Marco Vannini

• University of Florence

The gastropod Cerithidea decollata typically feeds on mud at the mangrove soil surface at low tide and rests on Avicennia marina trunks throughout high tide. Tens of individuals can be observed climbing the trunks and clustering, 2-3 hr before the incoming high tide, approximately 40 cm higher than the level that the tide will reach. As soon as the...

Coenobita hermit crabs succeeded in their adaptation to land thanks to their shell and to the possibility of carrying water within it. Such a water reserve may play several roles: to compensate for dehydration, to keep the gills and abdomen surface sufficiently wet to allow gas exchange, to reduce temperature through evaporation and to facilitate o...

Honest-advertisement models of sexual selection suggest that condition-dependent male secondary sexual characters could function as reliable signals of male quality, enabling females to discriminate among potential partners, both in the pre- and post-copulatory phases. In this context, many studies have revealed the importance of promiscuous mating...

Testudo hermanni hermanni is becoming seriously endangered throughout its range. It has a scattered distribution, with a small number of residual populations found in Spain, France and Italy. In this study we sampled a population of T. h. hermanni from Southern Tuscany (Massa Marittima, Grosseto), composed of native and introduced individuals (reco...

Molara is a small island belonging to the Marine protected Area Tavolara—Punta Coda Cavallo, in Sardinia. During 2006–2007, a bio-monitoring program reported a strong presence of the black rat, Rattus rattus, on Molara island. Rat predation has detrimentally affected the unique biodiversity of this island, thus, in 2008 an eradication campaign was...

The genetic connectivity level of the benthic crab Pachygrapsus marmoratus was assessed within the Tuscan Archipelago, an area between the Ligurian and Tyrrhenian Seas, Italy. The archipelago comprises 7 islands lying inside the largest marine protected area of the Mediterranean Sea. We genotyped a total of approximately 230 individuals from 8 popu...

Sperm storage is widespread in many vertebrate groups, and it is frequently associated with promiscuous mating systems. Chelonian species are one of the most outstanding examples of a promiscuous group capable of long-term sperm storage; specialized structures have evolved within the oviducts of these vertebrates to ensure sperm vitality across rep...

Sperm storage is widespread in many vertebrate groups, and it is frequently associated with promiscuous mating systems. Chelonian species are one of the most outstanding examples of a promiscuous group capable of long-term sperm storage; specialized structures have evolved within the oviducts of these vertebrates to ensure sperm vitality across rep...

European tortoises of the genus Testudo are becoming seriously threatened mainly due to habitat urbanization and illicit pet trade. In this study we tested the cross-amplifications of 23 microsatellite genetic markers (isolated from Testudinidae and Emydidae) in five (sub)species of the genus Testudo. A subset of 8–10 polymorphic loci was defined a...

Many Indo-Pacific mangrove macroinvertebrates are herbivorous and heavily dependent on leaf litter. As a consequence, fallen leaves become a limiting factor and competition occurs among conspecifics and heterospecifics. Neosarmatium meinerti and Cardisoma carnifex are two of the most common herbivorous crabs of the landward mangrove belt in East Af...

Locomotor activity in a field population of the freshwater crab, Potamon fluviatile, was studied during the breeding season by means of radio-telemetry and by direct counts of active animals along a transect of the stream. The basic pattern of crabs' locomotor activity can be described as a sequence of short distance movements around the shelters (...

Sesarma leptosoma an East African mangrove-dwelling crab, migrates twice a day from a system of known dens among the roots to well-defined feeding areas in the branches of trees, reaching 15 m high. Field experiments were performed to test whether chemical or visual cues are involved in the orientation and homing of this species to reach their feed...

Cottus gobio Linnaeus, 1758 has been declared protected species both at local and national level, and should be object of particular attention, especially in Appennine’s area, where populations are getting rarefied. This research is about some C. gobio populations located in the Province of Prato, concerning in particular reproduction aspects. Obta...

The influence of some environmental parameters, i.e. dissolved oxygen, water temperature, Ca concentration, pH, conductibility, on populations of the river bullhead, Cottus gobio, in Northern Apennines (Tuscany) has been considered. The bullhead seemed to prefer waters with low levels of calcium. The Discriminant Function Analysis (DFA) showed cong...

