Comparative ultrastructure of the cuticle of some pelagic, nektobenthic and benthic malacostracan crustaceans

Abstract

The ultrastructure of malacostracan integument was examined and compared in 11 species collected primarily from the western Baltic Sea in 1989, of which eight species were studied for the first time (indicated below by an asterisk). We attempted to relate cuticle structure and thickness to swimming aptitude. The pelagic euphausiid Meganyctiphanes norvegia and the mysids Praunus flexuosus* and Neomysis integer* displayed a thin, little-mineralized, and thus light-weight cuticle. Laminae of the endocuticle were very thin (0.1/~m) relative to those of the exocuticle (1/~m). In contrast, laminae in the procuticles of the benthic amphipods Gammarus locusta, Caprella linearis*, Corophiurn volutator*, Orchestia garnrnarellus*, and the isopod Idotea baltica were evenly distributed, comparatively thick (1 to 2/~m), and more heavily mineralized. The nektobenthic amphipod Hyperia galba*, the cumacean Diastylis rathkei* and the decapod Crangon crangon* migrate between pelagic and benthic regions. Only near the hypodermis did these organisms exhibit the characteristically pelagic fine-layered endocuticle. A membranous layer was lacking in all species investigated. In contrast to the less-mineralized cuticles of the species analyzed here, a membranous layer appears to be restricted to crustaceans with heavily calcified shells. Ultrastructural results were substantiated by morphometric calculations, which indicated differences in thickness of the total cuticle relative to body volume. In the pelagic malacostracans, thickness of the cuticle did not increase with body volume over the size range investigated.

Changes in cuticle structure during growth in two terrestrial isopods (Crustacea: Isopoda: Oniscidea)

“…The conclusions were that the cuticle of marsupial mancae is structurally similar to adult cuticles and is already mineralized, but is much thinner. A similar trend of cuticle thickening with increasing body size has previously been demonstrated in benthic marine malacostracans, including a benthic isopod, whereas cuticle thickness was shown to remain constant during growth in pelagic species (Pütz and Buchholz, 1991;Waugh et al, 2009). Changes in the thickness of the integument during ontogenetic development may have a profound impact on woodlice biology.…”

Ultrastructure and cuticle formation of the carapace in the myodocopan ostracod exemplified by Euphilomedes japonica (Crustacea: Ostracoda)

“…Voss‐Foucart and Jeuniaux () compared the relative thickness of the membranous layer in the carapace of several decapods and found interrelations between the degree of mineralization and the thickness of this layer. According to this result, Pütz and Buchholz () proposed that the membranous layer is an additional layer only occurring in large calcified decapods. In podocopid ostracods, the membranous layer has been described in some species irrespective of the degree of mineralization.…”

“…In other calcified crustaceans, similar correlations between the cuticle ultrastructure and the lifestyle have been detected. Pütz and Buchholz () examined the cuticle ultrastructure in some pelagic, nektobenthic, and benthic malacostracans and they suggested that some cuticle features correlate with the modes of life. They claimed that the thinner procuticle of pelagic species gain strength from closely packed laminations of chitinous layers, whereas the benthic species possess a procuticle with fewer laminations of chitinous layers, providing more space for mineral deposition.…”

Diet of Mesozoic toothed birds (Longipterygidae) inferred from quantitative analysis of extant avian diet proxies

“…We also assign springtails (Collembola) to Soft and flies (Diptera) and termites (Isoptera) to Medium Invertebrates based on indentation hardness of their body parts compared to the above groups (compare [ 147 – 149 ]). Krill are very tentatively assigned to Medium as they lack the calcified shells found in other crustaceans ( [ 150 ], but see [ 151 ]). Using these divisions, we split invertivores into InvertivoreH, InvertivoreM, and InvertivoreS depending on the hardest group the bird consumes according to the Birds of the World database and references therein.…”