Pair Of Pereiopods Research Articles

Three New Species of Macrobrachium Bate, 1868 (Decapoda, Palaemonidae) from the Western Ghats of Kerala State, India

Three new species of Macrobrachium Bate, 1868, i.e., M. gurudeve, M. jayasreei, and M. kunjuramani, collected from the rivers Kabbini and Bhavani (east flowing rivers of Kerala State) are described here in detail. The most important diagnostic features of the species are: in M. gurudeve, the rostrum is broad with 7-9 upper (2 post-orbital) and 3-5 ventral teeth, characteristically arranged; telson broad, dorsal pairs of spines situated at the distal third, and inner distal pair of spines very short; 2nd cheliped with carpus shorter than chela, and fingers ¾ of palm; appendix masculina with 1 long and 4 short distal spinous setae and 13 and 4 stiff lateral setae in two rows; uropodal exopod without accessory spine. In M. jayasreei, the rostrum is very slender, with 7-8 (1 or 2 post-orbital) and 4-5 ventral teeth, maximum width of the rostrum at the level of 2nd ventral tooth, and distal ventral tooth widely separated from the remaining ones; telson slender with 2 pairs of dorsal spines at distal half, and inner distal pair very long and slender; 2nd pair of pereiopods with carpus longer than chela and fingers about half as long as palm, as well as palm longer than half carpus; appendix masculina with 6 distal, stiff spinous and 9 lateral stiff setae, uropodal exopod without accessory spines. In M. kunjuramani, rostrum broad with 7-9 (2 post-orbital) dorsal and 4-5 ventral teeth, characteristically arranged; cephalothorax shorter than rostrum; telson slender with dorsal spines situated at the distal half, and inner distal pair of spines slender; 2nd pereiopods with carpus longer than chela, fingers half as long as palm; appendix masculina with 3 distal, stiff spinous and 6 lateral stiff setae; uropodal exopod with accessory spine. The colouration of the three species is also described.

Evidence for filter‐feeding by the wood‐boring isopod, Sphaeroma terebrans (Crustacea: Peracarida)

AbstractThe morphology of the mouthparts and proventriculus of the wood‐boring isopod Sphaeroma terebrans has been described, with particular reference to its possible filter‐feeding abilities. Scanning electron microscopy revealed that while the mandibles might be designed to scrape pieces of wood from the cavity wall during boring, the rest of the mouthparts are better suited for microphagous feeding. Video observations of the mouthparts demonstrated the ability of S. terebrans to filter out particulate material from the water column, by means of the filtering setae on the first three pairs of pereiopods. The morphology of the gut was found to be largely similar to that of terrestrial herbivorous isopods; primary and secondary filter apparatuses were present, but the masticatory apparatus present in terrestrial herbivores was missing. The morphology of both the gut and mouthparts provides additional support for the assumption that wood is an unlikely food source for S. terebrans.

Differentiation of the fossil Hexapodidae Miers, 1886 (Decapoda: Brachyura) from similar forms

Distinguishing among members of the Hexapodidae Miers, 1886, the Asthenognathinae Stimpson, 1858, and the Chasmocarcininae Serène, 1964, is difficult in fossil specimens that lack preserved pereiopods or sterna. Members of the Hexapodidae are easily identified if sterna and pereiopods are present, because possession of four pairs of pereiopods and seven exposed sternites is diagnostic for the family. Several features of the dorsal carapace are useful in differentiating among genera assigned to that family and other subfamilies belonging to the Goneplacidae and Pinnotheridae; however, dorsal carapace characters are less useful in assigning taxa at the family or subfamily level. A key to the taxa discussed herein permits generic differentiation based upon the relative dimensions of the carapace, the shape and size of the orbits, the shape and size of the rostrum, carapace ornamentation, and the degree of fusion of abdominal somites in males.A new species ofPalaeopinnixaVia, 1966,Palaeopinnixa rotundus, is described from the Eocene Coaledo Formation of Oregon, USA. A new hexapodid genus and species,Globihexapus paxillus, is recognized from the Miocene Astoria Formation of Washington, USA.Prepaeduma decapodaMorris and Collins, 1991, is referred toHexapusde Haan, 1833.Viapinnixanew genus has been erected to accommodate material previously assigned toPinnixa(Palaeopinnixa) nodosaCollins and Rasmussen, 1992, andOrthakrolophoshas been named to accommodate three species ofPalaeograpsusBittner, 1875.Asthenognathus urretaenew species is described from the middle Eocene Centinela Formation of southern Argentina.

