African Slope Research Articles

Spiny Mice Modulate Eumelanin to Pheomelanin Ratio to Achieve Cryptic Coloration in “Evolution Canyon,” Israel

BackgroundCoat coloration in mammals is an explicit adaptation through natural selection. Camouflaging with the environment is the foremost evolutionary drive in explaining overall coloration. Decades of enquiries on this topic have been limited to repetitive coat color measurements to correlate the morphs with background/habitat blending. This led to an overwhelming endorsement of concealing coloration as a local phenotypic adaptation in animals, primarily rodents to evade predators. However, most such studies overlooked how rodents actually achieve such cryptic coloration. Cryptic coloration could be attained only through optimization between the yellow- to brown-colored “pheomelanin” and gray to black-colored “eumelanin” in the hairs. However, no study has explored this conjecture yet. “Evolution Canyon” (EC) in Israel is a natural microscale laboratory where the relationship between organism and environment can be explored. EC is comprised of an “African” slope (AS), which exhibits a yellow-brownish background habitat, and a “European” slope (ES), exhibiting a dark grayish habitat; both slopes harbor spiny mice (Acomys cahirinus). Here, we examine how hair melanin content of spiny mice living in the opposing slopes of EC evolves toward blending with their respective background habitat.Methodology/Principal FindingsWe measured hair-melanin (both eumelanin and pheomelanin) contents of 30 spiny mice from the EC using high-performance liquid chromatography (HPLC) that detects specific degradation products of eumelanin and pheomelanin. The melanin pattern of A. cahirinus approximates the background color of the slope on which they dwell. Pheomelanin is slightly (insignificantly) higher in individuals found on the AS to match the brownish background, whereas individuals of the ES had significantly greater eumelanin content to mimic the dark grayish background. This is further substantiated by a significantly higher eumelanin and pheomelanin ratio on the ES than on the AS.Conclusion/SignificanceIt appears that rodents adaptively modulate eumelanin and pheomelanin contents to achieve cryptic coloration in contrasting habitats even at a microscale.

Northward Penetration of Antarctic Intermediate Water off Northwest Africa

Abstract In this article, historical and climatological datasets are used to investigate the seasonal northward propagation of Antarctic Intermediate Waters (AAIW) along the eastern margin of the North Atlantic subtropical gyre. A cluster analysis for data north of 26°N shows the presence of a substantial number of hydrographic stations with AAIW characteristics that stretch northeast along the African slope. This water mass extends north during fall, as shown both through the comparison of actual and climatological data, and by applying a mixing analysis to normal-to-shore seasonal sections at both 28.5° and 32°N. The mixing analysis is further used with several fall cruises between 32° and 36°N, and shows that at these latitudes the core of AAIW propagates along the 27.5 isoneutral with contributions that reach as much as 50% at 32.5°N. An idealized Sverdrup-type model is used in combination with climatological hydrographic and wind data to examine what forces this eastern boundary propagation. It is found that column stretching, initiated in the tropical North Atlantic, is the dominant term in the vorticity balance of the AAIW stratum, capable of sustaining a winter–spring–summer northward transport of about 3–4 Sv (1 Sv ≡ 106 m3 s−1) that reaches as far north as the Canary Archipelago (28°N). In fall, this transport may continue beyond 28°N, sustained by a near-slope meridional stretching of this water stratum. AAIW probably fades away in the northeastern region as the result of several processes, specially enhanced double diffusion with surrounding waters and interaction with Mediterranean water lenses.

Adaptive Melanin Response of the Soil Fungus Aspergillus niger to UV Radiation Stress at “Evolution Canyon”, Mount Carmel, Israel

