Adult Heaviside’s dolphins typically weigh between 60 and 70 kg, with an average body length of 1.74 m. Maximum girth is roughly 67% of the length of the body. Each individual has between 48 and 70 teeth. They are distinguished from other dolphins by their blunt head, robust body, triangular dorsal fin, and rounded paddle-like flippers. Heaviside's dolphins have a dark gray anterior surface with a dark blue-black patch beginning midway between the dorsal fin and the snout, and extending about halfway down the ventral surface of the body. White markings on their underside form a three-pronged fork, with another white rhomboidal patch on the chest and two smaller diamond-like patches just posterior to the flippers. They also have a dark blue-black stripe, which extends from the blowhole to the cape. Sexual dimorphism has not been reported in this species.
Range mass: 60 to 75 kg.
Average length: 1.74 m.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike
There are no known adverse effects of Cephalorhynchus heavisidii on humans. Although local fisherman may contend that this species decreases local fish abundance, there is no documented evidence to support this.
Cephalorhynchus heavisidii is listed as “data deficient” on the IUCN Red List of Threatened Species. CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) lists Cephalorhynchus heavisidii under Appendix II, meaning that though this species is not necessarily threatened with extinction, its trade must be regulated so that its survival is not jeopardized. Cephalorhynchus heavisidii is vulnerable to harpoons and guns used by humans hunting close to shore, where about 100 are killed annually. Also, entanglement in fishing gear poses a significant threat. In 1983, 67 were caught in nets off Namibia, and 57 off of South Africa. Although overfishing of their primary prey may pose a threat to their survival, little evidence exists to support this claim. As an inshore species, C. heavisidii is susceptible to pollution and boat traffic, and low levels of DDT have been found in some individuals. This species is currently protected from commercial hunting and fishing throughout its geographic range. It is also protected by a 322 km Exclusive Fishery Zone (EFZ) off the coast of South Africa and a 20 km EFZ off the coast of Namibia.
CITES: appendix ii
IUCN Red List of Threatened Species: data deficient
Heaviside’s dolphins communicate visually, as dolphins have exceptional underwater vision. They also use tactile communication, swimming near other individuals and rubbing against one another to build affiliative relationships. Acoustically, they are able to communicate through a series of whistles and clicks ranging between 1.5 and 11.0 KHz. They communicate chemically by releasing pheromones from pores in their anal glands. Heaviside’s dolphins also rely heavily on echolocation to perceive their surroundings.
Communication Channels: visual ; tactile ; acoustic ; chemical
Other Communication Modes: pheromones
Perception Channels: visual ; tactile ; acoustic ; echolocation ; chemical
Cephalorhynchus heavisidii provides no known economic benefits to humans.
Cephalorhynchus heavisidii preys upon a number of different fish and cephalopods. Although this species is not a major prey item of any particular organism, body parts of dolphins have been found in the gut contents of killer whales and sharks. There is no information available regarding parasites of Cephalorhynchus heavisidii, nor has it been recorded to take part in any mutualistic or commensalistic relationships with other organisms.
The primary prey of Cephalorhynchus heavisidii includes hake and kingclip, which comprises nearly 49% of their diet. Octopods is also an important prey item for C. heavisidii, which makes up about 22% of their diet. The remainder of their diet generally consists of kingfish, gobies, and squid. Dolphins have fusiform, or torpedo shaped bodies, which allows them to swim at high speeds to avoid predation and catch prey.
Animal Foods: fish; mollusks
Primary Diet: carnivore (Piscivore )
Cephalorhynchus heavisidii is found in coastal waters off of Africa’s Southwestern coast, from central Angola to the southern-most tip of South Africa. This species usually remain within 8 to 10 km of the shoreline, but has been sighted up to 45 nautical miles from the coast. While some studies suggest that Cephalorhynchus heavisidii does not migrate significant distances, and that there are resident dolphins in some areas, this is not well established. One study tracked a juvenile male that swam 158 km north of where he was tagged. Another juvenile male traveled 137 km north of his tagging site over a 17 month period, suggesting that average daily movements might be small. This species appears to have low population densities of around 5 individuals per 160 km.