DIFFERENTIATION OF THE FOSSIL HEXAPODIDAE MIERS, 1886 (DECAPODA: BRACHYURA) FROM SIMILAR FORMS

Distinguishing among members of the Hexapodidae Miers, 1886, the Asthenognathinae Stimpson, 1858, and the Chasmocarcininae Serène, 1964, is difficult in fossil specimens that lack preserved pereiopods or sterna. Members of the Hexapodidae are easily identified if sterna and pereiopods are present, because possession of four pairs of pereiopods and seven exposed sternites is diagnostic for the family. Several features of the dorsal carapace are useful in differentiating among genera assigned to that family and other subfamilies belonging to the Goneplacidae and Pinnotheridae; however, dorsal carapace characters are less useful in assigning taxa at the family or subfamily level. A key to the taxa discussed herein permits generic differentiation based upon the relative dimensions of the carapace, the shape and size of the orbits, the shape and size of the rostrum, carapace ornamentation, and the degree of fusion of abdominal somites in males.A new species of Palaeopinnixa Via, 1966, Palaeopinnixa rotundus, is described from the Eocene Coaledo Formation of Oregon, USA. A new hexapodid genus and species, Globihexapus paxillus, is recognized from the Miocene Astoria Formation of Washington, USA. Prepaeduma decapoda Morris and Collins, 1991, is referred to Hexapus de Haan, 1833. Viapinnixa new genus has been erected to accommodate material previously assigned to Pinnixa (Palaeopinnixa) nodosa Collins and Rasmussen, 1992, and Orthakrolophos has been named to accommodate three species of Palaeograpsus Bittner, 1875. Asthenognathus urretae new species is described from the middle Eocene Centinela Formation of southern Argentina.

Decapod crustacean chelipeds: an overview.

The structure, growth, differentiation and function of crustacean chelipeds are reviewed. In many decapod crustaceans growth of chelae is isometric with allometry level reaching unity till the puberty moult. Afterwards the same trend continues in females, while in males there is a marked spurt in the level of allometry accompanied by a sudden increase in the relative size of chelae. Subsequently they are differentiated morphologically into crusher and cutter making them heterochelous and sexually dimorphic. Of the two, the major chela is used during agonistic encounters while the minor is used for prey capture and grooming. Various biotic and abiotic factors exert a negative effect on cheliped growth. The dimorphic growth pattern of chelae can be adversely affected by factors such as parasitic infection and substrate conditions. Display patterns of chelipeds have an important role in agonistic and aggressive interactions. Of the five pairs of pereiopods, the chelae are versatile organs of offence and defence which also make them the most vulnerable for autotomy. Regeneration of the autotomized chelipeds imposes an additional energy demand called "regeneration load" on the incumbent, altering energy allocation for somatic and/or reproductive processes. Partial withdrawal of chelae leading to incomplete exuviation is reported for the first time in the laboratory and field in Macrobrachium species.

Effect of aging on manipulative behavior in the cuttlefish, sepia

The cuttlefish is an active predator that is able to catch crabs of a size that is large relative to its own. The capture is followed by a complex manipulative behavior leading to paralysis of the prey by injection of a cephalotoxin. This manipulative behavior is relatively stereotyped, and earlier research has shown that the cuttlefish concentrates its bite on the articular basi-ischiocoxopodite membrane of the crab's fifth pair of pereiopods. By placing mechanical constraints on the base of the fifth pereiopods, we were able to demonstrate that this manipulative behavior presents a marked degree of stereotypy but is not rigidly fixed. Substantial behavioral differences, however, were observed between subadult and senescent cuttlefish. The existence of a reduction in behavioral flexibility in the older animals in reaction to the constraints is discussed.