BackgroundAdaptation is an evolutionary process in which traits in a population are tailored by natural selection to better meet the challenges presented by the local environment. The major discussion relating to natural selection concerns the portraying of the cause and effect relationship between a presumably adaptive trait and selection agents generating it. Therefore, it is necessary to identify trait(s) that evolve in direct response to selection, enhancing the organism's fitness. “Evolution Canyon” (EC) in Israel mirrors a microcosmic evolutionary system across life and is ideal to study natural selection and local adaptation under sharply, microclimatically divergent environments. The south-facing, tropical, sunny and xeric “African” slope (AS) receives 200%–800% higher solar radiation than the north-facing, temperate, shady and mesic “European” slope (ES), 200 meters apart. Thus, solar ultraviolet radiation (UVR) is a major selection agent in EC influencing the organism-environment interaction. Melanin is a trait postulated to have evolved for UV-screening in microorganisms. Here we investigate the cause and effect relationship between differential UVR on the opposing slopes of EC and the conidial melanin concentration of the filamentous soil fungus Aspergillus niger. We test the working hypothesis that the AS strains exhibit higher melanin content than strains from the ES resulting in higher UV resistance.Methodology/Principal FindingsWe measured conidial melanin concentration of 80 strains from the EC using a spectrophotometer. The results indicated that mean conidial melanin concentration of AS strains were threefold higher than ES strains and the former resisted UVA irradiation better than the latter. Comparisons of melanin in the conidia of A. niger strains from sunny and shady microniches on the predominantly sunny AS and predominantly shady ES indicated that shady conditions on the AS have no influence on the selection on melanin; in contrast, the sunny strains from the ES displayed higher melanin concentrations.Conclusions/SignificanceWe conclude that melanin in A. niger is an adaptive trait against UVR generated by natural selection.

Mass fluxes in the Canary Basin

Ocean studies in the 1970s provided an improved knowledge of the coastal upwelling region off NW Africa while in the 1980s and 1990s they led to a good description of the open ocean flow patterns in the Canary Basin. It was not until the late 1990s that major research addressed the open-coastal ocean coupled response. Here we examine the mean and seasonal circulation patterns in the Canary Basin with data from four hydrographic cruises carried out in the region between Cape Ghir, Madeira Island, and the Canary Islands. We apply an inverse box model to an ocean divided into 14 layers, with several layers representing each water mass or stratum, to obtain mass fluxes consistent with the thermal wind equation. An optimum flow description is obtained using conservation of mass, salt and heat anomaly, biologically corrected oxygen, and silicate, and allowing for Ekman transport in the surface layer and dianeutral mixing between adjacent layers. The deep waters show no predominant flow direction while the intermediate waters display localized southward flowing Mediterranean Water far from shore, and northward flowing Antarctic Intermediate Water near the continental slope, specially in the passage between the eastern Canary Islands and the African slope. The mean upper-thermocline Canary Current, composed of North Atlantic Central Water, flows south with an open-ocean branch transporting about 3 ± 1 Sv (1 Sv = 10 6 m 3 s −1 ≅ 10 9 kg s −1), and an upwelling-related branch near the continental slope carrying 1 ± 0.3 Sv. The seasonal transport by the open-ocean branch intensifies and moves offshore from spring to fall (2.8 ± 1.2 Sv in spring, 2.9 ± 1.1 Sv in summer, and 4.5 ± 1.2 Sv in fall), while it carries its lowest southward mass flux in winter (1.7 ± 1.0 Sv), possibly as a result of a migration offshore the sampled region. Upwelling-related southward flow is present in spring and summer (1.9 ± 0.1 Sv and 2.4 ± 0.1 Sv, respectively) while in fall and winter it merges with the offshore southward branch. This westward migration allows a northward mass flux between the Canary Islands and the African coast (1.8 ± 0.1 Sv), that by winter reaches Cape Ghir (0.5 ± 0.2 Sv). Seasonal air–sea heat fluxes fit well with the climatological values. The net phosphate transport in the surface layer indicates that primary production was negligible in this region during January 1997 and April 1998, though in this last month production was probably starting as a result of significant nutrient supply.

"Evolution Canyon": A Microcosm of Life's Evolution Focusing on Adaptation and Speciation

