Deep-sea organisms are generally considered to be restricted to the great ocean depths, unable to enter shallower habitats except perhaps at the isothermic polar latitudes, due to physiological constraints, or more intense biotic interactions. Wood-boring bivalves of Xylophaga, however, are here shown to be exceptional. A clade, formally recognized by Turner in 2002, united by the derived characters of a complex mesoplax and a truncated excurrent siphon, papillose incurrent siphon with a longitudinal dorsal trough bordered by lappets, and often carrying white or glass-like granules, occurs at significantly shallower and warmer depths than do other species of the genus. Here, description of the new species X. multichela from 106 m depth off the Pacific coast of Guatemala illustrates the characters that unite the clade. Because wood-boring bivalves face intense competition and high levels of predation at depths of 2200 to 3250 m, they may not perceive biotic interactions at shallower depths to be dramatically more intense. In addition, members of this group are hypothesized to tolerate reduced oxygen availability, a requisite if animals are to occur in warm waters.

The annual commercial catch from the Southern Zone of the South Australian rock lobster (Jasus edwardsii) fishery is ~1900 tonnes, representing ~50% of total landings from south-east Australia. A single minimum legal size (MLS) of 98.5 mm carapace length (CL) exists across the entire zone. Fecundity (F), size at onset of maturity (SOM) and relative reproductive potential (RRP) of female rock lobsters were investigated in two major fishing regions, i.e. the North Southern Zone (NSZ) and South Southern Zone (SSZ) with a view to providing a basis for future fine-scale spatial management of the resource. F ranged from 45,292 to 466,800 eggs per female and increased proportionally with CL according to the relationship: F = 0.0584 × CL3.1642. F was significantly higher in the NSZ compared to the SSZ but was attributed to differences in lobster size between regions. There was no significant difference in the number of eggs · g−1 of egg mass between areas. SOM, estimated as the size at which 50% of females reached sexual maturity (L50) was higher in the NSZ (104.1 mm CL) compared to SSZ (92.3 mm CL). Approximately 20% of lobsters above the MLS in the commercial catch in the NSZ were under the L50 estimate. RRP, as a measure of egg production, was calculated for each size-class from the product of F, SOM and population length–frequency. The modal RRP size-classes in the NSZ were 117.5–122.5 mm CL, while in the SSZ it was 97.5–102.5 mm CL. Only 6% of RRP was contributed by female rock lobsters below the MLS in the NSZ, compared to 34% in the SSZ. Regional differences in SOM and RRP in the Southern Zone of South Australia suggest that different MLSs may be beneficial, particularly if the fishery is to be effectively managed at finer spatial scales.

Eudendrium moulouyensis is a zooxanthellate hydroid originally described from the Chafarinas Islands (Alboran Sea, south-western Mediterranean) in summer 1991. According to the original description, this species can be identified due to the occurrence of symbiotic zooxanthellae in the entire endodermal layer of the colony (gastrodermis and tentacle endodermis), a unique feature among the Mediterranean Eudendrium species. However, several aspects of its life cycle and the extent of its phenotypical variability are still unknown. Since winter 2004, colonies of E. moulouyensis were recorded throughout the year from 0.5 m to 30 m depth from the southern Adriatic Sea (Otranto Channel) and the Gibraltar Strait (Alboran Sea). Additional specimens were collected from the northern Adriatic (Vis, Croatia), Sicily Channel (Pantelleria and Lampedusa Islands), and western Sardinia (Costa Paradiso). These findings offered the opportunity to describe for the first time the full life cycle and to elucidate several biological aspects related to phenotypical variation of colony morphology, vertical zonation, seasonality, zooxanthellae–polyp relationship, and cnidome morphology and distribution. The number and morphology of male gonophores per reproductive polyp is described here for the first time, providing a useful taxonomic character to easily discriminate Myrionema amboinense from E. moulouyensis. From the available information, the occurrence of M. amboinense in the Mediterranean Sea should be regarded as doubtful, if they are not accompanied by observations of cnidome, male gonophores or distinctly separate tentacles whorls.

