The zebrafish is a freshwater fish belonging to the minnow family (Cyprinidae) of the order Cypriniformes. Native to India and South Asia, it is a popular aquarium fish, frequently sold under the trade name zebra danio. It is also found in private ponds.
Developmental biology is the study of the process by which animals and plants grow and develop. Developmental biology also encompasses the biology of regeneration, asexual reproduction, metamorphosis, and the growth and differentiation of stem cells in the adult organism.
Hydra is a genus of small freshwater hydrozoans of the phylum Cnidaria. They are native to the temperate and tropical regions. The genus was named by Linnaeus in 1758 after the Hydra, which was the many-headed beast of myth defeated by Heracles, as when the animal had a part severed, it would regenerate much like the mythical hydra’s heads. Biologists are especially interested in Hydra because of their regenerative ability; they do not appear to die of old age, or to age at all.
The flatworms, flat worms, Platyhelminthes, or platyhelminths are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates. Unlike other bilaterians, they are acoelomates, and have no specialised circulatory and respiratory organs, which restricts them to having flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion. The digestive cavity has only one opening for both ingestion and egestion ; as a result, the food cannot be processed continuously.
The Sipuncula or Sipunculida is a class containing about 162 species of unsegmented marine annelid worms. The name Sipuncula is from the genus name Sipunculus, and comes from the Latin siphunculus meaning a "small tube".
Hemichordata is a phylum which consists of triploblastic, enterocoelomate, 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.
Any worm that lives in a marine environment is considered a water worm. Marine worms are found in several different phyla, including the Platyhelminthes, Nematoda, Annelida, Chaetognatha, Hemichordata, and Phoronida. For a list of marine animals that have been called "sea worms", see sea worm.
Caenorhabditis elegans is a free-living transparent nematode about 1 mm in length that lives in temperate soil environments. It is the type species of its genus. The name is a blend of the Greek caeno- (recent), rhabditis (rod-like) and Latin elegans (elegant). In 1900, Maupas initially named it Rhabditides elegans. Osche placed it in the subgenus Caenorhabditis in 1952, and in 1955, Dougherty raised Caenorhabditis to the status of genus.
Planarians (triclads) are free-living flatworms of the class Turbellaria., order Tricladida, which includes hundreds of species, found in freshwater, marine, and terrestrial habitats. Planarians are characterized by a three-branched intestine, including a single anterior and two posterior branches. Their body is populated by adult stem cells called neoblasts, which planarians use for regenerating missing body parts. Many species are able to regenerate any missing organ, which has made planarians a popular model in research of regeneration and stem cell biology. The genome sequences of several species are available, as are tools for molecular biology analysis.
Regeneration in biology is the process of renewal, restoration, and tissue growth that makes genomes, cells, organisms, and ecosystems resilient to natural fluctuations or events that cause disturbance or damage. Every species is capable of regeneration, from bacteria to humans. Regeneration can either be complete where the new tissue is the same as the lost tissue, or incomplete after which the necrotic tissue becomes fibrosis.
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.
The Drosophilidae are a diverse, cosmopolitan family of flies, which includes species called fruit flies, although they are more accurately referred to as vinegar or pomace flies. Another distantly related family of flies, Tephritidae, are true fruit flies because they are frugivorous, and include apple maggot flies and many pests. The best known species of the Drosophilidae is Drosophila melanogaster, within the genus Drosophila, also called the "fruit fly." Drosophila melanogaster is used extensively for studies concerning genetics, development, physiology, ecology and behaviour. Many fundamental biological mechanisms were discovered first in D. melanogaster. The fruit fly is mostly composed of post-mitotic cells, has a very short lifespan, and shows gradual aging. As in other species, temperature influences the life history of the animal. Several genes have been identified that can be manipulated to extend the lifespan of these insects. Additionally, Drosophila subobscura, also within the genus Drosophila, has been reputed as a model organism for evolutionary-biological studies, along with D. sechellia for the evolution of host specialization on the toxic noni fruit and Scaptomyza flava for the evolution of herbivory and specialist on toxic mustard leaves.
Lumbriculus variegatus, also known as the blackworm or California blackworm, is a species of worm inhabiting North America and Europe. It lives in shallow-water marshes, ponds, and swamps, feeding on microorganisms and organic material. The maximum length of a specimen is 10 cm (4 in). Worms raised in laboratory environment are slightly shorter, with 4 to 6 cm long bodies. An adult individual has approximately 150 to 250 1.5 mm wide segments, each of which has the ability to regenerate into a new individual when separated from the rest of the animal. In most populations, this is the primary mode of reproduction, and mature individuals are exceedingly rare; in large areas mature individuals have never been found. The name blackworm is given to at least three distinct species of worm that are identical in appearance and were once considered a single species.
Body memory (BM) is a hypothesis that the body itself is capable of storing memories, as opposed to only the brain. While experiments have demonstrated the possibility of cellular memory there are currently no known means by which tissues other than the brain would be capable of storing memories.
Pseudoceros is a genus of the flatworms Platyhelminthes.
Mychonastes is a genus of green algae, specifically of the Chlorophyceae. It is the sole genus of the family Mychonastaceae.
Marine invertebrates are the invertebrates that live in marine habitats. Invertebrate is a blanket term that includes all animals apart from the vertebrate members of the chordate phylum. Invertebrates lack a vertebral column, and some have evolved a shell or a hard exoskeleton. As on land and in the air, marine invertebrates have a large variety of body plans, and have been categorised into over 30 phyla. They make up most of the macroscopic life in the oceans.
An earthworm is a soil-dwelling terrestrial invertebrate that belongs to the phylum Annelida. The term is the common name for the largest members of the class Oligochaeta. In classical systems, they were in the order of Opisthopora since the male pores opened posterior to the female pores, although the internal male segments are anterior to the female. Theoretical cladistic studies have placed them in the suborder Lumbricina of the order Haplotaxida, but this may change. Other slang names for earthworms include "dew-worm", "rainworm", "nightcrawler", and "angleworm". Larger terrestrial earthworms are also called megadriles as opposed to the microdriles in the semiaquatic families Tubificidae, Lumbricidae and Enchytraeidae. The megadriles are characterized by a distinct clitellum and a vascular system with true capillaries.
Hofsteniidae is a family of acoels. This family contains seven species in three genera.
Epimorphosis is defined as the regeneration of a specific part of an organism in a way that involves extensive cell proliferation of somatic stem cells, dedifferentiation, and reformation, as well as blastema formation. Epimorphosis can be considered a simple model for development, though it only occurs in tissues surrounding the site of injury rather than occurring system-wide. Epimorphosis restores the anatomy of the organism and the original polarity that existed before the destruction of the tissue and/or a structure of the organism. Epimorphosis regeneration can be observed in both vertebrates and invertebrates such as the common examples: salamanders, annelids, and planarians.
