Hooded sensilla homologues: Structural variations of a widely distributed bimodal chemomechanosensillum

Abstract

A diversity of sensilla has been described in crustaceans, both across species and within a given species. However, few homologous setal types have been identified in crustaceans. In this study we examined setae with features of the hooded sensillum, which is a class of bimodal chemomechanosensilla first identified on antennules of the Caribbean spiny lobster Panulirus argus. We examined the antennules of 13 species representing seven families of malacostracan crustaceans, and most body surfaces of P. argus, and compared the sensillar morphology from different species and from different body regions to identify interspecific and intraspecific homologues of hooded sensilla. Our results show that sensilla with morphological characteristics of antennular hooded sensilla are present and have a similar pattern of distribution on the antennules of reptantian species representing three families (Palinuridae and Scyllaridae of the Achelata and Nephropidae of the Homarida). Furthermore, hooded sensillar homologues are present on most body surfaces of P. argus. However, there are intraspecific and interspecific variations in the morphology of these sensilla. We present evidence that supports the idea that postembryonic changes in individual sensilla may be responsible for some of these morphological variations. Despite these variations, we conclude that the sensilla are homologues, because they have several common characteristics, similar positions on the body surface, similar substructures, a continuum to their morphological variations, and morphological variation that is correlated with phylogenetic similarity. Taken together these results support the idea that the hooded sensillum is a singular and biologically important sensillar type that has a broad distribution.

Dual antennular chemosensory pathways can mediate orientation by Caribbean spiny lobsters in naturalistic flow conditions

“…sufficient to mediate food localization behavior In addition to the antennules, chemosensilla are concentrated on several other body regions of the spiny lobster, including the walking legs, mouthparts and second antennae (Derby and Atema, 1982;Cate and Derby, 2002a;Garm et al, 2003). Work on other decapod crustaceans has shown that leg chemoreceptors in particular can aid in orientation as the animal approaches the source of an odor stimulus (Devine and Atema, 1982;Moore et al, 1991;Keller et al, 2003).…”

Habitat-Related Divergence among Tailfan Sensory Systems in Reptantian Decapod Crustaceans

“…Although some of these differences might prove to be correlated with mechanical aspects of setal function (stiffness, pliability, surface area, etc. ), at least some may be ontogenetic [Factor, 1978;Derby, 1982;Schmitz, 1992b;Cate and Derby, 2002b]. There is some morphological variation among setae of a given type in our animals, particularly in Category I, but we saw no utility in finer classification beyond plumose or pappose type to which no functional correlates could be suggested.…”

“…If they are, they may have replaced hooded sensilla, which occur on the abdominal pleura and telson of the macruran reptantian Panulirus argus [Cate and Derby, 2002a]. Interestingly, if all peg sensilla are bimodal [Schmidt, 1989], as well as homologues of hooded sensilla [Cate and Derby, 2002b], the mole sand crab telson would bear two types of bimodal receptors.…”

Smelling, feeling, tasting and touching: behavioral and neural integration of antennular chemosensory and mechanosensory inputs in the crayfish

“…Beaked sensilla are less compliant than standing feathered sensilla, and therefore they probably are not normally receptors for near-field hydrodynamic stimuli. As discussed in greater detail below, there are anatomical reasons to conclude that beaked sensilla are bimodal contact chemo-mechanoreceptors, possibly similar in their responses capabilities to, for example, the hooded sensilla found on the antennular flagella of spiny lobsters (Cate and Derby, 2002a;Cate and Derby, 2002b). The arrangement of beaked sensilla along the shaft of the antennular flagella is not random (Fig.3C).…”