An atlas of the brain of the horseshoe crabLimulus polyphemus (original) (raw)
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Cell and Tissue Research, 2012
Comparative brain architecture of the European shore crab Carcinus maenas (Brachyura) and the common hermit crab Pagurus bernhardus (Anomura) with notes on other marine hermit crabs Abstract The European shore crab Carcinus maenas and the common hermit crab Pagurus bernhardus are members of the sister taxa Brachyura and Anomura (together forming the taxon Meiura) respectively. Both species share similar coastal marine habitats and thus are confronted with similar environmental conditions. This study sets out to explore variations of general brain architecture of species that live in seemingly similar habitats but belong to different major malacostracan taxa and to understand possible differences of sensory systems and related brain compartments. We examined the brains of Carcinus maenas, Pagurus bernhardus, and three other hermit crab species with immunohistochemistry against tyrosinated tubulin, f-actin, synaptic proteins, RF-amides and allatostatin. Our comparison showed that their optic neuropils within the eyestalks display strong resemblance in gross morphology as well as in detailed organization, suggesting a rather similar potential of processing visual input. Besides the well-developed visual system, the olfactory neuropils are distinct components in the brain of both C. maenas and P. bernhardus as well as the other hermit crabs, suggesting that close integration of olfactory and visual information may be useful in turbid marine environments with low visibility, as is typical for many habitats such as, e.g., the Baltic and the North Sea. Comparing the shape of the olfactory glomeruli in the anomurans showed some variations, ranging from a wedge shape to an elongate morphology. Furthermore, the tritocerebrum and the organization of the second antennae associated with the tritocerebrum seem to differ markedly in C. maenas and P. bernhardus, indicating better mechanosensory abilities in the latter close to those of other Decapoda with long second antennae, such as Astacida, Homarida, or Achelata. This aspect may also represent an adaptation to the "hermit lifestyle" in which competition for shells is a major aspect of their life history. The shore crab C. maenas, on the other hand seems to rely much less on mechanosensory information mediated by the second antennae but in water, the visual and the olfactory senses seem to be the most important modalities.
Glial Cells of the Central Nervous System in the Crab Ucides cordatus
Invertebrate Biology, 1999
Invertebrate glial cells show a variety of morphologies depending on species and location. They have been classified according to relatively general morphological or functional criteria and also to their location. The present study was carried out to characterize the organization of glial cells and their processes in the zona fasciculata and in the protocerebral tract of the crab Ucides cordatus. We performed routine and cytochemical procedures for electron microscopy analysis. Semithin sections were observed at the light microscope. The Thiéry procedure indicated the presence of carbohydrates, particularly glycogen, in tissue and in cells. To better visualize the axonal ensheathment at the ultrastructural level, we employed a method to enhance the unsaturated fatty acids present in membranes. Our results showed that there are at least two types of glial cells in these nervous structures, a light one and a dark one. Most of the dark cell processes have been mentioned in the literature as extracellular matrix, but since they presented an enveloping membrane, glycogen and mitochondriaintact and with different degrees of disruption -they were considered to be glial cells in the present study. We assume that they correspond to the perineurial cells on the basis of their location. The light cells must correspond to the periaxonal cells. Some characteristics of the axons such as their organization, ensheathment and subcellular structures are also described.
The Journal of Comparative Neurology, 1983
The musculature and associated skeleton, peripheral nervous system, and central projections of motor and sensory neurones of the two basal (thoracic and coxal) segments of the shore crab leg (fifth pereiopod, P5) were examined in vivo and with methylene blue or cobalt staining. Each of the four main basal muscles, promotorhemotor, levatorldepressor, controlling the thoracicocoxal (T-C) and coxo-basal (C-B) limb joints, respectively, comprises several more or less discrete fibre bundles (total 14), with little morphological segregation of different functional groups. The innervation to the basal leg region is carried in two nerve roots arising from the thoracic ganglion. The anterior Th-Cx root carries both sensory and motor axons, while the posterior Th-Cx root is purely motor. Three previously undescribed sensory branches (two "epidermal" nerves and an "accessory'' branch), in addition to that innervating the coxobasal chordotonal receptor, have been found in the distal part of the anterior Th-Cx root. Two clusters of 10 to 15 multipolar somata (d i m. 30-125 pm) are located proximally at the bifurcation of the accessory nerve and distally where the latter enters the basipodite. The cell bodies (diameter 20-80 pn) of basal leg motoneurones (total ca. 30) lie in the dorsal cortex of the ganglion, with somata of functionally related motoneurones tending to form discrete structural groups. The morphology of individual motoneurones conforms to the general arthropod pattern. All are confined to the ipsilateral hemiganglion and their main neuropilar processes run parallel and in close apposition to each other with overlapping dendritic structures. Sensory projections arising from the CB chordotonal organ also ramify in the region of the neuropile invaded by motoneurones. The possible physiological significance of such structural associations within the CNS is discussed, as are the functional implications of basal limb anatomy in general.