Local microcosmic natural laboratories, dubbed "Evolution Canyon" (EC) models, reinforce studies of regional and global macrocosmic ecological theaters across life and unravelevolution in action.The EC model laboratories permit genomic, proteomic, and phenomic studies highlighting speciation and adaptation at a microscale. Critical transplant experiment tests can evaluate interslope differential fitness. Novel techniques of genetic mapping, sequence nucleotide polymorphisms (SNPs), and wide genome coding and noncoding expressions can unravel evolutionary dynamics. Finally, fundamental problems such as stress effects on nonrandom mutations, lateral transfers, splicing variations, sex, and social evolutions, and adaptive strategies of prokaryotes and eukaryotes are testable. We are studying four "Evolution Canyons" (EC I-IV) in the Carmel, Galilee, Negev, and Golan mountains. We've identified 2,500 species in EC I (Carmel) from bacteria to mammals in an area of 7,000 m. Higher terrestrial species richness was found on the more stressful tropical "African" slope (AS). Aquatic species richness was higher on the milder, temperate "European" slope (ES). In soil fungi we found interslope local and regional adaptive divergence in sex, melanism, and conidia. In nine out of 14 (64%) model organisms across life we identified largely higher genetic polymorphisms on the more stressful "African" slope. In some model species we found higher mutation rates, gene conversion, recombination, DNA repair, and larger genome size as well as interslope divergent micro-satellites, molecular polymorphisms, retrotransposons, and wide-genome gene expression on the more stressful AS. Remarkably, interslope incipient sympatric speciation was found across life. The "Evolution Canyon" model represents the Israeli ecological equivalent of the Galapagos Islands. Micro-climatic selection overrides drift and drives both interslope adaptive radiation and incipient sympatric speciation. The EC model could potentially highlight many mysteries of evolutionary biology.

Adaptive spatiotemporal distribution of soil microfungi in ‘Evolution Canyon’ II, Lower Nahal Keziv, western Upper Galilee, Israel

We describe and interpret spatiotemporal micromycete community structure and adaptive complexes in contrasting xeric and mesic microclimates in the soils of ‘Evolution Canyon’ II, Lower Nahal Keziv, western Upper Galilee, Israel. A total of 192 species from 60 genera belonging to Zygomycota (nine species), Ascomycota (13 species), and mitosporic fungi (170 species) were isolated. The fungal communities on the south-facing, xeric, ‘African’ slope (AS) demonstrated significantly greater diversity than on the north-facing, mesic, ‘European’ slope (ES) and the valley bottom (VB). Seasonally, winter slope communities were less heterogeneous. Forest localities on the ES and the VB in all seasons and the shady localities on the AS in the winter were overwhelmingly dominated by mesophilic Penicillium species. The sunny locality on the AS was characterized by a dominance of melanin-containing micromycetes that was most pronounced in the summer and by high occurrence and abundance of thermotolerant and thermophilic Aspergillus and Fusarium species. Ascomycetes and zygomycetes were the minor components in all local mycobiota studied; sexual ascomycetes, being stress-selected fungi, were more than ten times more abundant in the soil of the AS than in that of the ES, with the peak of abundance in the sunny summer community. The results demonstrated a microscale adaptive spatiotemporal inter- and intraslope divergence in soil mycobiota structure. Microclimatic natural selection appears to be the major factor affecting soil fungus diversity patterns. © 2003 The Linnean Society of London. Biological Journal of the Linnean Society , 2003, 78, 527–539.

Yeast interslope divergence in soils and plants of "Evolution Canyon", Lower Nahal Oren, Mount Carmel, Israel

This is the first report on yeast species diversity recorded in Israel at the Evolution Canyon microsite in Mount Carmel, Israel, subdivided into a xeric, African;, savanna-like south-facing slope, and a mesic, forested, European north-facing slope. A total of 25 species belonging to 14 genera were recorded--19 species of soil yeasts from 11 genera and 14 species of plant yeasts from 10 genera, including 8 species and 7 genera common to plants and soil. The total number, as well as the total frequency of occurrence of yeast species, was higher on the European slope than on the African slope in samples from both plants and soil. The basidiomycetous yeast species, Cryptococcus magnus, the ascomycetous species, Debaryomyces hansenii var. hansenii, with its anamorph, Candida famata, and the black yeast, Aureobasidium pullulans, were dominant on both slopes and in both plant and soil samples.

Reproductive biology of porcellanasterid asteroids from three abyssal sites in the northeast Atlantic with contrasting food input