The presence of boundaries to dispersal has been recently documented for many Indo-West Pacific (IWP) species with planktonic propagules and a widespread distribution. We studied the phylogeography of the mangrove crab Neosarmatium meinerti (Brachyura: Sesarmidae) and the phylogenetic relationship to its presumed sister species N. fourmanoiri in th...

Urban habitats are increasing worldwide and represent new potential environments for many species of animals, in particular birds. As a result of contact with humans, urban wildlife can experience ecological and ethological modifications, mainly regarding parental and feeding behaviour. One of the most common birds in urban landscapes is the mallar...

Sesarma lepzosoma is the only species of crab inhabiting the mangrove swamps of East Africa which can climb to the top of tall mature trees, where it feeds on fresh leaves. Twice daily, in the morning and evening, this crab performs mass migrations towards the canopy and spends about three hours on the tree-tops. At dusk it descends to spend the ni...

Radio-telemetry was used to investigate locomotor activity rhythms in a field population of the freshwater crab Potamon fluviatile. Fourteen adult specimens were radio-tracked almost continuously over a 13-day period along a hill stream in Tuscany, Italy. A rough nychthemeral movement pattern was found in some animals of both sexes. None of the cra...

Metopograpsus thukuhar is a very common grapsid in the Indo-Pacific mangroves but is found only occasionally in a non-mangrove environment. Field observations investigated its spatial and temporal strategies and clarified its predatory abilities. Gut-content analysis was used to assess its natural diet. Metopograpsus thukuhar was mainly active duri...

Young Cardisoma carnifex were found living within burrows of conspecific adults, in diverticula starting from the main branch of the burrow. Their gill chamber structure is much less adapted for air-breathing than that of the adult. The young spend at least three years in this environment, probably feeding on leaves remaining from the adult meals....

a b s t r a c t Terebralia palustris is a common mud-whelk present at a particularly high density in all Indo-West Pacific mangroves. Young snails feed on nothing but mud while larger specimens are able to feed on fallen leaves too. In Kenya (Mida Creek) under the canopy, competition for mangrove leaves can be very high due to the high density of S...

Individuals of Cerithidea decollata periodically migrate along mangrove trees, resting on the trunks during high water, and foraging on the surrounding muddy platform during low water. Groups, ranging from tens to hundreds of snails, aggregate on the trunks well before the incoming tide (1-2 h) at a level that will not be reached by the high tide,...

The gastropod T. palustris is one of the major species responsible for leaf consumption and degration within the Indo-Pacific mangrove forests, and it strongly competes with herbivorous sesarmid crabs in consuming fallen leaves. This snail feeds at high and low tides and it is able to locate food items by means of chemical cues. The aim of this stu...

The vertical migration on mangrove trunks of the gastropod Cerithidea decollata was followed for 5 weeks, in a Kenyan mangrove. Most of the times, snails forage on the mud surface, during low tide, and climb back on trees well before the incoming tide. As soon as the sea retreats, the downward migra-tion takes place and the snails spread again on t...

The “genetic erosion” hypothesis posits that heavy metal stress is related to a loss of genetic diversity at the population level. The genetic diversity of natural populations can, however, be affected by natural processes as well as by human impact. We studied the relationship between heavy metal bioaccumulation and genetic variability in the inte...

In Mida Creek, Kenya (3°20′S, 40°5′E), at high water, the snail Cerithidea decollata dwells on the trunks of mangrove trees (Avicennia marina), while during low water it migrates to the ground, foraging at various distances from the trunk, where it aggregates again well before the incoming tide. Snails from the upper shore level are 150–200m distan...

Using a multi-dimensional ecological design, this study aimed first to analyse whether local environmental conditions can account for the spatial segregation of two Italian native decapods, the crayfish Austropotamobius italicus and the river crab Potamon fluviatile, in Central Italy freshwater ecosystems. Second, we aimed to analyse which environm...

We investigated the choice preferences exhibited by the spider crab Inachus phalangium when using algae for feeding and masking, together with the pattern of decoration present on the body surface and the morphology of the setae, which are used to attach masking material. We showed that feeding and masking preferences are decoupled, and that I. pha...

