthropoda is paraphyletic with respect to Cycloneuralia. The group has also been considered a single phylum, sometimes given the old name Nemathelminthes. The uniting character is the nervous system organization with a circumpharyngeal brain and somata–neuropil–somata pattern. The name derives from the position of the brain around the pharynx.
Tong Dizhou was a Chinese embryologist known for his contributions to the field of cloning. He was a vice president of Chinese Academy of Science.
Scalidophora is a group of marine pseudocoelomate ecdysozoans that was proposed on morphological grounds to unite three phyla: the Kinorhyncha, the Priapulida and the Loricifera. The three phyla have four characters in common — chitinous cuticle that is moulted, rings of scalids on the introvert, flosculi, and two rings of introvert retracts. The introvert and abdomen are separated by a distinct neck region in all groups, but in adult macroscopic priapulids it becomes rudimentary in Priapulus and is completely absent in Halicryptus. However, the monophyly of the Scalidophora was not supported by two molecular studies, where the position of the Loricifera was uncertain or as sister to the Panarthropoda. Both studies supported a reduced Scalidophora comprising the Kinorhyncha and Priapulida as sister phyla. Their closest relatives are the Panarthropoda, Nematoda and Nematomorpha.
BrainMaps is an NIH-funded interactive zoomable high-resolution digital brain atlas and virtual microscope that is based on more than 140 million megapixels of scanned images of serial sections of both primate and non-primate brains and that is integrated with a high-speed database for querying and retrieving data about brain structure and function over the internet.
The subphylum Mandibulata constitutes one of the major subdivisions of the phylum Arthropoda, alongside Chelicerata. Mandibulates include the crustaceans, myriapods, and all true insects. The name "Mandibulata" refers to the mandibles, a modified pair of limbs used in food processing, the presence of which are characteristic of most members of the group.
Smith's dwarf chameleon, also known as the Elandsberg dwarf chameleon, is a species of lizard in the family Chamaeleonidae endemic to Fynbos in South Africa's Eastern Cape. As in several species of chameleons in the genus Bradypodion, the Smith's dwarf chameleon can use its color-changing ability to actively camouflage itself depending on the vision of the specific predator species by which it is being threatened.
Lymphocryptovirus is a genus of viruses in the order Herpesvirales, in the family Herpesviridae, in the subfamily Gammaherpesvirinae. This genus includes the human-infecting Human gammaherpesvirus 4, as well as viruses that infect both Old World monkeys and New World monkeys. Other names for the Lymphocryptovirus genus include Lymphocryptoviridae and gamma-1 herpesviruses. There are nine species in this genus. Diseases associated with this genus include: mononucleosis, Burkitt's lymphoma, and nasopharyngeal carcinoma.
Protostomia is the clade of animals once thought to be characterized by the formation of the organism's mouth before its anus during embryonic development. This nature has since been discovered to be extremely variable among Protostomia's members, although the reverse is typically true of its sister clade, Deuterostomia. Well-known examples of protostomes are arthropods, molluscs, annelids, flatworms and nematodes. They are also called schizocoelomates since schizocoely typically occurs in them.
Eurybacteria is a taxon created by Cavalier-Smith, which includes several groups of Gram-negative bacteria. In this model, it is the ancestor of gram positive bacteria. Their endospores are characterized by producing and presenting external flagella or mobility by bacterial displacement.
Planulozoa is a clade of animals that includes the superphyla Cnidaria and the Bilateria. The designation Planulozoa may be considered a synonym to ParaHoxozoa, which also contains Placozoa. Within Planulozoa, the Placozoa may be a sister of Cnidaria to the exclusion of Bilateria. The clade excludes basal animals such as the Ctenophora, and Porifera (sponges). Although this clade was sometimes used to specify a clade of Cnidaria and Bilateria to the exclusion of Placozoa, this is no longer favoured due to recent data indicating a sister group relationship between Cnidaria and Placozoa, another study still supports Placozoa as sister to Cnidaria+Bilateria.
The Spiralia are a morphologically diverse clade of protostome animals, including within their number the molluscs, annelids, platyhelminths and other taxa. The term Spiralia is applied to those phyla that exhibit canonical spiral cleavage, a pattern of early development found in most members of the Lophotrochozoa.
Rabdiophrys is a genus of nucleariid. However, Chao and Cavalier-Smith argue that Rabdiophrys is a rhizarian. It has 19 species, including the species Rabdiophrys anulifera.
The Articulata is a proposed higher taxon of animals with segmented bodies, consisting of Annelida and Panarthropoda. This theory states that these groups are descended from a common segmented ancestor. The Articulata hypothesis is an alternative to the hypothesis that ecdysis is a primitive characteristic – this would place Panarthropoda in the group Ecdysozoa.
Direct development is a concept in biology. It refers to forms of growth to adulthood that do not involve metamorphosis. An animal undergoes direct development if the immature organism resembles a small adult rather than having a distinct larval form. A frog that hatches out of its egg as a small frog undergoes direct development. A frog that hatches out of its egg as a tadpole does not.
Choanozoa is a clade of opisthokont eukaryotes consisting of the choanoflagellates (Choanoflagellatea) and the animals. The sister-group relationship between the choanoflagellates and animals has important implications for the origin of the animals. The clade was identified in 2015 by Graham Budd and Sören Jensen, who used the name Apoikozoa. The 2018 revision of the classification first proposed by the International Society of Protistologists in 2012 recommends the use of the name Choanozoa.
Shankouclava is an extinct genus of tunicates. It represents the oldest candidate member of this group, dating to 518 million years ago. It has been found in the Lower Cambrian Maotianshan Shale at Shankou village, Anning, near Kunming. Each of the eight specimens found and used for description were isolated, suggesting that the genus was solitary and not colonial.