Beds of Modiolus modiolus, in areas of moderate to strong tidal currents, develop into reefs with a relief of wave like undulations 0.09–0.45 m in amplitude and length scales of 6–18 m. Cores taken by diver operated suction sampler were targeted at positions on the ridges and troughs of a reef, in the Irish Sea off north-west Wales, allowing the fauna to be compared between adjoining ridges and troughs. Sessile epifauna was mostly attached to the larger mussels clumped together on the ridges. The crevice fauna and infauna were also nearly three times more abundant on the ridges, but the lists of species were similar from the two sub-habitats. Species richness was higher on the ridges, however, diversity and evenness measures were similar for ridges and trough samples. The Modiolus sub-habitats were found to be distinct from other macrofaunal assemblages in the wider southern Irish Sea. Deposition of faecal pellets in the spatially complex habitat amongst the mussels provided conditions suitable for an infauna more typical of inshore muddy sands enriched by organic matter. The scale of the ridge and trough morphology may increase variability between replicates when grabs are used remotely to sample this type of biogenic feature.

The tanaidaceans are among the most conspicuous and ecologically relevant benthic microcrustaceans in the marine realm but there are only a few records of species of tanaids associated with other marine organisms. During a long-term survey on the biology and distribution of the Caribbean manatee Trichechus manatus manatus Linnaeus in Mexican waters, parasites and epibionts were collected from 47 individuals that were captured for tagging in two bay systems. Well-established epibiotic communities of the tanaidacean Hexapleomera robusta (Moore) were found on eight of these animals; this tanaid crustacean formed patches of tubes adhered to the skin surface. Patches were distributed in different parts of the body surface but mainly along the backbone depression, the caudal zone, and on the lateral margins; in some instances they were related to clusters of barnacles. Highly significant differences of infestation rates were revealed between Chetumal Bay and Ascensión Bay, the latter representing better conditions (high salinity and hydrodynamism) for tanaid invasion and settlement on the manatee. It is speculated that the tanaid is a commensal; no visible damage was found in the host and its presence was not related to skin lesions. The tanaid probably captures suspended particles as the manatee feeds. This is the first confirmed record of a symbiotic association involving a tanaid and the Caribbean manatee. The tanaid species recorded (H. robusta) and the harpacticoid copepod Balaenophilus manatorum (Ortíz, Lalana & Torres), have both been recorded also as epibionts of sea turtles. The tanaid has been known from sea turtles for some time, but the copepod was first recorded from a manatee and was subsequently found on sea turtles a few years later.

Hydroidolina is a group of hydrozoans that includes Anthoathecata, Leptothecata and Siphonophorae. Previous phylogenetic analyses show strong support for Hydroidolina monophyly, but the relationships between and within its subgroups remain uncertain. In an effort to further clarify hydroidolinan relationships, we performed phylogenetic analyses on 97 hydroidolinan taxa, using DNA sequences from partial mitochondrial 16S rDNA, nearly complete nuclear 18S rDNA and nearly complete nuclear 28S rDNA. Our findings are consistent with previous analyses that support monophyly of Siphonophorae and Leptothecata and do not support monophyly of Anthoathecata nor its component subgroups, Filifera and Capitata. Instead, within Anthoathecata, we find support for four separate filiferan clades and two separate capitate clades (Aplanulata and Capitata sensu stricto). Our data however, lack any substantive support for discerning relationships between these eight distinct hydroidolinan clades.

Previous studies identified the Amazon river dolphin (Inia geoffrensis) as the species frequently traded in public markets of Pará and Amazonas State (Brazil). In order to investigate the geographic origin and the taxonomic identification of these specimens we analysed 21 samples provided by residents of the city of Belém and vicinities (Pará State, Brazil), presumably purchased in the ‘Ver-o-Peso’ Market (Belém) or the Manaus Municipal Market. DNA was extracted from dehydrated genitalia or from genitalia conserved in alcohol and the cytochrome b gene was PCR-amplified. Phylogenetic analyses showed identical topologies in both MP and NJ trees, with Sotalia splitting into two groups, one clade comprising the estuarine dolphin (S. guianensis) and all eight haplotypes from market-samples and another one, comprising the tucuxi (S. fluviatilis) haplotypes from the GenBank. Our findings indicated that the marine species is under a stronger commercial pressure than the Amazonian river dolphin (I. geoffrensis) and the tucuxi (S. fluviatilis) in the region. Therefore population dynamic studies as well as population monitoring should be carried out in order to evaluate the effects of this commercial hunting on the species and its local populations. The marine dolphins have been incidentally captured in gill-nets in the region, suggesting that these activities must also be monitored at the same time that social programmes must be implemented in order to inform and clarify local community and people involved in fishery activity to avoid that more animals might be captured and killed.