The behaviour of Cerithidea decollata, a common western Indian Ocean mangrove tree climbing gastropod, was studied in Mida Creek, Kenya. At the study site, this snail mainly lived in Avicennia marina dominated areas, i.e. in the mangrove belt between high water spring tide and high water neap tide levels. Not a single individual was found on the le...

Grapsoid and ocypodoid crabs receive a lot of attention in the literature due to their predominance and important role as primary and secondary consumers in intertidal as well as supratidal marine habitats. They are especially species-rich in the tropics, where they have been found to repeatedly invade terrestrial and freshwater habitats. However,...

1. The patterns of relative and absolute growth and the reproductive biology of the freshwater crab Potamon fluviatile were studied in a natural population inhabiting a hill stream close to Florence, Italy, over an annual cycle. Periodical inspections of a stretch of the stream were made and morphological and anatomical analysis carried out. 2. As...

This study investigated the presence/absence in Prato Province (Tuscany, Italy) of three crustacean species (the river crab Potamon fluviatile, the white clawed crayfish Austropotamobius italicus and the grass shrimp Palaemonetes antennarius) and five fish species (the Arno goby Padogobius nigricans, the bullhead Cottus gobio, the soufie Leuciscus...

Biological rhythms with lunar components are common in nature. In the sea, the moon's gravitational pull on earth is the principal cause of the tides, which normally reach maximum amplitudes every new and full moon. Many populations synchronize spawning to this time. Some choose either the new or the full moon, implying that moonlight is important;...

Several crab species of the families Sesarmidae and Grapsidae (Crustacea: Brachyura: Grapsoidea) are known to climb mangrove trees. They show different degrees of dependence on arboreal life, with only a few of them thriving in the tree canopies and feeding on fresh leaves. Some of the sesarmid tree-dwelling crabs share a number of morphological ch...

The use of the pleopods was investigated in two species of Diogenid hermit crabs, Dardanus arrosor and D. calidus. A transparent glass shell was used to observe the movements of the pleopods in hermit crabs. The movements consisted of periodic, irregular beating, which generated an irregular flow of the water within the shell.A strong, regular beat...

The ecology and taxonomy of an interesting species of tree-living freshwater crab from the East Usambara mountains, Tanzania, and from the Shimba Hills, Kenya, East Africa is described. This phytotelmic decapod crustacean belongs to a new species of potamonautid freshwater crab in the genus Potamonautes MacLeay, 1838, which is described. This is on...

Although the role of macroinvertebrates in the nutrient cycling of the Indo-Pacific mangrove ecosystems is now a paradigm of ecological research, most of the research and scientific assumptions deal with decapod crustaceans alone. However, decapods are not the only representatives of mangrove macrobenthos and in certain mangals they are surely outn...

Scylla serrata (Decapoda: Portunidae) is a swimming crab that is widespread in the Indo-Pacific region and commonly found in estuarine and mangrove waters. An extended planktonic larval phase suggests high dispersal potential and the possibility of extensive gene flow between conspecific populations at least on a geographic mesoscale (tens to hundr...

The aim of this study was to identify the feeding habits of the European intertidal crabPachygrapsus marmoratus . Since this species is widely distributed in southern Europe, four south-western European sites far apart from each other were selected: southern Portugal, central Portugal, central Tyrrhenian coast, Italy, and northern Adriatic coast, I...

The aim of this work was to determine the abundance of crabs inmangrove communities along a latitudinal gradient along the eastern coastof Africa from 4S to 32S. Surveys were made atMombasa (Kenya), Zanzibar (Tanzania), Maputo (Mozambique) and in theTranskei (South Africa). Crabs were estimated at three designated levelsin the mangroves by visual c...

The climbing crab Sesarma leptosoma colonizes the mangrove roots and canopy of East African mangrove swamps, an intricate three-dimensional habitat in which it orients itself visually. To ascertain if vision helps this tree crab to detect dangers such as predators, we used dummy objects: (1) a preserved specimen of its predator, the crab Epixanthus...

Numerous studies have highlighted the importance of crabs within mangrove ecosystems, but tested methods of enumeration are virtually non-existent. The aim of the present study was to assess the accuracy of quick, non-invasive methods for estimating the population density of three species of mangrove crabs in East Africa: Uca annulipes, Sesarma gut...