The Mechanism of active capture of animal food by the Sergestid Shrimp Acetes Sibogae Australis

Combining the use of scanning electron microscopy and microcinematography with functional and behavioural observations has clarified many aspects underlying the feeding processes of the small planktonic sergestid shrimp Acetes sibogae australis. In captivity Acetes sibogae australis is an opportunistic feeder that uses four principal feeding modes to capture a wide size range of prey: Artemia nauplii (<0.33 mm), copepods (<1mm) and moribund Acetes (up to 25 mm). Prey capture is effected by combined actions of the first three pairs of pereiopods and the third maxillipeds before transfer to the more dorsal second maxillipeds. The second maxillipeds are the principal appendages used in securing, manipulating, sorting and rejecting prey before insertion into the vicinity of the inner mouthparts.

First attempt of interspecific hybridization between the shrimps Penaeus kerathurus Forskal,1775 and Penaeus japonicus Bate,1888

This paper reports preliminary studies designed to evaluate hybridization through natural mating and artificial insemination between female Penaeus japonicus Bate, 1888 and male Penaeus kerathurus Forskäl, 1775. Although both species were able to mature in captivity, natural copulation was not achieved. Different techniques, including manual squeezing in the base of the fifth pair of pereiopods, electrical stimulation and dissection, were used for the artificial insemination experiments. However, only dissection gave spermatophores. Stained sperm showed no malformations and its viability was very high. Seven out of 10 inseminations (70%) produced eggs, but the development of embryos was abnormal. It is suggested that the high genetic distance between these species is responsible for these results.

Gonopore development and sex change in the Antarctic shrimp Chorismus antarcticus (Caridea: Hippolytidae)

Chorismus antarcticus is the only protandrous hermaphrodite decapod species found on the Antarctic continental shelves. The morphological structures of the male and female gonopores were described and used to determine sex and to fix the size range at which the transition from male to female takes place. The parallel occurrence of male and female gonopores was found in all specimens. The presence of open gonopore flaps at both the third and fifth pair of pereiopods in individuals between 9 and 12 mm of carapace length (CL) is discussed as the morphological indicator of sex change. Few females occurred from 9 mm CL onwards, whereas all shrimps larger than 13 mm CL only had open female gonopores. This size corresponds exactly with the CL at which onset of oocyte development and female gonad production starts. Secondary sexual characters, the gonopore structures, seem to allow an accurate prediction of the size range at which hermaphrodite caridean decapods change sex.

Aspectos anatômicos e funcionais do aparelho reprodutor de Parastacus brasiliensis (von Martens) (Crustacea, Decapoda, Parastacidae)

The absence of morphological external characteristics that allow the recognition of the sex as well as the presence of both male and female gonopores in the same animal [except in some sexual forms of Parastacus nicoleti (Philippi, 1882)] gives rise to the hypothetical existence of some form of hermaphroditism in crayfishes belonging to the genus Parastacus Huxley, 1879. Specimens of Parastacus brasiliensis (von Martens, 1869) were collected in a rivulet at Mariana Pimentel municipality, Rio Grande do Sul, Brazil. In the laboratory they were reared and dissected. The results suggest that P. brasiliensis may be a sequential hermaphroditic species, but male and female gonadal tissues were not simultaneously present in the analized samples. In testes and ovaries two pairs of genital ducts are present; that connect, respectively, to the gonopores on the coxae of the fifth and the third pairs of pereiopods. In the females only the apertures and anterior ducts seem to be functional, while in the males only the apertures and posterior ducts may be functional. The existence of different degrees of obstruction in the female genital apertures and different degrees of projection in the male genital apertures was observed. The aspect of the gonopores were used to recognize, externally, the sex of animais.

TEN ARMS MEET TEN LEGS: DECAPODA (MOLLUSCA: CEPHALOPODA: SEPIOIDEA) SPAWN ON DECAPODA (CRUSTACEA: BRACHYURA: HOMOLIDAE)

ABSTRACT The first record of a homolid crab, Latreillopsis bispinosa, carrying cuttlefish eggs on its last pair of pereiopods is reported from the Philippine Islands. These eggs must have been laid directly on the crab by a species of Sepia.

Étude Du Développement Post-Embryonnaire D'Hemilepistus Reaumurii (Audouin, 1826) (Isopoda, Oniscidea)

The isopod Hemilepistus reaumurii is a species adapted to dry and semi-arid climates. In the population of El Hencha (southern Tunisia), the females enter into the reproductive period in April, the expulsion of the progeny happens in June. The male is different from the female by a genital apophysis and at birth the individuals are sexually undifferentiated and have only six pairs of pereiopods. As in other terrestrial Crustacea, there is an appearance of a median outline of the genital apophysis at the fourth moulting in the male, and of one pair of genital orifices at the fifth moulting in the case of the female. Beside those common features, we have also noticed particular characteristics in the development of the integument (ornamentation and colour) and in the aspect of pleopods 1 and 2.

