Derocheilocarididae is a family of marine

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s that form part of the

meiobenthos Meiobenthos, also called meiofauna, are small benthic invertebrates that live in marine or freshwater environments, or both. The term ''meiofauna'' loosely defines a group of organisms by their sizelarger than microfauna but smaller than macr ...

. 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 "unisp ...

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

intertidal zone The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various ...

s of sandy beaches.

Taxonomy

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

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

are divided between two

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

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

New England New England is a region consisting of 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 (state), New York to the west and by the ...

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 pigmentless crustaceans, less than long, that live in the spaces between sand grains on intertidal beaches. They have a cylindrical body, with five

thoracic The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of 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 ...

and five abdominal segments. The appendages of the head—two pairs of long antennae, a pair of limb-like mandibles and two pairs of maxillae—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. Also a labrum is present. The head is relatively large and divided into two by a stricture, so that the larger posterior part gives the appearance of being the thorax. The actual thorax has five pairs of thoracic limbs. The pair on the first segment has been modified into maxillipeds, which collaborates with the maxillae in the feeding process, but is not fused with the head. These three pairs of limbs looks similar, but the maxillipeds can be distinguished from the maxillae in the form of a vestigial exopod. The remaining four thoracic pairs of limbs has been reduced to small, unsegmented lobes, but the last pair is slightly modified in males. Their limbless abdomen ends in a supra-anal plate, a

telson The telson () is the hindmost division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment (biology), segment of the arthropod body, or an additional division that is not a true segm ...

and a pair of large, pincer-like furca which on the ventral surface bears two sets of combs with

setae In biology, setae (; seta ; ) are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Depending partly on their form and function, protostome setae may be called macrotrichia, chaetae ...

. Because of their small size, there is no circulatory or respiratory system. A nauplius eye is completely absent. After mating, mystacocarids lay tiny eggs which hatch into a nauplius or metanauplius larva. Like the adults, the larvae are benthic.

References

{{Taxonbar, from=Q132685 Maxillopoda Arthropod subclasses