The reproductive biology of the abyssal asteroids Hyphalaster inermis, Styracaster chuni, and S. horridus from the Porcupine Abyssal Plain (PAP), the Madeira Abyssal Plain (MAP), and the northwest African slope (NWA) is described and compared. The most northern location (PAP) is subjected to a strong seasonal input of aggregated phytodetritus to the seabed. The site at MAP does not receive a significant signal of phytodetritus but has been affected recently (ca. 1,000 years ago) by a relatively organic-rich turbidite. The site in the NWA is affected by a strong upwelling regime, which provides the seabed with important inputs of surface-derived organic matter. The gametogenic processes were similar in all three species at the three locations. Oogenesis was asynchronous. The previtellogenic oocytes grow to a size of ~150–200 µm before undergoing vitellogenesis. Most of the volume of the ovary was occupied by large vitellogenic oocytes of 300–500 µm in diameter. The maximum oocyte size was ~650 µm. The males had a continuous supply of spermatozoa densely packed in the lumen of the testes. There were no seasonal variations in gonad index (GI), pyloric caecum index (PCI), and fecundity for any of the species. The GI of H. inermis was similar between locations, indicating a constant allocation of energy to reproduction. The mean GI of S. horridus differed between locations, but there was no clear pattern. Size at maturity and average adult size were larger in the specimens from PAP and NWA than in the specimens from MAP. Fecundity was significantly higher in the specimens from PAP and NWA than in the specimens from MAP. The results are discussed in relation to phylogenetic constraints on gametogenesis and the effects of food quantity and quality on reproductive output.

The Eastern Boundary Current system between the Canary Islands and the African Coast

To study the EasternBoundaryCurrentsystem off Northwest Africa in detail several CTD/ADCP-sections and long-term mooring work were carried out in the channel between Lanzarote and Africa. The observations are compared with a fine-resolution model, which was developed in the framework of the CANIGO project. The water masses, which are observed in this area, are characterised and classified in density ranges. The current field shows a high spatial and temporal variability with maximum velocities of about 35 cm/s. Seasonal means as well as currents averaged across the channel are only a few cm/s. In the surface water a steady southward flow in the middle of the channel indicates the CanaryCurrent in this area. During fall a strong northward current is observed close to the African shelf. Though the CanaryCurrent strengthens during summer and fall due to an increase of the trade winds, the transport in the channel decreases or turns northward during that time due to the enhanced poleward current at the eastern side. A northward undercurrent with a mean velocity of +2.3 cm/s is observed at the African slope in 950 m depth. The poleward transport of AAIW increases during fall and a strong influence of relatively fresh AAIW is observed during that time. Most of the observations fit well to the results of the CANIGO model, but the occurrence of MW at the bottom of the channel and the corresponding southward flow cannot be resolved by the model.

Spatial variations in nutrient utilization, production and diagenesis in the sediments of a coastal upwelling regime (NW Africa): Implications for the paleoceanographic record

A biogeochemical study of recent (multicores) sediments of the northwest African slope was undertaken to understand how the sediment composition varies with respect to the location of core sites relative to the centers of coastal upwelling, and how this has affected the palaeoceanographic record. Sedimentary organic carbon contents are inversely correlated with the nitrogen isotopic composition (δ 15 N), high C organic concentrations and low δ 15 N occurring at proximal (shallow) sites and the opposite at distal (deep) ones. These spatial differences are interpreted to result from higher relative nutrient utilization and a decrease in production as waters are advected offshore from the zone of upwelling. Highest C organic contents also correlate positively with highest concentrations of redox-sensitive elements (U, Mo and S) that are fixed diagenetically in the sediments. These results suggest that the sedimentary regime at a fixed position depends on the spatial location of the productive areas relatively to a given core site. Downcore records of Zr/Al, Ti/Al, mean grain size of the terrigenous fraction, δ 15 N, C organic , biogenic Ba, U, Mo and sulfur at a single site on the slope are interpreted to reflect glacial-interglacial changes in the core location relative to the coastline (sea-level effect), and hence changes in production as the area of coastal upwelling moved on- and offshore as sea-level changed, as well as undoubtedly changes in upwelling intensity through wind forcing. Further studies are needed to fully understand the interrelationships of all these processes, which are required for building more reliable paleoceanographic-paleoclimatic records.

The Northwest African slope apron: a modern analogue for deep-water systems with complex seafloor topography

The Northwest African slope apron is an interesting modern analogue for deep-water systems with complex seafloor topography. A sediment process map of the Northwest African continental margin illustrates the relative roles of different sedimentary processes acting across the entire margin. Fine-grained pelagic and hemipelagic sedimentation is dominant across a large area of the margin, and is considered to result from background sedimentary processes. Alongslope bottom currents smooth and mould the seafloor sediments, and produce bedforms such as erosional furrows, sediment waves and contourite drifts. Downslope gravity flows (debris avalanches, debris flows and turbidity currents) are infrequent but important events on the margin, and are the dominant processes shaping the morphology of the slope and rise. The overall distribution of sedimentary facies and morphological elements on the Northwest African margin is characteristic of a fine-grained clastic slope apron. However, the presence of numerous volcanic islands and seamounts along the margin leads to a more complex distribution of sedimentary facies than is accounted for by slope apron models. In particular, the distribution and thickness of turbidite sands are controlled by the location of the break-of-slope, which is itself controlled by the pre-existing submarine topography.

