Cetaceans in the eastern South Atlantic Ocean are poorly studied. We present results from a 2 week ship-based survey from Cape Town to Vema Seamount (980 km to the west) during October–November 2019, including visual and towed-hydrophone observations from the vessel, and 10 days of acoustic monitoring on the seamount. Fifty-two hours of visual surveys resulted in 39 encounters of whale groups including seven of humpback, six of fin and one sei whale, as well as four unidentified baleen whales, 18 unidentified balaenopterid whales and four unidentified odontocetes. Two humpback whales at the seamount were engaged in possible feeding behaviour. A large aggregation of mostly fin whales was observed near the continental shelf edge (22 encounters over a 70 × 50 km2 area, six fin, one sei whale, 15 not confirmed to species), an historic whaling ground for both fin and sei whales. Towed-hydrophone data (78.7 h) detected five groups of sperm whales, 45 of delphinids, one beaked whale and no Kogiids. Acoustic data from the seamount detected calls from several baleen whale species including humpback whale non-song calls, Antarctic minke ‘bioduck’ calls, sei whale down-sweep calls and a likely Bryde's whale call. Two call types could not be assigned to species, including the most detected – a simple frequency-modulated call with peak power around 130 Hz. This study contributes to an improved understanding of cetacean occurrence in the eastern South Atlantic Ocean and highlights the need for more research to improve identification of cetacean vocalizations in the region.

‘Mindreading’ or theory of mind (ToM) refers to the capacity to attribute mental states to others. This ability is regarded as a critical component of what has, to date, exclusively characterized the advanced social cognition displayed by humans. The false belief task is a key test for ToM in different animal species. On a standard non-verbal false belief task, humans pass from age 4, whereas non-human primates consistently fail. Neuroanatomical and behavioural evidence for dolphins, however, indicates that they are capable of passing ToM tasks. The current paper represents a synthesis of the relevant dolphin research on neocortical evolution and non-invasive behavioural tests of precursors for ToM and the attribution of beliefs. The success of dolphins on attribution of belief tasks, in the absence of learning or cueing, indicates that they are capable of ‘mindreading’. What are the implications of animal ‘mindreading’? ToM tasks probe for reflexive consciousness and, by this criterion, dolphins may display reflexive consciousness. The implication of this conclusion is that future behavioural studies of social cognition will have considerable ethical and legal implications for animal welfare.

Dolphins in captivity have to cope with severe changes in their environment. So far, there are few studies on the welfare of these animals under these conditions. The aim of the present study was to find if cortisol was present in the saliva of dolphins and to explore the possibility of performing serial, non-invasive cortisol assays in captive dolphins. Saliva was collected non-invasively during a month from four dolphins that had responded to previous training, in order to provide saliva samples, in two aquaria in Mexico City. In addition, serum and saliva time-matched samples were obtained in an aquarium in Nuevo Vallarta, Mexico. Cortisol concentrations in saliva and blood were measured by radioimmunoanalysis (RIA). Results show for the first time that measurable quantities of cortisol are secreted within the saliva of dolphins. Salivary cortisol measurements could be a useful tool for carrying out long-term cortisol sampling. It is far less invasive than blood-sampling and could be used, in conjunction with behavioural observations, to monitor the welfare of captive dolphins, non-invasively.

Awareness of the self and awareness of others are difficult faculties to define. Part of the problem lies in the wide range of abilities that involve various aspects of awareness. Some of the most commonly studied abilities focus on the self-awareness of the individual. These abilities range from the capacity to distinguish self from non-self to the competency to reflect on one's past, present or future condition. Another set of abilities that is relevant to the study of awareness involves the interactions of individuals, and includes behaviours such as deception and empathy. We explore the possibility that species other than humans engage in deception and empathy, and consider the implications of such behaviours for self-awareness and other-awareness in these species. Although examples from a variety of species are provided, many examples come from dolphins and whales. This reflects both the authors’ interest in these animals and the possibility that large-brained creatures are more likely to engage in deliberate deception and/or true empathy.