Biogeographic Regions: ethiopian (Native )
Cephalorhynchus heavisidii is found exclusively in the Atlantic Ocean. Although it is most often found in waters less than 100 m deep, it has been sighted at depths up to 180 m. It is usually found in waters that are between 9 and 15ºC, but has been found in waters as warm as 19ºC. More than 87% of sightings occur in the Benguela Current.
Range depth: 180 (high) m.
Average depth: 100 m.
Habitat Regions: tropical ; saltwater or marine
Aquatic Biomes: pelagic ; coastal
There is no information available regarding the average lifespan of Cephalorhynchus heavisidii in captivity or in the wild. The average lifespan of most wild delphinids ranges from 17 to 25 years, with a few living into their early 50s. Although similar averages are found for captive dolphins, few captive individuals live past their 20s. In general, delphinids are vulnerable to bacterial, fungal, and viral infections and have been found to suffer from heart and respiratory disease, stomach ulcers, and even cancer. Dolphins are also vulnerable to a number of different parasites including flukes, tapeworms, and roundworm.
Though Cephalorhynchus heavisidii is not typically vulnerable to predation, humans pose a potential threat due to by-catch. In general, dolphins are subject to retaliatory killings by local fisherman and are sometimes slaughtered for their meat, which is considered a delicacy in Japan. However, the biggest threat to dolphins seems to be accidental killing. Drift fishing nets catch everything in their paths, including dolphins, and prevent them from reaching the surface for air. It has been estimated that drift fishing nets have killed more than 30 million dolphins worldwide since the 1960's.
Known Predators:
This species is sometimes referred to as Haviside's dolphin, rather than the more common Heaviside's dolphin.
There is no information available regarding the mating system of Heaviside's dolphins. However, bottlenose dolphins, spinner dolphins, and common dolphins are promiscuous.
Heaviside's dolphins breed once every 2 to 4 years from spring to late summer. Gestation lasts for 10 to 11 months. Females usually give birth to only one offspring at a time, as there is limited space for in utero development. To account for the limited space in the uterus, during development, the tail flukes and dorsal fins of fetuses are cartilaginous and fold over. Newborns average 85 cm in length. Birth mass has not been recorded for this species. However, newborn bottlenose dolphins range from 11.3 to 18.1 kg, and Irrawaddy dolphins, which average 96 cm in length at birth, has an average birth mass of 12.3 kg. There is no information available regarding weaning and time to independence for this species. Bottlenose dolphins begin weaning as early as 32 months and are fully weaned by 48 months, while time to independence ranges between 3 and 6 years. Female Heaviside's dolphins reach sexual maturity between 5 and 9 years of age, and males reach sexual maturity between 6 and 9 years of age.
Breeding interval: Haviside's dolphins breed every 2 to 4 years.
Breeding season: Haviside's dolphins breed from spring to late summer.
Range gestation period: 10 to 11 months.
Range age at sexual or reproductive maturity (female): 5 to 9 years.
Range age at sexual or reproductive maturity (male): 6 to 9 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Cephalorhynchus heavisidii calves swim in echelon position, that is, in close proximity to the mid-lateral flank near the dorsal fin of the mother. This allows the calf extra speed at a lower tailbeat frequency, because it is able to ride along the pressure wave that its mother’s body creates. However, it has been shown that this causes extra strain on the mother, who is able to swim at only 76% of her mean maximum speed when swimming by her self. Most dolphin calves develop strong social bonds with their mother, which remains even at 3 years of age. This extended mother-young association is thought to be due largely to the still-improving physical performance and social skills of calves. There is no information available regarding paternal investment in calf development.