Commensalism of a Bivalve, Peregrinamor Ohshimai, With a Thalassinidean Burrowing Shrimp, Upogebia Major

Ecological, behavioural and anatomical observations of a commensal bivalve, Peregrinamor ohshimai (Mollusca: Galeommatoidea), were carried out in a tidal mudflat in the Seto Inland Sea, Japan. The bivalve attached specifically to the longitudinal groove of the ventral side of the cephalothorax of thalassinidean burrowing shrimps, Upogebia major and Lf. narutensis (Crustacea: Decapoda), singly, dorso-ventrally and longitudinally, using its byssus, with its anterior part towards the head of the host. The mantle of the commensal bivalve has wide anterior (branchio-pedal) and narrow posterior (exhalant) apertures. In the living organism, the extended anterior edges of the mantle protrude from the shell and are inserted into the host's filtering basket, which is formed by the setal rows of the first two pairs of pereiopods and utilized for intercepting suspended matter. By beating its pleopods in a U-shaped burrow, the filter-feeding Upogebia shrimp creates water currents, which are also utilized by the commensal bivalve for filter-feeding. The shell length of the commensal bivalve was in proportion to the host's carapace length. This suggests that the veliger larva attaches to a young host and grows, thus maintaining the host-commensal morphological matching. The bivalve is a hermaphrodite and individuals of >8–5 mm in shell length were already producing eggs. Anatomical observations suggest that P. ohshimai is most closely related to the Montacutidae in Galeommatoidea.

PARTIAL PROTANDRIC HERMAPHRODITISM IN THE BURROWING CRAYFISH PARASTACUS NICOLETI (PHILIPPI, 1882) (DECAPODA: PARASTACIDAE)

ABSTRACT The question of intersexuality and hermaphroditism was investigated in the burrowing crayfish Parastacus nicoleti (Philippi, 1882) by examination of sexual characters of 473 specimens from Chile. Six sexual forms were initially identified, on the basis of the presence and absence of gonopores in the coxae of the third and fifth pair of pereiopods. Two basic sexual types were found in this species, primary females and protandric hermaphrodites, the latter consisting of 1 male-phase and 3 female-phase forms ― 1 transitional form and 2 female-phase forms-which originate from protandric hermaphrodites in male phase, through 2 slightly different ways. Permanent secondary sexual characters associated with incubation of eggs were identified in adult primary females and in the 2 protandric forms in female phase. Both the gene-dispersal model and the size-advantage model may be used to explain different aspects of this partial protandric hermaphroditism.

Effects of eyestalk ablation and limb amputation on the moult cycle of the shrimpPenaeus chinensis

The shrimp Penaeus chinensis at moult stage Do were subjected to one of the three following treatments: bilateral eyestalk ablation, amputation of the fifth pair of pereiopods, and both of the above treatments. Two consecutive ecdyses after treatments were followed. Intact animals served as control. Precocious moulting was exhibited in all treated groups. Eyestalk ablation shortened the time to the first ecdysis more than does limb amputation. Additive effect was found in shrimps receiving both treatments. The duration between the first and second ecdyses in treated shrimps was shorter than that of intact animals, but the durations in the three treated groups were not significantly different from one another. Regenerates of limbs appeared after the second ecdysis following limb amputation. Further, change of body colour from black and green to red and white was observed in shrimps with eyestalk ablation.

Induced Spawning of the Decapod CrustaceanSicyonia ingentis

The dark portion ofthe light/dark cycle initiated pre-spawning behavior in the penaeid shrimp, Sicyonia ingentis. Persistent swimming in the water column (pre-spawning behavior) correlated well with ovulation. Over 96% of the animals that exhibited active swimming behavior were ovulated as determined by the presence of green oviducts and/or their subsequent spawning. More than 87% of the ovulated animals responded to probing of the ovipores, located at the bases of the third pair of pereiopods, by immediately spawning. The ova from probe-induced spawns underwent a normal developmental sequence. A reliable and predictable technique for the assessment of ovulation and acquisition of viable ova from S. ingentis is described.

