| Ikeda taenioides | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Annelida |
| Class: | Polychaeta |
| Subclass: | Echiura |
| Order: | Echiuroidea |
| Family: | Ikedidae |
| Genus: | Ikeda |
| Species: | I. taenioides |
| Binomial name | |
| Ikeda taenioides | |
| Synonyms [1] | |
| |
Ikeda taenioides is a species of spoon worm in the family Ikedidae. It is native to the northern Pacific Ocean where it is found in the subtidal waters around Japan.
This spoon worm was first described by the Japanese zoologist I. Ikeda in 1904 as Thalassema taenioides, the type locality being Misaki, Sagami Bay, in Honshu, Japan. Examination of the musculature of the body wall led to the observation that the longitudinal muscle layer lay outside both the circular layer and the inner oblique layer, and as this was at odds with all other members of the subclass Echiura, it warranted the creation of a new order. However, examination of the original material by Teruaki Nishikawa in 2002, showed that the longitudinal muscle layer was in fact between the circular layer and the oblique layer, as in all other echurians, throwing the taxonomy of the species into doubt. Nishikawa advocates that the family Ikedidae be regarded as a junior synonym of Echiuridae. [2]
Ikeda taenioides is the largest spoon worm in the world, its proboscis being visible protruding from its burrow while the trunk remains hidden. [3] The trunk can be 40 cm (16 in) long and the proboscis 150 cm (60 in). [4]
Ikeda taenioides lives in soft sediment where it digs itself a burrow, often descending to 70 to 90 cm (28 to 35 in) below the sand surface. The proboscis is protruded through the burrow entrance to feed, and a number of these probosces were observed by researchers in 2011, some eight months after a tsunami had devastated the seabed habitat. [3] The tsunami had destroyed the seagrass beds, the heart urchins and the Venus clams in the community; the researchers thought the spoon worms had survived the turbulent conditions because of the depths of their burrows. [3]
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".
The Echiura, or spoon worms, are a small group of marine animals. Once treated as a separate phylum, they are now considered to belong to Annelida. Annelids typically have their bodies divided into segments, but echiurans have secondarily lost their segmentation. The majority of echiurans live in burrows in soft sediment in shallow water, but some live in rock crevices or under boulders, and there are also deep sea forms. More than 230 species have been described. Spoon worms are cylindrical, soft-bodied animals usually possessing a non-retractable proboscis which can be rolled into a scoop-shape to feed. In some species the proboscis is ribbon-like, longer than the trunk and may have a forked tip. Spoon worms vary in size from less than a centimetre in length to more than a metre.
Nemertea is a phylum of animals also known as ribbon worms or proboscis worms, consisting of 1300 known species. Most ribbon worms are very slim, usually only a few millimeters wide, although a few have relatively short but wide bodies. Many have patterns of yellow, orange, red and green coloration. The foregut, stomach and intestine run a little below the midline of the body, the anus is at the tip of the tail, and the mouth is under the front. A little above the gut is the rhynchocoel, a cavity which mostly runs above the midline and ends a little short of the rear of the body. All species have a proboscis which lies in the rhynchocoel when inactive but everts to emerge just above the mouth to capture the animal's prey with venom. A highly extensible muscle in the back of the rhynchocoel pulls the proboscis in when an attack ends. A few species with stubby bodies filter feed and have suckers at the front and back ends, with which they attach to a host.
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.
Oligochaeta is a subclass of animals in the phylum Annelida, which is made up of many types of aquatic and terrestrial worms, including all of the various earthworms. Specifically, oligochaetes comprise the terrestrial megadrile earthworms, and freshwater or semiterrestrial microdrile forms, including the tubificids, pot worms and ice worms (Enchytraeidae), blackworms (Lumbriculidae) and several interstitial marine worms.