The sulphonium compound dimethylsulphoniopropionate (DMSP) is commonly found in temperate green macroalgae. To examine taxonomic and regional and local geographical patterns of DMSP production in Australasian algae, I collected 30 species of green algae from 14 sites in three regions, eastern Australia, Tasmania, Australia, and the North Island of New Zealand. The distribution of DMSP content was similar to that seen from other areas of the world. DMSP was found in high concentrations in Ulva and Codium spp. It tended to be undetectable or in lower concentrations in other members of the orders Bryopsidales and Cladophorales. There was no evidence for differences in concentrations among the three regions in the genera Codium and Ulva; however, the invasive subspecies of Codium fragile, C. fragile ssp. tomentosoides, had significantly higher concentrations of DMSP than the non-invasive subspecies. The herbivorous sea slug Elysia maoria had whole body concentrations that were not significantly different from those of its host alga C. fragile ssp. tomentosoides. The distribution patterns of DMSP in Codium spp. do not support the hypothesis that DMSP is used as an antioxidant in this genus. Based on the data collected here and previous reports from the literature, I speculate that one function of DMSP in these algae may be to deter herbivores.

We evaluated sea urchin Strongylocentrotus droebachiensis predation on egg masses of the whelk Buccinum undatum. The urchin actively grazes on the egg masses, even as they are being deposited on the bottom. Whelks preferentially lay their egg masses on vertical areas where urchin densities are 4-fold less than on flat areas. This strategy is advantageous, as experimental trials showed that the loss in the mass of capsules was 4 fewer on walls than on flat areas. Nevertheless, a high proportion of egg masses on walls show damage from predation. Urchins provided with egg masses in the laboratory, ingested the capsules at a steady rate over a 9-d period (5 urchins ingested 2.8 g.d-1). Urchins provided agar discs that included a preferred alga and whelk capsule walls ingested the discs at a rate that was half that observed for discs that only included the alga. Discs that included the preferred alga and capsule contents were eaten at the same rate as discs that only included the alga. Thus, capsule walls, but not the capsule contents, provide a defence against urchin predation. Laying aggregate egg masses likely provides only a limited advantage, as the attachment surface does not increase with the number of egg masses deposited together, so the risk of detachment increases. Consideration of the interactions between urchins and whelks is important in managing the fisheries of the two species.

Little is known about spawning aggregations in subtidal populations of the nudibranch Onchidoris bilamellata. We provide photographic evidence of the spawning aggregations and associated spawning migrations or mass movements whose occurrence was debated.

Sexual maturation and spawning was followed in one and two year old rope cultured mussels (Mytilus edulis) from April to December. Development of gonad and storage tissue was followed using descriptive categories from histology, and development of total soft tissue was followed using meat yield and condition index.

Both age groups were mature both during spring and autumn and had similar patterns of spawning and maturation. April and May were characterized by scattered spawning activity and accumulation of storage reserves at the same time, resulting in relative constant condition indices during this period. This was followed by ripening of the gonads and an increase in condition index that culminated in a spawning in late June. Parts of the population then entered a resting phase, while a part of the population underwent new maturation towards an autumn spawning in September. In December all the mussels had started the winter maturation.

Condition index and meat yield were higher throughout the season in the one year old mussels. This was probably due to the sum of several factors, including differences in specific feeding rates and biomass density, rather than spawning.

The present study is the first to compare the reproductive patterns over time of one and two year old mussels with reliable age determination, and provide information that there are no obvious differences in neither timing of gonad development nor spawning patterns between the age-classes.

