Motile homes: a comparison of the spatial distribution of epibiont communities on Mediterranean sea turtles

Understanding the ecological roles performed by an individual species requires knowledge from a wide range of disciplines; here we analyze the epibiont–host relationship found in marine turtles. During the study we recorded five new species of sea turtle epibiont: Laomedea flexuosa, Caprella fretensis, Hyale nilssoni, Hyale schmidti, Parasinelobus chevreuxi; as part of a total of nine zoological epibionts present on 35 female green turtles (Chelonia mydas) and 100 loggerhead turtles (Caretta caretta) nesting in Cyprus. The two most commonly occurring epibionts were acorn barnacles Chelonibia testudinaria and Chelonibia caretta, with larger specimens of both species recorded on loggerhead turtles. We analyzed the spatial distribution of these two barnacle species upon the carapaces of their hosts. Specimens of C. testudinaria situated on the anterior half of the carapace were larger than those located at the posterior. A significantly larger proportion of loggerhead turtles (52.5%) hosted epibionts in comparison to green turtles (30.3%). All non-barnacle epibionts were associated with either posterior algal mats or carapace scars.     

Egestion of plant propagules by turtles in a small Massachusetts river

ABSTRACT

Evidence from flowing-water habitats has confirmed a role of turtles regarding the effective internal transport and viability of riparian plant seeds. We assessed potential propagule dispersal by Eastern painted turtles (Chrysemys picta) within a small river in Massachusetts and factors that may influence the diversity and abundance of egested propagules. From August–October 2015 and June–October 2016, we captured 69 turtles (28 male and 13 female), recorded standard measurements (sex, size, mass, BCI), and collected their faeces from which we isolated propagules. Propagules, mostly seeds, were observed in a small (28%) group of individuals. Overall, 4808 seeds of four taxa and 62 tubers were recovered. Most turtles (58%) defaecated propagules of just one taxon and number of seeds per turtle was highly variable (1–1506, 253.05 ± 414.55 seeds). Taxon richness, abundance, and Simpson Index of propagules varied significantly by sampling year. Sex-year interaction was also a significant predictor of propagule abundance. No turtle-specific features (sex or BCI) have any significant influence on any of the seeds egested. While our study suggests a minor role for C. picta as mobilisers of river plant propagules, these highly vagile animals may still create intermittent links between spatially isolated populations within and between waterbodies.     

Reproduction,planula development,and substratum selection in three species of Stylactaria (Cnidaria: Hydrozoa) from Hokkaido,Japan

Modes of reproduction, morphology and behaviour of planulae, and substratum specificity were studied and compared in three species of the hydrozoan genus Stylactaria from Hokkaido, S. conchicola, S. uchidai, and S. multigranosi. Observed differences in these attributes provide additional characters for discrimination of the three species. Stylactaria conchicola is oviparous, its planulae are sedentary, and its hydroid is substratum specific (living only on shells of the gastropod Homalopoma amussitatum). Stylactaria uchidai differs in being ovoviviparous, in having crawling planulae, and in being a substratum generalist. Stylactaria multigranosi is parthenogenetic, its planulae are sedentary, and it is substratum specific (occurring exclusively on the gastropod Nassarius multigranosus). Only female colonies of S. multigranosi are known, and gonophores of this species differ from those of S. conchicola and S. uchidai in being eumedusoid rather than styloid. Correlations were noted between attributes of the planula larva and substratum specificity in the three species. The cnidome differences between the species suggest that penetrant nematocysts are particularly important for sedentary planulae colonizing moving substrata. These characters are also considered useful in the taxonomy of species of Stylactaria. The phylogenetic significance of different gonophore types in the genus is considered.     

Octopus mimicking its follower reef fish

We describe a possible example of social mimicry between Octopus insularis and the small grouper Cephalopholis fulva, which frequently associate during foraging at Fernando de Noronha Archipelago, Brazil. The octopus, when swimming backwards, jet‐propelled, becomes similar in colour and shape to accompanying C. fulva individuals and is therefore less conspicuous within the fish group. We regard this as an instance of social mimicry, a form of protection against visually‐oriented predators in which different species similar in shape and colour mingle for the advantage of grouping. Even when swimming backwards alone, O. insularis may become similar to foraging C. fulva individuals, another putatively protective behaviour. We suggest that the feeding association commonly found between O. insularis and C. fulva minimized the evolutionary costs for the origin of mimicking by the octopus.     

