Derocheilocarididae is a family of

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

s that form part of the

meiobenthos Meiobenthos, also called meiofauna, are small benthic invertebrates that live in both marine and fresh water environments. The term ''meiofauna'' loosely defines a group of organisms by their size, larger than microfauna but smaller than macrofau ...

. It is the only family in the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

order Mystacocaridida, and the monotypic subclass Mystacocarida. These mystacocarids are less than long, and live interstitially in the

intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species of ...

s of sandy beaches.

Taxonomy

The taxonomy of the mystacocarids is extremely conservative, since all mystacocarids look superficially alike. , the 13 described

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

are divided between two

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomencl ...

, ''Derocheilocaris'' (eight species) and ''Ctenocheilocharis'' (five species). The first mystacocarids to be found were discovered on a beach in southern

New England New England is a region comprising six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York to the west and by the Canadian provinces ...

in 1939.

Distribution

Mystacocarids occur along the coasts of South and North America, southern Africa, and the western Mediterranean. The lack of records from other parts of the world is "almost certainly" due to a lack of appropriate sampling, rather than a true absence.

Description

Mystacocarids are tiny crustaceans, less than long, that live in the spaces between sand grains on

intertidal The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species of ...

beaches. They have a cylindrical body, with five

thoracic The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the crea ...

and five

abdominal The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...

segments. Four pairs of small thoracic appendages are seen. The head is relatively large and divided into two by a stricture, so that the latter part gives the appearance of being a part of the thorax. This region bears a pair of

maxilliped An appendage (or outgrowth) is an external body part, or natural prolongation, that protrudes from an organism's body. In arthropods, an appendage refers to any of the homologous body parts that may extend from a body segment, including anten ...

s, and the head also has two pairs of

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...

e, a pair of limb-like

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...

s, and two pairs of long antennae. The appendages on the head are much longer than those on the thorax, and have a number of fine hairs that the animal uses to strain detritus from the water to feed on. They have a single naupliar eye. After mating, mystacocarids lay tiny eggs which hatch into a nauplius or

metanauplius Metanauplius is an early larval stage of some crustaceans such as krill. It follows the nauplius stage. In sac-spawning krill, there is an intermediary phase called pseudometanauplius, a newly hatched form distinguished from older metanauplii by ...

larva.

References

{{Taxonbar, from=Q132685 Maxillopoda Arthropod subclasses