Egg masses, juveniles and adults of the gastropod Palio dubia were found in shallow rocky habitats of eastern Canada dominated by the bryozoan Eucratea loricata. Multiple-choice experiments and direct field observations revealed that P. dubia prefers to feed on E. loricata. Courtship, copulation and egg-laying as well as hatching of P. dubia were closely related to the lunar cycle. Reproduction was preceded by increased pairing and aggregative behaviour. The duration of embryonic development in the capsules was 10–15 d. After hatching, most veligers were retained within the bryozoan branches during their pelagic phase (1–3 d). In multiple-choice experiments, settlement occurred preferentially on the bryozoan E. loricata. In the absence of the preferred substratum, the larvae continued to swim and died after a period that never exceeded 8 d. Juveniles remained associated with the bryozoans on which they settled and reached the adult size in ~3 months.

The gametogenic cycle of the smooth clam Callista chione off the Arrábida region was studied throughout a 17-month period (from January 2004 to May 2005) using standard histological techniques, mean oocyte diameters and a condition index. This species showed a synchronism between sexes both in terms of gametogenic development and spawning. The results indicated that sex-ratio was not significantly different from parity. In January 2004, the gametogenic cycle had already begun and ended in late October 2004. Three spawning peaks were detected: January–March, April–May and August–October. No resting period was observed and a new gametogenic cycle began in early November, immediately after the spawning period. The analysis of the oocyte diameter enabled predicting the main spawning periods, which appear to be largely governed by seawater temperature. The condition index evolved according to the reproductive cycle of the species, with the highest values being observed prior to the main spawning periods. The size at first maturity estimated for C. chione was 50.81 mm.

Studies on differences in external morphology and pigmentation patterns were historically carried out using stranded individuals or opportunistic sightings; few studies have involved sampling systematically free-ranging individuals. In order to investigate and describe main pigmentation characteristics, outlining ‘typical’ regional pigmentations, this work analysed systematic photographic information taken on free-ranging striped dolphins, Stenella coeruleoalba. Photographs of dolphins in the Ligurian Sea were collected between May 2004 and December 2006. All individuals were described by the presence/absence of pigmentation variables and by differences in colour shades. The frequency of all the pigmentation variables analysed is stable in the population (10 ‘gene’ variables, 19 ‘allele’ variables), and remains similar between each different group of dolphins. But population presents widespread pigmentation variability between specimens, allowing identification even at single individual level. Cluster analysis also found that the majority of the pigmentations derive from two main colour patterns, called ‘mat’ and ‘pale’ patterns (fmat = 0.68; fpale = 0.12). The Bray–Curtis index showed a high variability of the intra-group pigmentation distance between groups. This resulted in a positive correlation between group size and ‘intra-group’ pigmentation distance: the distance increases rapidly up to a group size of 40 individuals. According to the results obtained, the striped dolphins seem to be concentrated in small groups in which there is a large phenotypic similarity among individuals. These small units could be associated between them to form temporary large groups observed only in pelagic waters.

A cold-shock technique was used to determine radula production rates for the chitons Acanthopleura hirtosa and Plaxiphora albida, and for the limpet Patelloida alticostata, which replaced their radular teeth at rates of 0.40, 0.36 and 0.51 rows d−1, respectively. These rates are far slower than those determined previously for non-iron-mineralizing molluscs, suggesting that the improved working life of the teeth afforded by iron-mineralization acts to significantly reduce replacement rates. In addition, inductively coupled plasma-atomic emission spectroscopy has been used to determine the quantity of iron and other elements comprising the radula of each species. These data, used in conjunction with the radula production rates, reveal that A. hirtosa, Plaxiphora albida and Patelloida alticostata have daily radula mineralization requirements for iron of 3.06, 4.12 and 0.55 μg, respectively. Such information is vital for continuing studies related to the cellular delivery of ions and subsequent biomineralization of the tooth cusps in chitons and limpets.

Pterobranchs are small marine filter feeders in the phylum Hemichordata. Their phylogenetic position and anatomical structure has resulted in pterobranchs featuring in many scenarios concerning the evolution of chordates. Despite this interest, the basic reproductive biology of pterobranchs is still poorly known. To address this issue, the reproductive season of Rhabdopleura compacta was investigated by collecting specimens in 2004–2007 from a population growing on disarticulated bivalve shells off the south coast of Devon, UK. I analysed reproductive status by categorizing shells according to the condition of the colonies growing on them. The frequency of shells having mature females was almost constant from spring to autumn among shells with active colonies. However, it was apparent that: (a) shells having mature females were more likely to be incubating embryos or larvae in June and July than other months; and (b) the production of embryos was high in June, and then decreased by July. Thus, despite the previous speculation that the species is capable of successful sexual reproduction throughout the year, the present study shows seasonality in reproduction of R. compacta, with at least a peak season during summer.

