Malacostraca

(redirected from malacostracans)
Also found in: Dictionary, Thesaurus, Encyclopedia.

Malacostraca

the crustacean group containing crabs, lobsters, shrimps, crayfish, etc. See also CARIDOID FACIES.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
Mentioned in ?
References in periodicals archive ?
The complete sequence of the mitochondrial genome of the crustacean Penaeus monodon: are malacostracan crustaceans more closely related to insects than to branchiopods?
Because the brain anatomy of branchiopods is much simpler than that of malacostracans, they have been regarded as the more likely ancestors of the arthropod lineage that would give rise to insects.
However, the research, published in the journal Nature, notes that the shape of the fossilised brain matches that of modern malacostracans.
Current state of freshwater malacostracans of Chile.
It might be argued that the absence of RPCH (as a circulating neurohormone) would be expected since chromatophores are present only in malacostracans; however, immunocytochemical studies (Mangerich et al., 1986; Nussbaum and Dircksen, 1995) using the same antiserum that recognizes the N-terminal tetrapeptide sequence common to many AKHs (Schooneveld and Veenstra, 1985) have shown that RPCH-immunoreactive interneurons are very widely distributed in the brain, thoracic and stomatogastric ganglia, and ventral nerve cord in malacostracans.
Burnett (1984) postulated that the muscular DAA is a vestigial remnant of the tubular heart found in more primitive malacostracans, such as stomatopods.
However, some cases of non-functional hermaphroditism in males of gonochoristic species were also described in malacostracans (Charniaux-Cotton and Payen, 1985).
As in most other malacostracans, the largest part of the germ band is formed by stem cells in the posterior growth zone, the ectoteloblasts.
4B); and cirripeds, branchiopods, and malacostracans represent a more advanced stage, with the triads restricted to the periphery of the myofibrils (Fig.