This field study investigated the spatial strategies and homing ability of two East African fiddler crabs, Uca lactea annulipes and Uca vocans hesperiae, using various experimental procedures. A clear-cut spatial segregation between the two species was observed, with U. l. annulipes occupying areas even a few centimetres above U. v. hesperiae. Fema...

Large numbers of the snail Terebralia palustris (Linnaeus) (Potamididae; Gastropoda) are frequently observed feeding in a cluster on a single fallen mangrove leaf, yet none are present on leaves nearby. Consequently, we investigated the food-finding ability of T. palustris in a Kenyan mangrove forest using field experiments. We estimated the attrac...

Epixanthus dentatus (Crustacea: Brachyura: Eriphiidae) is a predator crab, commonly inhabiting East African mangroves, whose nocturnal and elusive behaviour usually prevents analysis of its natural diet and prey selection. The present study was carried out on a population inhabiting a peculiar mangrove habitat in which E. dentatus produces heaps of...

From 1970 to 1997, 482 Portunidae were collected from various intertidal environments along the southern Somalian coast and, to a lesser extent, from Kenya and the Mascarene Islands. The material belongs to 39 species of which 13 are new for the Somalian coast, 5 for the East African coast and 2 for the western Indian Ocean: Charybdis hawaiensis Ed...

We investigated whether Thalamita crenata, a swimming crab found on the East African intertidal flats, uses landmarks to locate its refuges. We modified the visual panorama of an intertidal flat, using conspicuous movable objects, and conducted homing trials with the local population of swimming crabs. In the first set of trials, after being moved...

 In a Kenyan mangrove, we studied the interactions between the gastropod Terebralia palustris and the crab Neosarmatium smithi when foraging on decaying mangrove leaves. Interactions are considerable on account of their wide overlap in zonation (Rhizophora mucronata belt), food items (mangrove leaves) and activity window (diurnal low water). The sn...

The activity patterns and use of space of the mangrove dweller Selatium elongatum were studied in the field, in combination with gut content analyses for evaluation of the crab's natural diet. This sesarmine crab proves to be one of the most adapted to climbing and living on mangroves. Moreover, S. elongatum showed a strong preference for being act...

The spatial strategies and activity patterns of two populations of Pachygrapsus marmoratus (Fabricius), from Italy and Portugal, were studied in the field. The Mediterranean site was a non-tidal splash zone about 30 cm wide, while the Atlantic site was a 30 m wide intertidal belt. Almost all P. marmoratus of both populations were active on the emer...

The stomachs of 194 crabs belonging to 11 species, commonly inhabiting mangrove areas, were collected in two Kenyan mangrove forests, in Gazi Bayand Mida Creek, and their contents were analyzed. Both the stomach fullness (a subjective estimation) and the composition (the plant:animal matter ratio) of the food ingested were recorded. Results show th...

A significant portion of the population of Charybdis longicollis (Decapoda: Portunidae) along the Mediterranean coast of Israel is parasitized by the rhizocephalan Heterosaccus dollfusi. The behaviour of the parasitized crabs, in different stages of infection, is examined and compared with the behaviour of nonparasitized crabs. Locomotion, rest, bo...

The predatory patterns and spatial strategies of Epixanthus dentatus were studied in a mangrove creek on the Kenyan coast, together with laboratory analysis aimed at assessing the natural diet. This xanthoid fed on almost all the slowly moving invertebrates common in the forest and actively preyed at night, using an ambush technique. Epixanthus den...

The tree crab Sesarma leptosoma Hilgendorf migrates up the mangrove trunks twice a day, both in the morning and in the evening, leaving its refuge near the tree base to feed on fresh leaves. In spite of the 150 cm of tide excursion at the base of the trees, the timing of the migrations seems largely controlled by nontidal factors. The timing of the...

The capability of terrestrial hermit crabs to detect volatile chemicals in the air does not only concern food-related substances, but may also be used to identify water-related cues. Coenobita rogosus and C. cavipes from Kenya (which in the field exhibit, respectively, high and low levels of terrestrial adaptation) were tested in an olfactometer, w...

ABSTRACT Thalamita crenata is one of the most common swimming crabs of the mangrove creeks of the East African coast. In Mida Creek, Kenya, this species inhabits the extreme seaward fringe of the mangrove swamp and the intertidal platform in front of the mangal, sheltering in small pools during low tide. Gut content analysis reveals that T. crenata...