Most neogastropod species exhibit masculinization of the female when subject to tributyltin (TBT) pollution (a process known as ‘imposex’). To date, the dog-whelk Nucella lapillus is seemingly unique in having a genetic deficiency (termed Dumpton syndrome or DS) that disrupts the development of normal male sex organs, its presence being readily recognizable by the underdevelopment, or non-development (aphally), of the penis, and incomplete formation (non-closure) of the vas deferens, causing a split prostate. In highly contaminated conditions, female carriers of DS can be identified by a lesser degree of masculinization (notably aphally): they escape sterilization caused by the advanced stages of imposex. To date, DS has only been reported in areas with high TBT pollution which induces sterilization of normal females (i.e. non DS-affected females). DS is now, for the first time, observed at some locations where present TBT levels are low and some normal females lack penis development. In such conditions it is not possible to discriminate normal from DS-affected females using aphally. As DS-affected females must be discarded from the calculation of the imposex bioindicators to monitor TBT pollution, indirect tools such as molecular probe are now needed to further survey those areas where DS and TBT pollution may interact as, for example, in south-west Brittany.

Some of the most interesting and enigmatic cnidarians are classified within the hydrozoan subclass Trachylina. Despite being relatively depauperate in species richness, the clade contains four taxa typically accorded ordinal status: Actinulida, Limnomedusae, Narcomedusae and Trachymedusae. We bring molecular data (mitochondrial 16S and nuclear small and large subunit ribosomal genes) to bear on the question of phylogenetic relationships within Trachylina. Surprisingly, we find that a diminutive polyp form, Microhydrula limopsicola (classified within Limnomedusae) is actually a previously unknown life stage of a species of Stauromedusae. Our data confirm that the interstitial form Halammohydra sp. (Actinulida) is derived from holopelagic direct developing ancestors, likely within the trachymedusan family Rhopalonematidae. Trachymedusae is shown to be diphyletic, suggesting that the polyp stage has been lost independently at least two times within trachyline evolution. Narcomedusae is supported as a monophyletic group likely also arising from trachymedusan ancestors. Finally, some data, albeit limited, suggest that some trachyline species names refer to cryptic species that have yet to be sorted taxonomically.

The present study describes the species composition and vertical distribution of chitons in tide pools and on exposed rock areas of the intertidal zone of Samara, Guanacaste, Pacific Costa Rica. Nine different species of chitons were recorded, and their densities and sizes were determined using quadrate sampling. Physical (period of emersion, temperature and salinity range) and biotic (presence and diversity of food resources) factors were examined to assess their influence on distribution and abundance of each species. Ischnochiton dispar was the predominant species with densities of up to 200 ind m−2, representing 85.4% of all sampled individuals (N = 4193). The size of I. dispar was positively correlated with the size of the inhabited boulders. Two species (I. dispar and Stenoplax limaciformis) showed segregation in size: I. dispar being negatively and S. limaciformis positively correlated to the distance from the shore. Two of the nine species (Chiton stokesii and Acanthochitona hirundiniformis) occurred mainly on rocky areas outside the tide pools with variable amounts of exposure to air during each tidal cycle. In both species the tide pool specimens were significantly smaller than those collected in the rocky areas. Distribution of all other species was restricted to the tide pools and species had their peak abundance in the zones with more moderate conditions and a higher diversity of algae, resulting in the highest chiton diversity in these areas.

During biological sampling of hydrothermal vents on the East Pacific Rise, the manned submersible ‘Nautile’ caught the first female of the endemic cephalopod Vulcanoctopus hydrothermalis. The specimen caught at the vent site Gromit (21°33 66′S, 114°17 98′W at 2832 m depth) is described here in detail and an amended diagnosis of the species proposed. The external morphology, measurements and internal structure resemble that of males of this species. One of the most remarkable characters is the lack of spermathecae and the absence of apical filaments in the oocytes to provide a site for sperm storage. It is suggested that some species of the genera Benthoctopus and Bathypolypus would be the most suitable octopod ancestor of V. hydrothermalis.