Hemichordata is a phylum which consists of triploblastic, eucoelomate, and bilaterally symmetrical marine deuterostome animals, generally considered the sister group of the echinoderms. They appear in the Lower or Middle Cambrian and include two main classes: Enteropneusta, and Pterobranchia. A third class, Planctosphaeroidea, is known only from the larva of a single species, Planctosphaera pelagica. The class Graptolithina, formerly considered extinct, is now placed within the pterobranchs, represented by a single living genus Rhabdopleura.
Graptolites are a group of colonial animals, members of the subclass Graptolithina within the class Pterobranchia. These filter-feeding organisms are known chiefly from fossils found from the Middle Cambrian through the Lower Carboniferous (Mississippian). A possible early graptolite, Chaunograptus, is known from the Middle Cambrian. Recent analyses have favored the idea that the living pterobranch Rhabdopleura represents an extant graptolite which diverged from the rest of the group in the Cambrian.
Polistes is a cosmopolitan genus of paper wasps and the only genus in the tribe Polistini. Vernacular names for the genus include umbrella wasps, coined by Walter Ebeling in 1975 to distinguish it from other types of paper wasp, in reference to the form of their nests, and umbrella paper wasps. Polistes is the single largest genus within the family Vespidae, with over 200 recognized species. Their innate preferences for nest-building sites leads them to commonly build nests on human habitation, where they can be very unwelcome; although generally not aggressive, they can be provoked into defending their nests. All species are predatory, and they may consume large numbers of caterpillars, in which respect they are generally considered beneficial.
Balanoglossus is a genus of ocean-dwelling acorn worms. It has zoological importance because, being hemichordates, they are an "evolutionary link" between invertebrates and vertebrates. Balanoglossus specimens are deuterostomes, and resemble the sea squirts in that they possess branchial openings, or "gill slits". They have notochords and stomochords but no dorsal nerve cord.
The acorn worms or Enteropneusta are a hemichordate class of invertebrates consisting of one order of the same name. The closest non-hemichordate relatives of the Enteropneusta are the echinoderms. There are 111 known species of acorn worm in the world, the main species for research being Saccoglossus kowalevskii. Two families—Harrimaniidae and Ptychoderidae—separated at least 370 million years ago.
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. 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. Animals form a clade, meaning that they arose from a single common ancestor.
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.
Leeches are segmented parasitic or predatory worms that comprise the subclass Hirudinea within the phylum Annelida. They are closely related to the oligochaetes, which include the earthworm, and like them have soft, muscular segmented bodies that can lengthen and contract. Both groups are hermaphrodites and have a clitellum, but leeches typically differ from the oligochaetes in having suckers at both ends and ring markings that do not correspond with their internal segmentation. The body is muscular and relatively solid; the coelom, the spacious body cavity found in other annelids, is reduced to small channels.
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.
Phoronids are a small phylum of marine animals that filter-feed with a lophophore, and build upright tubes of chitin to support and protect their soft bodies. They live in most of the oceans and seas, including the Arctic Ocean but excluding the Antarctic Ocean, and between the intertidal zone and about 400 meters down. Most adult phoronids are 2 cm long and about 1.5 mm wide, although the largest are 50 cm long.
Saccoglossus is a genus of acorn worm. It is the largest genus in the Enteropneusta class, with 20 species.
Ptychoderidae is a family of acorn worms.
Meioglossus psammophilus is a species of acorn worm in the family Harrimaniidae, the only known species of the genus Meigolossus. It inhabits the Western Caribbean and Bermuda. The name of the species derives from two Greek words; psammon and philos which in translation means friend of the sands in reference to adult stage of species' lifestyle. The length of the species is 0.6 millimetres (0.024 in). It is able to reproduce asexually through paratomy.
Mesoglossus intermedius is a species of acorn worms in the family Harrimaniidae, which is endemic to Northern California.
Mesoglossus caraibicus is a species of acorn worm in the family Harrimaniidae, which can be found on Bahamas, Greater Antilles, Southern Caribbean, and Gulf of Mexico.
Cornelius Jan van der Horst was a Dutch biologist who worked mainly on marine biology and embryology in both the Netherlands and South Africa. As an undergraduate he studied botany and zoology at the University of Amsterdam where he was appointed assistant in the Botany Department under Professor Dr Hugo de Vries before moving on to assist Max Wilhelm Carl Weber at the University's Zoological Museum and in 1917 he became the principal assistant for general Zoology. In 1916 he published his thesis De motorische kernen en banen in de hersenen der visschen. Hare taxonomische waarde en neurobiotactische beteekenis. The research for this thesis was carried out at the Netherlands Central Institute for Brain Research under C. U. Ariëns Kappers. In 1925 Van der Horst was appointed Deputy Director of this Netherlands Central Institute for Brain Research and in 1928 he moved to South Africa where he took up a post as senior lecturer in zoology at the University of the Witwatersrand in Johannesburg. in 1932 he was promoted to professor in zoology at this University.
Stereobalanus is a genus of acorn worms belonging to the family Harrimaniidae.
Glossobalanus is a genus of worms belonging to the family Ptychoderidae.
Mesoglossus is a genus of worms belonging to the family Harrimaniidae.
Ritteria is a monotypic genus of worms belonging to the family Harrimaniidae. The only species is Ritteria ambigua.