Sesarma leptosoma is a small grapsid crab which lives on the roots of mangrove trees of the East African coast and migrates twice a day to and from the canopy, spending the hottest hours of the day and most of the night within the root system. When not feeding on the canopy this crab hides in small crevices which the aerial roots of Rhizophora mucr...

This review on homing in decapods, which has been shown by Herrnkind (1983) and Wehner (1992), indicates how scarce our knowledge is, not only on the physiological mechanisms involved in such behaviour but also on the reality and extent of the behaviour itself.The case studies cited (first part) show that among decapods (only “reptants” are conside...

The activity rhythms of the swimming Portunid Thalamita crenata have been studied on the basis of crab sightings in surveys along three transects of a mangrove swamp in Kenya. Activity is well matched to the environmental regime and is prevalent during the high tides. However, activity does not occur over the whole of the high tide, but is confined...

Sesarma leptosoma is a mangrove crab that lives among the mangrove roots and migrates twice a day to the canopy to feed on leaves and leaf-buds. An experiment was performed by covering the whole root system of mangrove trees with white and black tents, thus differentially reducing the light intensity reaching the crabs, in order to investigate whet...

On the Kenyan coast, Thalamita crenata confines itself to a defined system of crevices and forages, swimming in a few cm of water, within a radius of about 5 m from its shelter. A field study was designed to analyse this crab's ability to find its shelter after being moved away from it. Crabs were displaced, being kept under water, with full vision...

In decapods, no analysis has ever been conducted of the force exerted by chelae, and the role that strength plays in the establishment of hierarchies. For this purpose, a device was designed to measure the force produced by the major chela in the freshwater crab Potamon fluviatile, where dominance hierarchy and agonistic behavioral patterns have pr...

To address the question of hermit crab clustering, 11 clumps composed of Clibanarius laevimanus were studied in the mangal of Mida Creek, Kenya in 1988. Hermit size and sex were analyzed, as well as the type, dimensions, and status of their shells. Empty gastropod shells constituted a limiting factor on the population studied; the architectural tra...

Sesarma leptosoma, somewhat similar to the Atlantic related species, Aratus pisonii, is an East-African mangrove crab which spends its entire life on the roots and branches of mangrove trees (mostly Rhizophora mucronata, Bruguiera gymnorhiza and Ceriops tagal). S. leptosoma never enters the water, nor does it ever venture onto the free mud surface...

Heteromysis harpax (Mysidacea) is an obligate commensal, which lives in pairs inside the shells of various species of tropical Dardanus hermit crabs. Preliminary observations with transparent glass shells were carried out in the laboratory in Kenya. Heteromysis harpax probably employs both visual and chemical cues to identify suitable shells for ha...

Merguia oligodon (De Man 1888), is one of the two known species of semi-terrestrial shrimp. It is very common in some Kenyan mangroves, where it can be found among the aerial roots of Rhizophora mucronata. Active only at night, M. oligodon can be seen climbing spontaneously up the mangrove roots and trunks up to 80 cm above ground level. At high wa...

Young Pardosa hortensis not only need their mother's help to leave their cocoon once developed (about 20 days), as they are unable to open it by themselves, but also during the period they are carried around in the cocoon. Using radioactive markers, indirect evidence revealed that the mother periodically opens the cocoon to feed her young and resea...

The proximate and ultimate factors of the clustering behavior in the mangal-dwelling hermit Clibanarius laevimanus have been studied at Mida Creek, Kenya. First, field experiments showed that the hermits correctly oriented towards their clustering sites after deprivation of references from the sky, landscape, and substrate. Second, the pros and con...

Two commensal crustaceans, Heteromysis harpax Hilgendorf 1878 (Mysidacea) and Aretopsis amabilis De Man 1910 (Decapoda Alpheidae) were found inhabiting the shells of hermit crabs (five species of Dardanus Paulson 1875) collected in Somalia and Kenya. The two species were never found together in the same shell. In Kenya, where alpheids seem to be ab...

Some dynamic patterns of clustering in the mangrove‐dwelling hermit crab Clibanarius laevimanus were studied during a semi‐lunar tide cycle in Kenya. Clusters composed of hundreds of quiescent individuals occurred at every low tide, developing either on the mangrove prop roots or in the open (but always within a 4‐m belt from the mangrove fringe)....

