Acanthocephala is a phylum of parasitic worms known as acanthocephalans, thorny-headed worms, or spiny-headed worms, characterized by the presence of an eversible proboscis, armed with spines, which it uses to pierce and hold the gut wall of its host. Acanthocephalans have complex life cycles, involving at least two hosts, which may include invertebrates, fish, amphibians, birds, and mammals. About 1420 species have been described.
The rotifers, commonly called wheel animals or wheel animalcules, make up a phylum of microscopic and near-microscopic pseudocoelomate animals.
Bdelloidea is a class of rotifers found in freshwater habitats all over the world. There are over 450 described species of bdelloid rotifers, distinguished from each other mainly on the basis of morphology. The main characteristics that distinguish bdelloids from related groups of rotifers are exclusively parthenogenetic reproduction and the ability to survive in dry, harsh environments by entering a state of desiccation-induced dormancy (anhydrobiosis) at any life stage. They are often referred to as "ancient asexuals" due to their unique asexual history that spans back to over 25 million years ago through fossil evidence. Bdelloid rotifers are microscopic organisms, typically between 150 and 700 µm in length. Most are slightly too small to be seen with the naked eye, but appear as tiny white dots through even a weak hand lens, especially in bright light. In June 2021, biologists reported the restoration of bdelloid rotifers after being frozen for 24,000 years in the Siberian permafrost.
Monogononta is a class of rotifers, found mostly in freshwater but also in soil and marine environments. They include both free-swimming and sessile forms. Monogononts generally have a reduced corona, and each individual has a single gonad, which gives the group its name. Males are generally smaller than females, and are produced only during certain times of the year, with females otherwise reproducing through parthenogenesis.
Moray eels, or Muraenidae, are a family of eels whose members are found worldwide. There are approximately 200 species in 15 genera which are almost exclusively marine, but several species are regularly seen in brackish water, and a few are found in fresh water.
The bluegill, sometimes referred to as "bream", "brim", "sunny", or "copper nose" as is common in Texas, is a species of North American freshwater fish, native to and commonly found in streams, rivers, lakes, ponds and wetlands east of the Rocky Mountains. It is the type species of the genus Lepomis, from the family Centrarchidae in the order Perciformes.
The mata mata, mata-mata, or matamata is a freshwater turtle species found in South America, primarily in the Amazon and Orinoco basins. It is one of two extant species in the genus Chelus, the other being Chelus orinocensis.
Hydrophilidae, also known colloquially as water scavenger beetles, is a family of beetles. Aquatic hydrophilids are notable for their long maxillary palps, which are longer than their antennae. Several of the former subfamilies of Hydrophilidae have recently been removed and elevated to family rank; Epimetopidae, Georissidae, Helophoridae, Hydrochidae, and Spercheidae. While the majority of hydrophilids are aquatic, around a third of described species are terrestrial, mostly belonging to the subfamily Sphaeridiinae.
Snow algae are a group of freshwater micro-algae which grow in the alpine and polar regions of the earth. These algae have been observed to come in a variety of colors associated with both the individual species, stage of life or topography/geography. This variation is associated with both albedo differences of the snowy habitat and the presence of micro-invertebrates. Snow algae play a critical role in the trophic organization as primary producers who in turn are consumed primarily by tardigrades and rotifers. Snow algae have also been found to travel great distances being carried by winds.
Rhizodus is an extinct genus of basal, finned tetrapodomorphs. It belonged to Rhizodontida, one of the earliest-diverging tetrapodomorph clades. Two valid species have been described, both of which lived during the Early Carboniferous epoch. The type species R. hibberti is known from the Viséan stage of the United Kingdom, whereas the species R. serpukhovensis is from the Serpukhovian of Russia. Some fossils referred to the genus Rhizodus have also been found in North America.
Brachionus is a genus of planktonic rotifers occurring in freshwater, alkaline and brackish water.
The Ezo salamander, also known as the Hokkaido salamander, Noboribetsu salamander, or Ezo Sanshouo in Japanese is a species of salamander in the family Hynobiidae. Prior to 1923 the species was also classified by the binomial scientific name Satobius retardatus. H. retardatus is endemic to Japan's northernmost prefecture, the island of Hokkaido. The species is a pond-type salamander, and its natural habitats are temperate forests, temperate shrubland, swamps, freshwater marshes, intermittent freshwater marshes, freshwater springs, irrigated land, canals, and ditches.
Brachionus plicatilis is a euryhaline rotifer in the family Brachionidae, and is possibly the only commercially important rotifer, being raised in the aquaculture industry as food for fish larvae. It has a broad distribution in salt lakes around the world and has become a model system for studies in ecology and evolution.
Gnathifera is a clade of generally small spiralians characterized by complex jaws made of chitin. It comprises the phyla Gnathostomulida, Rotifera, Micrognathozoa, and Chaetognatha. It may also include the Cycliophora.
Brachionus calyciflorus is a planktonic rotifer species occurring in freshwater. It is commonly used as a model organism in toxicology, ecology and evolutionary biology.
Its advantages include the small size and short generation time.
Keratella cochlearis is a rotifer. The planktonic animal occurs worldwide in freshwater and marine habitats.
Halteria, sometimes referred to as the jumping oligotrich, is a genus of common planktonic ciliates that are found in many freshwater environments. Halteria are easy to locate due to their abundance and distinctive behaviour with observations of Halteria potentially dating back to the 17th century and the discovery of microorganisms. Over time more has been established about their morphology and behavior, which has led to many changes in terms of classification.
Asplanchna is a genus of rotifers belonging to the family Asplanchnidae.
Brachionidae is a family of rotifers belonging to the order Ploima. Species are found in freshwater and marine habitats.
Caridina typus, also known as the Australian Amano Shrimp, is a species of amphidromous atyid shrimp. It was first described by H. Milne-Edwards in 1837. It has a broad distribution in tropical freshwater habitats in the Indo-West Pacific region, with its western range extending to eastern Africa and its eastern range extending to Polynesia. It is commonly found in rivers and streams in coastal areas or on islands. C. typus is known to play a role in sediment distribution and shredding leaf litter, manipulating the environment using their pereiopods and setaceous chelae. The species is also an important component of the food web, both as scavengers and as prey items, and is considered a keystone species for the stream ecosystems it inhabits. According to Choy and Marshall, the species can be characterized by a "short, dorsally unarmed rostrum, the presence of epipods on the first four pairs of pereiopods, and the presence of an appendix interna on the endopod of the first pleopod of both sexes." It can be kept in captivity by aquarists as pets.