Block and debris deposits in the high drakensberg, lesotho, southern africa: implications for high altitude slope processes

Past evaluation of high altitude slope development in Lesotho, southern Africa, is largely based on hypothetical or macro‐scale geomorphic approaches. Consequently, the information pertaining to high altitude southern African Quaternary slope environments has remained rather rudimentary. The present study describes the morphology and discusses the likely palaeogeomorphic processes of blockstreams and debris deposits on the Popple Peak and Njesuthi‐Mafadi south‐facing‐slopes in the Drakensberg. The geomorphic evidence provides much needed information to help improve the understanding of south‐facing slope processes during past colder periods. A model for high altitude Drakensberg south facing slopes is presented and used to challenge and expand on recent models and ideas on southern African valley asymmetry. It is found that solifluction and debris flows/avalanches were operative on south‐facing slopes during past cold periods and thereby contributed to past slope development at some high altitude sites in Lesotho. However, the geomorphological observations do not support the valley asymmetry hypothesis and it is suggested that greater caution be exercised in valley‐form interpretations, particularly where geomorphological ground‐truthing has been absent.

Hydrology and currents observed in the channel of Sardinia during the PRIMO-1 experiment from November 1993 to October 1994

The channel of Sardinia is one of the less-known areas of the Western Mediterranean sea. The paths of the Levantine Intermediate Water (LIW), the Tyrrhenian Dense Water (TDW) and the Western Mediterranean Deep Water (WMDW) mainly, in this wide passage, are still debated. Two major aims of the PRIMO-1 (Programme de Recherche International en Mediterranée Occidentale) experiment were to specify the mean circulation paths of these intermediate and deep waters there and to verify hypotheses about the migration of mesoscale eddies from Algeria to Sardinia and their effect on the circulation paths of all the water masses. Despite an important loss of moored instruments, current time series have been collected from November 1993 to October 1994 at four different locations and two CTD cross-sections have been performed. Current meters on the Sardinian slope indicate, during 1 year, an almost permanent alongslope flow toward the northwest in the intermediate and deep layers. Currents recorded on the African slope are always directed alongslope eastward down to 2500 m. Coherently, in the mid-western part of the channel, the bottom flow is northward along the isobaths, while the 200-m flow is southward due to the influence of anticyclonic eddies. At the bottom in the central part of the channel, the current is low and changing: episodes of northeast current along the orientation of the deepest channel axis alternate with westward flows. No seasonal variations have been clearly detected, but the mesoscale variability is large and has a deep signature in the western part of the channel.

A Note on the Diet Synaphobranchus Kaupi (Pisces: Synaphobranchidae) from the Porcupine Seabight, North-East Atlantic

The diet of Synaphobranchus kaupi from the Porcupine Seabight is described. A sample of 110 eel stomachs containing food, were analysed and the general size–depth trend among eels with food in their stomachs. Larger individuals are found in deeper waters. Fish are the main prey for larger eels and crustaceans are preferred by smaller individuals.Synaphobranchus kaupi Johnson, 1862 is a slope dwelling eel, abundant in the north-east Atlantic Ocean from 230 to 2420 m deep on the continental slope (Haedrich & Merrett, 1988). It is the most abundant species on the slopes of the Porcupine Seabight, off south-west Ireland (Merrett et al, 1991; Priede et al., 1994) and was classified as a benthopelagic predator of the fourth level, predator of predators (Saldanha, 1991).The diet of S. kaupi has been described from the slope off the middle Atlantic coast of the USA (Sedberry & Musick, 1978), from the Portuguese slope and in the Bay of Biscay (Saldanha, 1991), from the west African slope (Merrett & Marshall, 1981; Merrett & Domanski, 1985) and from the Rockall Trough (Gordon & Mauchline, 1996).Our specimens were captured during a joint IOS/SAMS survey (Merret et al., 1991). From a total catch of 8792 S. kaupi, captured between 1979 and 1983 in the Porcupine Seabight, ranging from 470 to 2230 m deep, fish stomachs were removed aboard ship and 110 with food were kept in 5% formalin for further analysis.