Larvae of Euscorpius carpathicus settled on conspecific adults can distinguish between males and females on a chemical basis, with females being preferred to males. The preference for different females depends on their reproductive phase, with mothers being the most preferred. E. carpathicus females offer a better chance of survival against dehydra...

Proximate and ultimate factors influencing clustering behaviour in the mangal-dwelling hermit crab Clibanarius laevimanus Buitendijk 1937 were studied in Kenya. First, a reasonable hypothesis to understand the homing performance of this species is menotactic or compass orientation towards the tidal current. Second, clustering may serve as a “shell...

The behavior and ecology of two mangrove crabs,Sesarma meinerti De Man, 1887 andCardisoma carnifex (Herbst, 1794) were investigated at the beginning of the rainy season (October–November 1988) at Mida Creek, Kenya. Both species occupy upper intertidal levels, above mean high-water neap, and completely overlap in their zonation. Each burrow lasts ca...

The cocoon care of Pardosa hortensis (Lycosidae) was investigated. A transmission of substances, from the mother to the spiderlings, after cocoon production, was found. Following radioactive leukine or tritium ingestion by the mother, C14 and H3 were found mainly incorporated in the silk layer and in the spiderling's body respectively, of substitut...

The habit of clustering was studied within a semilunar tide cycle in the man-grove-dwelling hermit crab Clibanarius laevimanus. Notwithstanding the stability with time of aggregation size, shape, spatial position and shell-size composition together with the relatively strong site-attachment showed by these hermits, one individual's probability of c...

Thirty-nine genera and 80 species of xanthoid crabs are identified from recent collections in Somalia and their habitats discussed. Most are new records for Somalia and 23 were previously unknown from the East African coast. Descriptions and illustrations are given for two new species: Cymo lanatopodus and Hypocolpus pardii.

The spatial strategy of the hermit crab Clibanarius longitarsus was studied during a semilunar tidal cycle in a mangrove swamp in Kenya. This species is isospatial, being active at HW and taking refuge during its wrong phase (air) within the mangrove roots at LW. However, as revealed by radio‐telemetry, these animals (as well as other decapods) may...

Activity and clustering in two intertidal species of hermit crabs, Clibanarius virescens and Calcinus laevimanus, were studied during a semilunar tide cycle in Somalia. Three groups were marked and examined throughout 16 low waters, and 12 samples of clustered and scattered crabs were collected from similar habitats. During high water, the animals...

Adult and young individuals of the shrimp Palaemonetes antennarius (Milne Edwards) collected in the field (experienced), and laboratory-born (inexperienced) young were tested in a transparent bowl screened to hide the surrounding landscape from view. Field individuals were collected in South Tuscany, Italy, and testing was carried out in spring-sum...

Eriphia smithi is a very common East African intertidal xanthoid crab. Its dietary input is based mainly in algal grazing (during the day) and predation (particularly at night). Predation appears quite opportunistic and mostly directed at crustaceans and molluscs, among which bivales largely predominate. Echinoderms are actively avoided and, contra...

Morphometry and population structure have been investigated in a large sample (about 800 specimens) of the tropical Xanthoidea Eriphia smithi MacLeay 1838 (Decapoda Brachyura), inhabiting a rocky cliff in Somalia. The analysis of relative growth in two sexual dimorphic characters (i.e., chelipeds and abdomen) showed that both sexes undergo the pube...

Locomotor activity in the freshwater crab, Potamon fluviatile, was studied both in the field, by direct counts of animals along a stream section, and by means of actographs. General metabolism was evaluated through the analysis of oxygen consumption. Sex, size, and environmental factors proved to influence both the intensity and the timing of locom...

Summary Scorpion larvae spend their first larval stage settled on their mother's back. Isolated larvae can also survive, but their survival probability is lower than it is if they remain on the back of the mother. Experiments with tritiated water suggest that a water exchange must take place between mother and larvae.

Field observations and experiments were conducted on the intertidal gastropod Nerita textilis Gmelin along the Somalian coast to determine if its rhythmical mass homing includes the detection of durable substrate marking as well as short-term trail-following. The snails' first response to displacement is a zonal orientation compensating for the ver...