Carapace epibionts of loggerhead turtles (Caretta caretta) nesting at Canaveral National Seashore,Florida

A survey of the epibionts inhabiting the carapace of loggerhead sea turtles Caretta caretta (Linnaeus) nesting on Canaveral National Seashore, Florida was conducted from 2003–2004. Epibionts were sampled and identified to the lowest taxonomic level possible. Eleven newly documented epibiont species were observed from 52 individual loggerheads. We present the first records of sea urchins as loggerhead epibionts. Data are presented on the behavioural, physical, and ecological characteristics of some of these newly documented species to understand better the relationship between loggerhead turtles and their epibiota.     

The carboniferous fossil lycopod Ulodendron landsburgii (Kidston) comb. nov.

Summary

A data gathering system controlled by microcomputer, recording swimming activity, is described. Prior to the breeding season, in a normal day and night regime, the delta prawn Palaemon longirostris shows a circadian swimming rhythm with peak activity at night. As the ovaries ripen and the prawns mate there is evidence of an additional tidal swimming rhythm. Females carrying eggs revert to nocturnal circadian swimming only. In ovigerous females the circadian swimming rhythm persists in continuous darkness with a free-running period of between 22 and 23 hours. The closely related and sympatric species Palaemonetes varians has similar patterns of swimming behaviour. It is suggested that the absence of newly hatched palaemonid larvae in the estuary is a result of the interaction of these adult swimming patterns with tidal flow and nocturnal hatching.     

Notes on astogeny of some Petraliellidae (Bryozoa) from Australia

Members of the bryozoan family Petraliellidae share the capacity to develop basal rhizoids, which anchor the unilaminar, semi-repent parts of the colonies above the substratum, and enable them to overgrow other, competing sessile forms. Little is known of the larval behaviour and settlement, or the early astogeny of species. Ancestrulate colonies of the Australian Tertiary lunulitiform species Smittia biincisa are referred to the genus Riscodopa, and together with Riscodopa paucipora sp. nov. are described and compared with the Recent species R. cotyla and R. parva from New Zealand, and with R. hyalina sp. nov. from New South Wales, Australia. All the Recent species are known to develop basal rhizoids, and an early astogeny similar to that of many other small, rooted bryozoans, comprising the post-metamorphosis development of a binary complex, including rhizoid and feeding elements, is inferred for Riscodopa. Observations on living Hippopetraliella magna from Queensland suggest that both the ancestrular morphology and early astogeny show a capacity for semi-repent growth, even though they do not include rhizoid development. Larvae metamorphose without direct attachment, and the ancestrula develops elongated, partially calcified supporting processes, which raise the early stages of growth above the substratum. A similar kind of ancestrula has been found in preserved specimens of Mucropetraliella ellerii.     

Tropical cyclones and reproductive ecology of Crocodylus acutus Cuvier, 1807 (Reptilia: Crocodilia: Crocodylidae) on a Caribbean atoll in Mexico

Crocodylus acutus, a coastal species nesting in sand beaches, could be affected by increasing tropical cyclone frequency. We studied key characteristics of C. acutus reproductive ecology on Banco Chinchorro atoll from 2006 to 2009, including the impact of two tropical cyclones. Hurricanes increased canopy openness causing earlier nesting the following year. Crocodiles nested at the beginning of the wet season with hatching in mid-wet season; this could represent a compromise between risking nest flooding and increasing freshwater availability for hatchlings. Tropical cyclones dramatically reduced nesting success by cooling and flooding clutches. Nursery sites were usually hypersaline, but heavy rainfall from tropical cyclones can likely benefit hatchling survival by decreasing salinity. While tropical cyclones have negative short-term impacts on crocodile nesting, they likely have an overall beneficial effect by creating and maintaining open sandy nesting areas used by C. acutus and they may explain its widespread distribution in Caribbean coastal areas.     