A hydrostatic skeleton, or hydroskeleton, is a flexible skeleton supported by fluid pressure. Hydrostatic skeletons are common among simple invertebrate organisms. While more advanced organisms can be considered hydrostatic, they are sometimes referred to as hydrostatic for their possession of a hydrostatic organ instead of a hydrostatic skeleton. A hydrostatic organ and a hydrostatic skeleton may have the same capabilities, but they are not the same. Hydrostatic organs are more common in advanced organisms, while hydrostatic skeletons are more common in primitive organisms. As its name suggests, containing hydro meaning "water", being hydrostatic means that the skeleton or organ is fluid-filled.
A muscular hydrostat is a biological structure found in animals. It is used to manipulate items or to move its host about and consists mainly of muscles with no skeletal support. It performs its hydraulic movement without fluid in a separate compartment, as in a hydrostatic skeleton.
Anopla has long been used as name for a class of marine worms of the phylum Nemertea, characterized by the absence of stylets on the proboscis, the mouth being below or behind the brain, and by having separate openings for the mouth and proboscis. The other long used class of Nemertea are the Enopla. Although Anopla is a paraphyletic grouping, it is used in almost all scientific classifications. Anopla is divided into two orders: Palaeonemertea and Heteronemertea.
Urechis unicinctus, known as the fat innkeeper worm or penis fish, is a species of marine spoon worm in East Asia. It is found in Bohai Gulf of China and off the Korean and Hokkaido coasts. It is not to be confused with a closely related species, Urechis caupo, which occurs on the western coast of North America and shares common names. The body is about 10–30 cm long, cylindrical in shape and yellowish-brown in color. On the surface of the body there are many small papillae.
Sipunculus nudus is a cosmopolitan species of unsegmented marine worm of the phylum Sipuncula, also known as peanut worms.
Myoscolex is an early animal species known from the Cambrian Emu Bay Shale in South Australia. It was interpreted as an annelid and some supports that theory, while it was also considered as an arthropod close to Opabinia, through other studies questions that interpretation. Myoscolex is the earliest known example of phosphotized muscle tissue, and as to which shows distinct annulation.
Listriolobus pelodes is a species of marine spoon worm. It is found in shallow seas in the North East Pacific off the coast of California. It lives in a burrow in soft sediments.
The annelids, also known as the segmented worms, are a large phylum, with 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.
Saccoglossus bromophenolosus is a species of acorn worm occurring in the northwestern Atlantic Ocean and the northeastern Pacific Ocean. It grows to a length of about 20 cm (8 in) and lives in a burrow in soft sediment in the intertidal and subtidal zones. The scientific name refers to 2,4-dibromophenol, a secondary metabolite present in this worm.
Bonelliidae is a family of marine worms noted for being sexually dimorphic, with males being tiny in comparison with the females. They occupy burrows in the seabed in many parts of the world's oceans, often at great depths.
Urechis caupo is a species of spoon worm in the family Urechidae, commonly known as the innkeeper echiuran, the fat innkeeper worm, the innkeeper worm, or the penis fish. It is found in shallow water on the west coast of North America, between southern Oregon and Baja California, where it forms a U-shaped burrow in the sediment and feeds on plankton using a mucus net.
Ochetostoma erythrogrammon is a species of spoon worm in the family Thalassematidae. It is found in shallow water in the Atlantic Ocean, the Mediterranean Sea, and the Indian and Pacific Oceans, burrowing in soft sediment.
Echiurus echiurus is a species of spoon worm in the family Echiuridae. It is found in the North Atlantic Ocean and a subspecies is found in Alaska. It burrows into soft sediment and under boulders and stones in muddy places.
Ikedidae is a family of spoon worms in the suborder Bonelliida. It is a monotypic family, the only genus being Ikeda. These worms burrow into soft sediment on the seabed.
Maxmuelleria lankesteri is a species of spoon worm in the family Bonelliidae. It is found in the North Atlantic Ocean. It burrows into soft sediment on the seabed, mostly in deep water.