Polychaeta is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes. Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. More than 10,000 species are described in this class. Common representatives include the lugworm and the sandworm or clam worm Alitta.
The genus Glycera is a group of polychaetes commonly known as bloodworms. They are typically found on the bottom of shallow marine waters, and some species can grow up to 35 cm (14 in) in length.
External fertilization is a mode of reproduction in which a male organism's sperm fertilizes a female organism's egg outside of the female's body. It is contrasted with internal fertilization, in which sperm are introduced via insemination and then combine with an egg inside the body of a female organism.
The Clitellata are a class of annelid worms, characterized by having a clitellum – the 'collar' that forms a reproductive cocoon during part of their life cycles. The clitellates comprise around 8,000 species. Unlike the class of Polychaeta, they do not have parapodia and their heads are less developed.
Epitoky is a process that occurs in many species of polychaete marine worms wherein a sexually immature worm is modified or transformed into a sexually mature worm. Epitokes are pelagic morphs capable of sexual reproduction. Unlike the immature form, which is typically benthic, epitokes are specialized for swimming as well as reproducing. The primary benefit to epitoky is increased chances of finding other members of the same species for reproduction.
Nereididae are a family of polychaete worms. It contains about 500 – mostly marine – species grouped into 42 genera. They may be commonly called ragworms or clam worms.
Eunicidae is a family of marine polychaetes. The family comprises marine annelids distributed in diverse benthic habitats across Oceania, Europe, South America, North America, Asia and Africa. The Eunicid anatomy typically consists of a pair of appendages near the mouth (mandibles) and complex sets of muscular structures on the head (maxillae) in an eversible pharynx. One of the most conspicuous of the eunicids is the giant, dark-purple, iridescent "Bobbit worm", a bristle worm found at low tide under boulders on southern Australian shores. Its robust, muscular body can be as long as 2 m. Eunicidae jaws are known from as far back as Ordovician sediments. Cultural tradition surrounds Palola worm reproductive cycles in the South Pacific Islands. Eunicidae are economically valuable as bait in both recreational and commercial fishing. Commercial bait-farming of Eunicidae can have adverse ecological impacts. Bait-farming can deplete worm and associated fauna population numbers, damage local intertidal environments and introduce alien species to local aquatic ecosystems.
Alitta virens is an annelid worm that burrows in wet sand and mud. They construct burrows of different shapes They range from being very complex to very simple. Long term burrows are held together by mucus. Their burrows are not connected to each other; they are generally solitary creatures. The spacing between the burrows depends on how readily they can propagate water signals.
Spirobranchus giganteus, commonly known as the Christmas tree worm, is a tube-building polychaete worm belonging to the family Serpulidae. The S. giganteus lives in coral reefs in the Indo-Pacific region to the Caribbean.
Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, to spawn refers to the process of freely releasing eggs and sperm into a body of water ; the physical act is known as spawning. The vast majority of aquatic and amphibious animals reproduce through spawning. These include the following groups:
Sabellastarte spectabilis is a species of benthic marine polychaete worm in the Sabellidae family. It is commonly known as the feather duster worm, feather duster or fan worm. It is native to tropical waters of the Indo-Pacific but has spread to other parts of the world. It is popular in aquariums because of its distinctive appearance and its ability to remove organic particles and improve water quality.
Phyllodocida is an order of polychaete worms in the subclass Aciculata. These worms are mostly marine, though some are found in brackish water. Most are active benthic creatures, moving over the surface or burrowing in sediments, or living in cracks and crevices in bedrock. A few construct tubes in which they live and some are pelagic, swimming through the water column. There are estimated to be more than 4,600 accepted species in the order.
Platynereis dumerilii is a species of annelid polychaete worm. It was originally placed into the genus Nereis and later reassigned to the genus Platynereis. Platynereis dumerilii lives in coastal marine waters from temperate to tropical zones. It can be found in a wide range from the Azores, the Mediterranean, in the North Sea, the English Channel, and the Atlantic down to the Cape of Good Hope, in the Black Sea, the Red Sea, the Persian Gulf, the Sea of Japan, the Pacific, and the Kerguelen Islands. Platynereis dumerilii is today an important lab animal, it is considered a living fossil, and it is used in many phylogenetic studies as a model organism.
Hediste diversicolor, commonly known as a ragworm, is a polychaete worm in the family Nereididae. It lives in a burrow in the sand or mud of beaches and estuaries in intertidal zones in the north Atlantic. This species is used in research, but its classification is in dispute; in the literature, it is often classified as Nereis diversicolor. Its specific name "diversicolor" refers to the fact that its colour changes from brown to green as the breeding season approaches.
The annelids, also known as the segmented worms, comprise a large phylum called Annelida. It contains over 22,000 extant species, including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecologies – some in marine environments as distinct as tidal zones and hydrothermal vents, others in fresh water, and yet others in moist terrestrial environments.
Eulagisca gigantea is a species of scale worm. This species is specifically found in the deep-sea in cold waters like the Antarctic Ocean. The scale worms are named for the elytra on their surface that look like scales.
Syllis prolifera is a species of polychaete worm in the family Syllidae. It has a cosmopolitan distribution. It was first described in 1852 by the Russian/German zoologist August David Krohn who gave it the name Syllis prolifera.
Neanthes arenaceodentata is a species of marine polychaete worm in the family Nereididae. It occurs in shallow waters in the tropical Atlantic and Pacific Oceans. It has been used in the laboratory in testing the toxicity of marine sediments.
Pectinereis is a genus of nereid worm that contains only the species Pectinereis strickrotti. The genus name is a combination of the Latin words pectinis (comb) and Nereis. The species is named for Bruce Strickrott, lead pilot of the deep-submergence vehicle Alvin. Molecular phylogenetic analysis suggests that Pectinereis strickrotti is most closely related to Alitta, Nectoneanthes, and Nereis.
Platynereis bicanaliculata is a species of marine polychaete worm in the family Nereididae.