Freshwater sponges of the West Indies: Discovery of Spongillidae (Haplosclerida,Spongillina) from Cuba with biogeographic notes and a checklist for the Caribbean area

The paper reports the first finding of freshwater sponges from the Greater Antilles. Spongillidae belonging to four species of the genera Ephydatia, Anheteromeyenia, and Radiospongilla were found in a variety of freshwater habitats in western Cuba. Anheteromeyenia cheguevarai nov. sp. is described. Morphological traits of sponges from West Cuba were characterized by light microscopy and scanning electron microscopy and compared to the spongillofauna of the Nearctic and Neotropical regions and the pan‐Caribbean area. The specific richness and the discovery of a new species suggest a high diversity of the Antillean freshwater sponges although the investigated area of Cuba is relatively small.     

Digging with ‘hands’: observations of food capture in the flying gurnard Dactylopterus volitans (Linnaeus, 1758)

ABSTRACT

Videofilms of a foraging flying gurnard (Dactylopterus volitans) were collected at Itaipu, Niterói, RJ, Brazil. Analysis revealed details of the use of anterior parts of the pectoral fins which act as digging ‘hands’ to access infaunal prey items that are subsequently captured by oral suction feeding. Each pectoral fin has two distinct sections articulated separately on the pectoral girdle. The digging ‘anterior pectoral fin’ mainly consists of segmented and flexible fin rays but has an anterior robust unsegmented ray that provides an edge to the ‘hand’, allowing penetration of the substratum. The huge ‘posterior pectoral fins’ are supported by unsegmented rays. Most digging episodes involved one ‘hand’ and consisted of 1–7 cycles of movement with frequencies 1.15–3.74 cycles s^?1. During a cycle, the ‘hand’ is moved forwards and medially above the substratum, then is twisted medially and simultaneously depressed so that the anterior unsegmented ray impacts and enters the substratum. The hand is then drawn backwards and laterally to disturb the substratum. To prevent upward pitching of the head during digging, the ‘posterior pectoral fins’ are both moved anteriorly and laterally to shift the centre of gravity forwards while the caudal and ?second dorsal fins continue to provide propulsive force.     

A new species of Phyllodistomum (Digenea: Gorgoderidae) from Australian and New Zealand freshwater fishes with notes on the taxonomy of Phyllodistomum Braun, 1899

Phyllodistomum magnificum sp. nov., is described from the urinary bladder of Australian and New Zealand freshwater fish. Australian hosts were Anguilla reinhardtii, Tandanus tandanus, Hephaestus fuliginosus and Scortum hilli. New Zealand hosts were Anguilla australis and A. dieffenbachii. A presumed part of the life-cycle is described. Typical cystocercous cercariae are produced by sporocysts in the gills of a Pisidium species and are eaten by aquatic arthropods in which they encyst. The taxonomy of the genus Phyllodistomum is discussed and it is suggested that those species with cystocercous cercariae form a phylogenetic unit with Gorgodera, Gorgoderina, Progorgodera and Gorgotrema species.     

Novel records and observations of the barnacle Stephanolepas muricata (Cirripedia: Balanomorpha: Coronuloidea); including a case for chemical mediation in turtle and whale barnacles

We report new distribution and host records of the turtle barnacle Stephanolepas muricata Fischer. Ours is the first study to document this species' occurrence in Mexico and in the Atlantic Ocean (North Carolina, Georgia and Florida: USA). We also present the first record of S. muricata from olive ridley sea turtles, Lepidochelys olivacea (Eschscholtz). We discuss the physical and ecological characteristics associated with the specimens collected and present evidence suggesting the likelihood of chemical mediation between embedding coronuloid barnacles like S. muricata and host turtles. We provide the first data on the diet and fecundity of S. muricata.     