The Distribution and Diet of the Dominant, Slope-Dwelling Eel, Synaphobranchus Kaupi, of the Rockall Trough

INTRODUCTIONThe deep-sea eel, Synaphobranchus kaupi, is widely distributed on the continental slopes of the North Atlantic (Saldanha & Bauchot, 1986; Haedrich & Merrett, 1988). It was a dominant fish species in epibenthic sledge and semi-balloon otter trawl (OTSB) hauls on the West African slope (Merrett & Marshall, 1981; Merrett & Domanski, 1985). Also in the eastern North Atlantic, it was the most abundant species on the slopes of the Porcupine Sea Bight off south-west Ireland (Merrett et al., 1991; Priede et al., 1994). In the western North Atlantic, it was the dominant species on the middle and lower slopes of the Middle Atlantic States of the USA and on the upper slopes of the Grand Banks off Newfoundland (Sedberry & Musick, 1978; Houston & Haedrich, 1986).

NOTES ON THE GENUSHYMENOCEPHALUSGIGLIOLI, 1884 (TELEOSTEI: MACROURIDAE) IN SOUTHERN AFRICA

SUMMARY The grenadier genus Hymenocephalus is represented in southern African upper slope waters by two species: H. italicus Giglioli, 1884, ranging from the North Atlantic to the eastern Indian Ocean, and If. gracilis Gilbert & Hubbs, 1920, a nearly cosmopolitan species. Hymenocephalus italicus was previously identified in southern African waters as H. heterolepis (Alcock, 1889), which is here re-affirmed as a junior synonym. Hymenocephalus gracilis is newly recorded for the southern African marine ichthyofauna.

Cretaceous and Tertiary sediments from the Northwest African Slope (dredges and cores supplementing DSDP results)

Cretaceous and Tertiary sediments dredged and cored on the continental slpe off Cape Bojador (16 stations between 400 and 2800 water depth) provide stratigraphic and regional data not obtained at nearby DSDP Sites 369 and 397, and give additional information on the poorly documented pre-Quaternary litho- and biofacies of the northwest African continental slope. The structural interpretation of the continental margin is based on geophysical, oil exploration and DSDP information. “Middel” Cretaceous (Albian-Turonian) dark (saproelic) shales with calcareous concretions and belemnites reflect an oxygen-depleted environment, marl- and limestones a more oxygenated slope facies. Major sediment types of the Late Paleogene (Middle Eocene to Oligocene), probably separated from the Late Cretaceous by an unconformity, are calcareous diatom and radiolarian mudstones, weakly silicified radiolarian nannomicrites, well-sorted turbidites, and quartz-, mollusk- and phosphate-rich foraminiferal biomicrites. The abundance of pyrite, fish debris, phosphates, diatoms, radiolarians, and of a low-diversity fauna of opportunistic Buliminacea suggests deposition in an oxygen-depleted upper-slope environment under upwelling conditions. Canyon erosion started during Paleocene/Eocene times. Downslope redeposition (grain-by-grain and by slumping) is significant. During the Neogene (mostly Miocene) the uppermost slope and outer shelf was a starved carbonate platform with phosphatized hardgrounds. It was covered by quartzose and phosphatic dolomites, phosphorites, and local dolomite- and phosphate-cemented eolian-sand turbidites. Middle Miocene diatom mudstones from the intermediate slope reflect upwelling conditions. Major erosion of the lower-slope canyons took place during the Late Oligocene to Early Miocene. It stimulated debris flows which deposited pebbly mudstones with a mixed variety of lithofacies and ages (Albian to Miocene) indicating the extent of erosion into the lower slope.

Neoharriotta carri: A New Species of Rhinochimaeridae from the Southern Caribbean Sea

The genus Neoharriotta has been known from only a single species (pinnata Schnakenbeck) on the west African Slope. A new species, Neoharriotta carri, from the southwestern Caribbean Sea is described, differing in smaller size of adults and egg capsules, by having proportionately longer snout, pectorals, and eyes; shorter dorsal and anal fins; fin positions; profile of snout; angular (maxillary) mucous canal loop pattern; and denticulations on juveniles. A key to the Atlantic Rhinochimaeridae is presented.