The Journal of …, 2012
Malacostracan crustaceans and dicondylic insects possess large second-order olfactory neuropils called, respectively, hemiellipsoid bodies and mushroom bodies. Because these centers look very different in the two groups of arthropods, it has been debated whether these second-order sensory neuropils are homologous or whether they have evolved independently. Here we describe the results of neuroanatomical observations and experiments that resolve the neuronal organization of the hemiellipsoid body in the terrestrial Caribbean hermit crab, Coenobita clypeatus, and compare this organization with the mushroom body of an insect, the cockroach Periplaneta americana. Comparisons of the morphology, ultrastructure, and immunoreactivity of the hemiellipsoid body of C. clypeatus and the mushroom body of the cockroach P. americana reveal in both a layered motif provided by rectilinear arrangements of extrinsic and intrinsic neurons as well as a microglo-
Geology, 2021
The central nervous system (CNS) presents unique insight into the behaviors and ecology of extant and extinct animal groups. However, neurological tissues are delicate and prone to rapid decay, and thus their occurrence as fossils is mostly confined to Cambrian Burgess Shale–type deposits and Cenozoic amber inclusions. We describe an exceptionally preserved CNS in the horseshoe crab Euproops danae from the late Carboniferous (Moscovian) Mazon Creek Konservat-Lagerstätte in Illinois, USA. The E. danae CNS demonstrates that the general prosomal synganglion organization has remained essentially unchanged in horseshoe crabs for >300 m.y., despite substantial morphological and ecological diversification in that time. Furthermore, it reveals that the euarthropod CNS can be preserved by molding in siderite and suggests that further examples may be present in the Mazon Creek fauna. This discovery fills a significant temporal gap in the fossil record of euarthropod CNSs and expands the ta...
Frontiers in Neuroanatomy, 2015
The Coenobitidae (Decapoda, Anomura, Paguroidea) is a taxon of hermit crabs that includes two genera with a fully terrestrial life style as adults. Previous studies have shown that Coenobitidae have evolved a sense of spatial odor localization that is behaviorally highly relevant. Here, we examined the central olfactory pathway of these animals by analyzing central projections of the antennular nerve of Coenobita clypeatus, combining backfilling of the nerve with dextran-coupled dye, Golgi impregnations and three-dimensional reconstruction of the primary olfactory center, the antennular lobe. The principal pattern of putative olfactory sensory afferents in C. clypeatus is in many aspects similar to what have been established for aquatic decapod crustaceans, such as the spiny lobster Panulirus argus. However, there are also obvious differences that may, or may not represent adaptations related to a terrestrial lifestyle. In C. clypeatus, the antennular lobe dominates the deutocerebrum, having more than one thousand allantoid-shaped subunits. We observed two distinct patterns of sensory neuron innervation: putative olfactory afferents from the aesthetascs either supply the cap/subcap region of the subunits or they extend through its full depth. Our data also demonstrate that any one sensory axon can supply input to several subunits. Putative chemosensory (non-aesthetasc) and mechanosensory axons represent a different pathway and innervate the lateral and median antennular neuropils. Hence, we suggest that the chemosensory input in C. clypeatus might be represented via a dual pathway: aesthetascs target the antennular lobe, and bimodal sensilla target the lateral antennular neuropil and median antennular neuropil. The present data is compared to related findings in other decapod crustaceans.
Electron microscopy of glial cells of the central nervous system in the crab Ucides cordatus
Brazilian Journal of Medical and Biological Research, 1999
Invertebrate glial cells show a variety of morphologies depending on species and location. They have been classified according to relatively general morphological or functional criteria and also to their location. The present study was carried out to characterize the organization of glial cells and their processes in the zona fasciculata and in the protocerebral tract of the crab Ucides cordatus. We performed routine and cytochemical procedures for electron microscopy analysis. Semithin sections were observed at the light microscope. The Thiéry procedure indicated the presence of carbohydrates, particularly glycogen, in tissue and in cells. To better visualize the axonal ensheathment at the ultrastructural level, we employed a method to enhance the unsaturated fatty acids present in membranes. Our results showed that there are at least two types of glial cells in these nervous structures, a light one and a dark one. Most of the dark cell processes have been mentioned in the literature as extracellular matrix, but since they presented an enveloping membrane, glycogen and mitochondriaintact and with different degrees of disruption -they were considered to be glial cells in the present study. We assume that they correspond to the perineurial cells on the basis of their location. The light cells must correspond to the periaxonal cells. Some characteristics of the axons such as their organization, ensheathment and subcellular structures are also described.
The predator and prey behaviors of crabs: from ecology to neural adaptations
Journal of Experimental Biology, 2017
Predator avoidance and prey capture are among the most vital of animal behaviors. They require fast reactions controlled by comparatively straightforward neural circuits often containing giant neurons, which facilitates their study with electrophysiological techniques. Naturally occurring avoidance behaviors, in particular, can be easily and reliably evoked in the laboratory, enabling their neurophysiological investigation. Studies in the laboratory alone, however, can lead to a biased interpretation of an animal's behavior in its natural environment. In this Review, we describe current knowledge – acquired through both laboratory and field studies – on the visually guided escape behavior of the crab Neohelice granulata. Analyses of the behavioral responses to visual stimuli in the laboratory have revealed the main characteristics of the crab's performance, such as the continuous regulation of the speed and direction of the escape run, or the enduring changes in the strength...