Bionomics of the myrmecophilous oribatid mite Protoribates myrmecophilus (Acari: Oribatida) in the Oriental tropics

Behavioural interactions between the myrmecophilous oribatid mite Protoribates myrmecophilus and the host ant Myrmecina spp. are described and compared to those of Aribates javensis which shows a very specialized myrmecophily. The behaviour of P. myrmecophilous is similar to free-living oribatids: they can walk by themselves and can survive without ant attendance. In the ant nests, the mites are sometimes cared for by ants and they are brought by ants into a new nest site. Protoribates myrmecophilus is eaten by non-host species of Myrmecina. Protoribates myrmecophilus is a less specialized myrmecophilous oribatid species.     

Repeated sampling adds to the genetic diversity of Lepidochelys olivacea (Eschscholtz 1829) olive ridley sea turtle

ABSTRACT

First sampled in the late 1990s, Campamento Tortuguero La Gloria, in Jalisco, Mexico, was resampled for olive ridley sea turtle (Lepidochyles olivacea Eschscholtz) diversity 10 years later. A comparison with all previously reported mitochondrial sequences revealed that these new samples added to the known genetic diversity for this species, and revealed unexpectedly high genetic diversity among turtles nesting on this beach. The results highlight the importance of systematic resampling in known nesting rookeries to verify the genetic diversity of study populations. Three new olive ridley haplotypes are reported, all more closely related to Baja Californian haplotypes than to Australian haplotypes. Significant genetic divergence is reported within populations, within ocean basins (Atlantic, Pacific, Indian and Indo-Pacific), and between ocean basins. Furthermore, this is the first study that integrates satellite tagging data to demonstrate diverse post-nesting migration patterns of turtles with identical haplotypes, and it demonstrates flexibility in post-nesting migratory behaviour for olive ridley sea turtles of the same genetic provenance.     

Observations on the locomotion and buoyancy of Phronima sedentaria (Forskål, 1775) (Crustacea: Amphipoda: Hyperiidea)

The buoyancy and locomotion of the hyperiid amphipod Phronima sedentaria (which lives in barrels constructed from the tissues of gelatinous animals) was studied. The amphipods were much denser than sea water. Barrels were slightly denser than sea water and had six times the mass of the amphipods living within them. Phronima sedentaria swims much more quickly (by a factor of about 3–4) when swimming without its gelatinous barrel. The barrel is asymmetrical with one aperture (entrance) having about three times the area of that of the other (exit). All sustained swimming was accomplished with the larger barrel aperture directed forwards and the significance of this is discussed. Water flow around the barrel and much of the flow through the barrel was laminar; turbulence was limited to the posterior third of the interior of the barrel and was associated with the beating of the pleopods that provide both propulsion and the respiratory current.     

A checklist of suctorian epibiont ciliates (Ciliophora) found on meiobenthic marine nematodes

ABSTRACT

A compilation of the ciliated suctorian species found on marine meiobenthic nematodes as epibiont has been carried out based on published records. It included the taxonomic position of each species of ciliate epibiont, the species of basibiont nematodes, the geographic zones where they have been found and the different records of these species together with the corresponding bibliographic references. Altogether 12 suctorian species were listed. Among registered suctorian species, Thecacineta oregonensis, T. urceolata, Trematosoma rotunda, Loricophrya bosporica, L. mediterranea, L. scanica, L. sivertseni, L. spitinae and L. stresemanni are likely specific to nematodes. The species as Thecacineta calix and Limnoricus ceter were found on a variety of hosts. Representatives of the genus Thecacineta reproduce by vermigemmic budding, swarmers of which are unable to swim, and often attached close to the cloaca of the nematodes. Any regularity in localization were not observed in the representatives of genera Trematosoma and Loricophrya, which form ciliary, swimming swarmers.     

Exploitation of Cornucopina tuba (Bryozoa: Cheilostomata) by Aetea curta (Bryozoa: Cheilostomata)

Distal portions of zooids of uniserial, encrusting Aetea colonies curve abruptly away from the encrusted substratum. This characteristic, plus highly directional growth capability, enabled A. curta infesting an erect Cornucopina tuba colony to position its feeding structures consistently above the host colony, perhaps as a rheophilic growth response of individual zooids to feeding currents set up by the host.