''Urechis unicinctus'', known as the fat innkeeper worm or penis fish, is a species of marine spoon worm in

East Asia East Asia is the eastern region of Asia, which is defined in both geographical and ethno-cultural terms. The modern states of East Asia include China, Japan, Mongolia, North Korea, South Korea, and Taiwan. China, North Korea, South Korea and ...

. It is found in

Bohai Gulf The Bohai Sea () is a marginal sea approximately in area on the east coast of Mainland China. It is the northwestern and innermost extension of the Yellow Sea, to which it connects to the east via the Bohai Strait. It has a mean depth of a ...

of China and off the Korean and

Hokkaido is Japan's second largest island and comprises the largest and northernmost prefecture, making up its own region. The Tsugaru Strait separates Hokkaidō from Honshu; the two islands are connected by the undersea railway Seikan Tunnel. The la ...

coasts. It is not to be confused with a closely related species, ''

Urechis caupo ''Urechis caupo'' is a species of spoon worm in the family Urechidae, commonly known as the innkeeper echiuran, the fat innkeeper worm (because the tunnels often contain other animals), the innkeeper worm, or the penis fish. It is found in shal ...

'', 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.

Ecology

This spoonworm is a

detritivore Detritivores (also known as detrivores, detritophages, detritus feeders, or detritus eaters) are heterotrophs that obtain nutrients by consuming detritus (decomposing plant and animal parts as well as feces). There are many kinds of invertebrates, ...

, feeding on

detritus In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts commun ...

and lives and burrows in sand and mud like other ''Urechis'' species. It creates a U-shaped burrow in the soft sediment of the seabed. A ring of glands at the front of the

proboscis A proboscis () is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular mouthparts used for feeding and sucking. In vertebrates, a proboscis is an elong ...

secrete

mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It is ...

which sticks to the burrow wall. The worm continues to exude mucus as it moves backwards in the burrow thus creating a mucus net. The worm draws water through its burrow by peristaltic contractions of its body and food particles adhere to the net. When enough food is gathered, the worm moves forward in its burrow and swallows the net and entangled food. This process is repeated, and in an area with plenty of detritus, may be completed in only a few minutes. Large numbers have been known to become stranded on beaches in Japan, but further studies must be dedicated as to why. The original theory was that it was beached solely due to sea storms, but scientists also theorize that they swim at night to reproduce, which would raise the chances of beachings.

Uses

In Korea, they are eaten as food, often raw with salt and

sesame oil Sesame oil is an edible vegetable oil derived from sesame seeds. The oil is one of the earliest-known crop-based oils. Worldwide mass modern production is limited due to the inefficient manual harvesting process required to extract the oil. O ...

gochujang ''Gochujang'' (, from Korean: , ) or red chili paste * is a savory, sweet, and spicy fermented condiment popular in Korean cooking. It is made from gochu-garu (chili powder), glutinous rice, ''meju'' (fermented soybean) powder, ''yeotgireum'' ...

. They are distributed in Korea,

, and the Pacific coast. In

Chinese cuisine Chinese cuisine encompasses the numerous cuisines originating from China, as well as overseas cuisines created by the Chinese diaspora. Because of the Chinese diaspora and historical power of the country, Chinese cuisine has influenced many ot ...

, the worm is

stir-fried Stir frying () is a cooking technique in which ingredients are fried in a small amount of very hot oil while being stirred or tossed in a wok. The technique originated in China and in recent centuries has spread into other parts of Asia and th ...

with vegetables, or dried and powdered to be used as an

umami Umami ( from ja, 旨味 ), or savoriness, is one of the five basic tastes. It has been described as savory and is characteristic of broths and cooked meats. People taste umami through taste receptors that typically respond to glutamates and ...

enhancer. It is also used as

fishing bait Fishing bait is any substance used to attract and catch fish, e.g. on a fishing hook. Bait items are both selected from and placed within the environment to achieve enhanced prey capture success. Traditionally, fishing baits are natural fish food ...

for fish such as

flounder Flounders are a group of flatfish species. They are demersal fish, found at the bottom of oceans around the world; some species will also enter estuaries. Taxonomy The name "flounder" is used for several only distantly related species, thou ...

and

sea bream The Sparidae are a family of fish in the order Perciformes, commonly called sea breams and porgies. The sheepshead, scup, and red seabream are species in this family. Most sparids are deep-bodied compressed fish with a small mouth separated by a ...

. File:Gaebul.jpg, ''Urechis unicinctus'' () sold at a fish market at Busan, South Korea. File:Korean sea worm.jpg, ''Urechis unicinctus'' served as '' hoe'' in a restaurant in South Korea.

References

External links

5 Korean foods for adventurous eaters
Chincha.co.uk {{Taxonbar, from=Q716898 Echiurans Korean seafood Shandong cuisine