This study aimed to describe the ethnoecology of the franciscana (Pontoporia blainvillei) using the traditional knowledge of artisanal fishermen in the villages of Peças Island (VPI) and Superagui Island (VSI) in the World Heritage listed Paranaguá Estuarine Complex, Brazil. Between March and September 2012, 90 fishermen were interviewed (VPI – 40; VSI – 50) using a semi-structured questionnaire. Using Fuzzy logic (MATLAB 7.6) it was verified the species is easily recognized by body size, colour and occurrence area (VPI – 87.5%; VSI – 38.0%). Fishermen most frequently identified adults and young franciscanas in groups of two to five individuals (VPI – 40.0%; VSI – 58.0%). Adults were sighted throughout the year, while the young were restricted to summer and winter. Five common behavioural ethno categories were described: ‘eat’ (VPI – N = 15; VSI – N = 1); ‘float/sink/dive’ (VPI – N = 34; VSI – N = 12); ‘breathe’ (VPI – N = 11; VSI – N = 5); ‘mothers surrounding the shoal, play caught up and the youth captures’ (suggesting care parental related with feeding of infant) (VPI – N = 1; VSI – N = 2); and ‘to play’ (VPI – N = 6; VSI – N = 1). The information from the fishermen highlights the use of the area by franciscana for feeding and reproduction and these data are comparable with the literature. These results extend the knowledge about the species in an area of ecological interest and the traditional knowledge, but also illustrate the benefits of engaging fishermen to promote collaboration in scientific and management processes.

This article offers a close reading of Pindar's lacunose fr. 140b S.-M. and explores the evidence it includes for Pindar's contributions to contemporary debates and polemics in late sixth- and early fifth-century musical culture concerning, among other things, harmonics, tonal ranges, instrumentation and the boundaries between different genres. By reading the contents of the fragment against the backdrop of other works from the period that similarly engage in these issues and the later revisionary accounts of the questions first raised by the author-musicians of the early classical age, I show how the diction, imagery and structure of the work are designed to position Pindar as one among the current choral innovators. In the discussion's final part, I address the question of the genre to which the piece belongs and propose some fresh ways of addressing this still outstanding matter. At several points, the article also considers some relevant visual evidence.

Age and length data of 291 franciscana dolphins (Pontoporia blainvillei) incidentally captured on the coast of Rio Grande do Sul State (RS), southern Brazil, were used to fit growth curves using Gompertz and Von Bertalanffy growth models. A small sample of franciscanas (N = 35) from Buenos Aires Province (BA), Argentina, were used to see if there are apparent growth differences between the populations. Male and female franciscana samples from both areas were primarily (78–85%) <4 years of age. The Von Bertalanffy growth model with a data set that excluded animals <1 year of age provided the best fit to data. Based on this model, dolphins from the RS population reached asymptotic length at 136.0 cm and 158.4 cm, for males and females, respectively. No remarkable differences were observed in the growth trajectories of males and females between the RS and BA populations.

Australodelphis mirus (Delphinidae n. gen., n. sp) is a small extinct Early Pliocene dolphin known from five individuals from shallow-water strata of the Sørsdal Formation, Vestfold Hills, East Antarctica. Australodelphis mirus is the first higher vertebrate named from the Oligocene-Pleistocene interval on land in Antarctica, and is the first cetacean fossil from the polar margin of circum-Antarctic Southern Ocean that postdates the break-up of Gondwana. The dolphin is convergent in skull form with some living beaked whales (Mesoplodon spp.; Family Ziphiidae) in its long, narrow and toothless upper jaw and face, but skull suture patterns, basicranial sinuses, and ear-bones indicate close relationship with living long-beaked dolphins (Delphinidae). Australodelphis mirus perhaps was a suction-feeding squid-eater which occupied quiet near-shore shelf waters influenced by glaciers but probably lacking major sea-ice. Possible ecological equivalents of A. mirus (small ziphiids, long-beaked dolphins) do not occupy Antarctic waters today, perhaps excluded by cold conditions and/or sea-ice cover. Earlier Pliocene cetaceans worldwide reveal significant extinct and sometimes bizarre taxa, and extant families with ranges quite different from today, pointing to climate-related changes in cetacean ecology in the last 2–3 million years.

