Urothoe marina
Encyclopedia
Urothoe marina is a species
of small marine amphipod
crustacean
s in the family
Urothoidae
. It is found on and burrowing in coarse sediments in shallow coastal waters off northwestern Europe.
. In the male, the lower antenna is as long as the body but in the female, it is only just longer than the upper one. The upper antenna has a short side branch. The stalked eyes are black. Those of the male are very large while the female has smaller, oval eyes. The thorax consists of eight somite
s each with its own appendage
s and some seta
e. The posterior pereiopods are wider than they are long and have feathery setae. The uropods are densely hairy and the short telson
has a single spine and a few setae.
, the English Channel
and the Atlantic Ocean
from the Shetland Isles southwards to the Bay of Biscay
. It is usually found in the neritic zone
and at depths of down to 200 metres (656.2 ft).
of this species is very limited.
), making use of its burrow as a refuge. It also found in association with members of the sea cucumber family, Synaptidae
.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of small marine amphipod
Amphipoda
Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. The name amphipoda means "different-footed", and refers to the different forms of appendages, unlike isopods, where all the legs are alike. Of the 7,000 species, 5,500 are classified...
crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Urothoidae
Urothoidae
Urothoidae is a family of small marine amphipod crustaceans. Members of the family are found worldwide and are mainly detrivores and interface grazers, though some are also facultative filter feeders.-Genera:*Carangolia J.L...
. It is found on and burrowing in coarse sediments in shallow coastal waters off northwestern Europe.
Description
U. marina is about 8 millimetre (0.31496062992126 in) long, crescent-shaped and a yellowish-white colour. It is laterally compressed and normally lies on one side. The head is fused with the thorax and bears two unequal sized antennaeAntenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
. In the male, the lower antenna is as long as the body but in the female, it is only just longer than the upper one. The upper antenna has a short side branch. The stalked eyes are black. Those of the male are very large while the female has smaller, oval eyes. The thorax consists of eight somite
Somite
A somite is a division of the body of an animal. In vertebrates this is mainly discernible in the embryo stage; in arthropods it is a characteristic of a hypothetical ancestor.- In vertebrates :...
s each with its own appendage
Appendage
In invertebrate biology, an appendage is an external body part, or natural prolongation, that protrudes from an organism's body . It is a general term that covers any of the homologous body parts that may extend from a body segment...
s and some seta
Seta
Seta is a biological term derived from the Latin word for "bristle". It refers to a number of different bristle- or hair-like structures on living organisms.-Animal setae:In zoology, most "setae" occur in invertebrates....
e. The posterior pereiopods are wider than they are long and have feathery setae. The uropods are densely hairy and the short telson
Telson
The telson is the last division of the body of a crustacean. It is not considered a true segment because it does not arise in the embryo from teloblast areas as do real segments. It never carries any appendages, but a forked "tail" called the caudal furca is often present. Together with the...
has a single spine and a few setae.
Distribution
U. marina occurs off the coasts of northwest Europe. Its range includes the North SeaNorth Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...
, the English Channel
English Channel
The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...
and the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
from the Shetland Isles southwards to the Bay of Biscay
Bay of Biscay
The Bay of Biscay is a gulf of the northeast Atlantic Ocean located south of the Celtic Sea. It lies along the western coast of France from Brest south to the Spanish border, and the northern coast of Spain west to Cape Ortegal, and is named in English after the province of Biscay, in the Spanish...
. It is usually found in the neritic zone
Neritic zone
The neritic zone, also called coastal waters, the coastal ocean or the sublittoral zone, is the part of the ocean extending from the low tide mark to the edge of the continental shelf, with a relatively shallow depth extending to about 200 meters...
and at depths of down to 200 metres (656.2 ft).
Reproduction
U. marina becomes sexually mature at about five months old and may live for a year. The sexes are distinct and breeding takes place between April and October. Fertilisation is internal and there are about fifteen eggs, with batches produced every fifteen days or so. The eggs are brooded rather than being liberated into the water column and the juveniles grow rapidly. Biological dispersalBiological dispersal
Biological dispersal refers to species movement away from an existing population or away from the parent organism. Through simply moving from one habitat patch to another, the dispersal of an individual has consequences not only for individual fitness, but also for population dynamics, population...
of this species is very limited.
Ecology
The back three legs of U. marina have flattened joints and are used for digging and it can quickly disappear into the substrate. It is often found in association with the sea potato (Echinocardium cordatumEchinocardium cordatum
Echinocardium cordatum, or the sea potato, is a sea urchin in the family Loveniidae. It is found in sub-tidal regions in temperate seas around the world and lives buried in the sandy sea floor.-Description:...
), making use of its burrow as a refuge. It also found in association with members of the sea cucumber family, Synaptidae
Synaptidae
Synaptidae is a family of sea cucumber that have no tube feet, tentacle ampullae, retractor muscles, respiratory trees, or cuvierian organs. They also lack radial canals of the water-vascular system, with only the circumoral ring present....
.