ONYCOCARIDITES ANOMODACTYLUS, NEW GENUS, NEW SPECIES (DECAPODA: PALAEMONIDAE), A COMMENSAL SHRIMP FROM THE ARAFURA SEA

ABSTRACT A new genus, Onycocaridites, is proposed for two specimens of a palaemonid shrimp found inhabiting a sponge in a depth of 60 m in the southern Arafura Sea. The shrimps, representing a new genus and species, are described and illustrated. The new genus is most closely related to Onycocaridella Bruce, 1981, and the only species, O. anomodactylus, is readily separated from all palaemonid shrimps by the unique differences between the dactyls of the third pair of pereiopods (very long, slender, and simple) and those of the fourth and fifth pereiopods (short, stout, and strongly biunguiculate).

Carrying Behavior in Brachyuran Crabs

ABSTRACT Carrying is a behavior in which the last one or two pairs of pereiopods of a crab are used to lift and hold an object dorsally over the body. This behavior is found in the families Homolidae, Latreilliidae, Dromiidae, Tymolidae, and Dorippidae. Crabs that carry have subdorsal pereiopods ending in spines, hooks, subchelae, chelae, or curved dactyls. Subdorsal pereiopods ending in small chelae also are found in the Homolodromiidae. All of the families that carry have been classified in the section Dromiacea except for the Dorippidae. I suggest that carrying is a conservative behavioral pattern in brachyuran crabs, and that it may be useful in determining family relationships.

Lift based mechanisms for swimming in eurypterids and portunid crabs

ABSTRACTThe striking morphological similarity that exists between appendages of the extant portunid crabs, such asCallinectes sapidus, and those of the extinet eurypterids has long been noted. The fifth pair of pereiopods in blue crags and other portunids are modified to form the broad, flat, highly mobile ‘swim paddles.’ A nearly identical modification is seen in the sixth pair of prosomal appendages of many eurypterids. The similarities are due to convergence and not to shared descent.The kinetics of blue crab swimming were studied using high speed films. The animals are capable of slow upwards locomotion (‘hovering’) and rapid sideways swimming. The blue crab paddles apparently act as reciprocating hydrofoils, employing well-understood principles of lift and thrust generation to overcome the animal's weight and drag. Experimental studies indicated that the paddles are capable of producing appreciable amounts of lift. Drag on the body and paddles was also determined. Resxults are similar to those obtained in previous studies of bird and insect flight.The physical principles employed to study blue crab swimming can be applied to the study of eurypterid locomotion. The eurypterid paddles may have functioned as hydrofoils, producing lift and thrust on forestroke and backstroke. Eurypterids were probably highly agile and manoueverable swimmers, capable of hovering and of high speed swimming. This model predicts observed morphological correlates. Predicted morphological correlates of earlier models (often based on analogies withLimulus) were not found.The observed convergence between eurypterids and blue crabs may have resulted from similar functional constraints and parallel phylogenetic histories.

Structure and Function of Cuticular Sensilla of the Lobster Homarus Americanus

ABSTRACT Chemosensory neurons and mechanosensory neurons innervate all the cephalothoracic appendages of the lobster Homarus americanus, including the antennules, antennae, six pairs of mouthparts, and five pairs of pereiopods. The structure and sensory function of sensilla on these appendages are described. Sensilla on the pereiopods and maxillipeds can be classified morphologically and physiologically. Smooth setae and squamous setae are the primary setal types in the rows and tufts of hairs on the walking legs; they also are found on the maxillipeds and, less abundantly, on the crusher and seizer claws. Serrate setae are common on the maxillipeds and the third and fourth walking legs. Hedgehog hairs are located on the cutting edges of the claws of the first two pairs of walking legs and on apposable cuticular surfaces on the last two segments of the fourth pair of walking legs. All four of these types of sensilla are both mechano- and chemosensitive. Sensilla sensitive to mechanical but not to chemical stimuli include peg sensilla, which are small sensilla situated in articulated sockets within cuticular depressions and are distributed over the surface of the carapace, pereiopods, and maxillipeds. Other mechanoreceptive sensilla include cuticular articulated peg organs (=CAP organs), located on the pereiopods and on the third maxillipeds, and campaniform sensilla, found on the antennae and antennules. Exclusively chemosensory sensilla were not found.