A comparative study was made on one Mysticete (the fin whale, Balaenoptera physalus) and one Odontocete species (the striped dolphin, Stenella coeruleoalba) by measuring several morphological characteristics seen in cross sections of the optic nerve. We found that the two cetacean nerves share a number of specializations that distinguish them from the optic nerve of terrestrial mammals. Fiber density is approximately two-fold lower than in land mammals. A corresponding increase in the cross-sectional area occupied by astrocytes is observed. A population of “giant” (up to 15 μm in diameter) optic axons is present in both the B. physalus and the S. coeruleoalba nerve. It is argued that these features probably reflect common adaptations to the constraints imposed by the aquatic environment. “Giant” optic axons might ensure short-latency detection of preys and other targets during navigation while the increased astroglial content might be related to the maintenance of neuronal function during periods of anaerobic metabolism under water.

Each summer the presence of large concentrations of bait fish in the area of the central Azores Islands gives rise to mixed-species feeding aggregations usually at dawn and dusk. The encircling of prey initiated by common dolphins (Delphinus delphis), often mixed with spotted dolphins (Stenella frontalis), results in the formation of a compact ‘ball’ of several thousands prey fish close to the surface. Other dolphins, in particular the bottlenose (Tursiops truncatus), also eat the prey fish, whose high concentration makes them easy to capture. Large tunas (Thunnus thynnus, Thunnus albacares) sometimes participate in the phenomenon. Seabirds (mainly cory’s sheawaters, Calonectris diomedea borealis) are always present throughout the few minutes during which the entire collective food hunt takes place. A model of the phenomenon, based on 15 observations, is proposed. It comprises 4 stages: a preparation phase, an intensification phase, a mature phase, and a dispersion phase. These observations allow a better understanding of the tuna-dolphin aggregation process. They show that it is the tunas that generate and beneficiate from the aggregation with dolphins, rather than the contrary.

The helminth parasites from more than 300 cetaceans stranded on the coast of England and Wales during the period 1990-1994 were identified, this being the largest organized survey of cetacean parasites yet undertaken. Thirteen species of cetaceans were examined, although the majority were common (harbour) porpoises Phocoena phocoena (n=173) and common dolphins Delphinus delphis (n=101). The parasites found included 11 species of nematode (Anisakis simplex, Pseudalius inflexus, Torynurus convolutus, Stenurus globicephalae, S. minor, Halocercus delphini, H. invaginatus, H. lagenorhynchi, H. taurica, Crassicauda boopis, Crassicauda sp.), five cestodes (Diphyllobothrium polyrugosum, D. stemmacephalum, Phyllobothrium delphini, Monorygma grimaldii, Tetrabothrius sp.), five digeneans (Campula oblonga, Oschmarinella albamarina, O. rochebruni, Lecithodesmus palliatus, Pholeter gastrophilus) and two acanthocephalans (Bolbosoma capitatum, B. physeteris). The results of this survey are tabulated and each helminth species is discussed in terms of its biology and pathogenicity.

To assess the dolphin's capacity for color vision and determine the absorption maxima of the dolphin visual pigments, we have cloned and expressed the dolphin opsin genes. On the basis of sequence homology with other mammalian opsins, a dolphin rod and long-wavelength sensitive (LWS) cone opsin cDNAs were identified. Both dolphin opsin cDNAs were expressed in mammalian COS-7 cells. The resulting proteins were reconstituted with the chromophore 11-cis-retinal resulting in functional pigments with absorption maxima (λmax) of 488 and 524 nm for the rod and cone pigments respectively. These λmax values are considerably blue shifted compared to those of many terrestrial mammals. Although the dolphin possesses a gene homologous to other mammalian short-wavelength sensitive (SWS) opsins, it is not expressed in vivo and has accumulated a number of deletions, including a frame-shift mutation at nucleotide position 31. The dolphin therefore lacks the common dichromatic form of color vision typical of most terrestrial mammals.