| Derocheilocarididae | |
|---|---|
 | |
| Ctenocheilocaris galvarini | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Superclass: | Oligostraca |
| Subclass: | Mystacocarida Pennak & Zinn, 1943 |
| Order: | Mystacocaridida Pennak & Zinn, 1943 |
| Family: | Derocheilocarididae Pennak & Zinn, 1943 |
| Genera | |
Derocheilocarididae is a family of marinecrustaceans that form part of themeiobenthos. It is the only family in themonotypic orderMystacocaridida, and the monotypic subclassMystacocarida. Thesemystacocarids are less than 1 mm (0.04 in) long, and live interstitially in theintertidal zones of sandy beaches.
The taxonomy of the mystacocarids is extremely conservative, since all mystacocarids look superficially alike. As of December 2022[update], the 13 describedspecies are divided between twogenera,Derocheilocaris (eight species) andCtenocheilocaris (five species).[1][2] The first mystacocarids to be found were discovered on a beach in southernNew England in 1939.[3]
Mystacocarids occur along the coasts of South and North America, southern Africa, and the western Mediterranean.[4] 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.[2]
Mystacocarids are tiny pigmentless crustaceans, less than 1 mm (0.039 in) long, that live in the spaces between sand grains onintertidal beaches.[3][5] They have a cylindrical body, with fivethoracic and fiveabdominal segments.[6]
The appendages of the head—two pairs of longantennae, a pair of limb-likemandibles and two pairs ofmaxillae—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 alabrum 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 intomaxillipeds, 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.[7] 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, atelson and a pair of large, pincer-likefurca which on the ventral surface bears two sets of combs withsetae. Because of their small size, there is no circulatory or respiratory system.[8][9][10] A nauplius eye is completely absent.[11] After mating, mystacocarids lay tiny eggs which hatch into anauplius ormetanauplius larva.[4] Like the adults, the larvae are benthic.[12][13]