Parental Investment: precocial ; female parental care ; pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female); extended period of juvenile learning
Heaviside dolphins (Cephalorhynchus heavisidii)were originally named ‘haviside’ dolphins after Captain Haviside who brought a specimen of the cetacean from the coast of Namibia to the UK in the early 19thcentury.An accidental typo resulted in the cetacean being called a ‘heaviside dolphin’ and the name stuck!
Heaviside dolphins are small and robust.They are roughly the size of an average human.An adult Heaviside dolphin is approximately1.7meters in length and weighs an average of 60 – 70 kgs.They do not have beaks so they are often mistaken for porpoises.
Heaviside dolphins are often seen in small groups of2 – 10 animals.They are shyer than their cetacean cousins but they do occasional bow ride nearby boats.They diet comprises of a variety of prey items found along their coastal habitat that stretches from along the coast of southern Angola to the southern tip of South Africa.Hake and kingklip make upto 50%of its diet. Octopods make up 25% and the remainder comprises of a mix of smaller fish.
There is no data available on the reproductive behaviour of Heaviside dolphins.There is also no data available on longevity.No wonder theIUCN Red listclassifies Heaviside dolphins as a data deficient species.However, threats have been identified for this species.These animals are prone to entanglement in a variety of inshore fishing gear (e.g., beach seines, purse seines, trawls, and gillnets).
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Die Heaviside-dolfyn (Cephalorhynchus heavisidii) is 'n dolfyn wat endemies is aan die Weskus en kom voor vanaf Tafelbaai tot by suidelike Angola. Die bestaan van die spesie word beïnvloed deur die oorbenutting van die stokvis bevolking. Daar is min bekend omtrent die dolfyn. In Engels staan dit bekend as die Heaviside's dolphin.
Die Heaviside-dolfyn (Cephalorhynchus heavisidii) is 'n dolfyn wat endemies is aan die Weskus en kom voor vanaf Tafelbaai tot by suidelike Angola. Die bestaan van die spesie word beïnvloed deur die oorbenutting van die stokvis bevolking. Daar is min bekend omtrent die dolfyn. In Engels staan dit bekend as die Heaviside's dolphin.
Delfin Heaviside (Cephalorhynchus heavisidii) a zo ur morvil dantek.
El dofí de Heaviside (Cephalorhynchus heavisidii) és un petit dofí juganer que, a causa de la seva grandària i la forma del seu cap, pot ser confós amb una marsopa.
Arriben a la maduresa sexual entre els 7 i 9 anys. El període de gestació és probablement de 10 mesos. Els aparellaments ocorren a la primavera i a l'estiu. Es creu que les femelles poden criar, en terme mitjà, cada tres anys.
Viu des de Ciutat del Cap (Sud-àfrica) fins a Namíbia i, possiblement també, a Angola.[2][3]
Els dofins de Heaviside són animals socials i actius. Es congreguen en grups de 5 a 10 individus, i de vegades en grups majors. Són capaços de nedar ràpidament. Part dels seus jocs i activitat social consisteix a saltar verticalment fora de l'aigua, girar en l'aire, i caure de nou al mar sense produir gairebé soroll.
La longevitat màxima coneguda d'un dofí de Heaviside és de 20 anys. Aquest relativament curt temps de vida, al costat del llarg període de cria, causa un baix creixement de l'espècie. Addicionalment, aquest dofí és particularment sensible a la caça.
El dofí de Heaviside (Cephalorhynchus heavisidii) és un petit dofí juganer que, a causa de la seva grandària i la forma del seu cap, pot ser confós amb una marsopa.
Sydafrikansk delfin (Cephalorhynchus heavisidii), også kaldet Heavisides delfin, er en lille delfin, der forekommer ud for det sydvestlige Afrika ved Sydafrika og Namibia. Den ligner de øvrige arter i slægten Cephalorhynchus i kropsform og har en karakteristisk farvetegning i sort, hvid og grå. Den fremtrædende rygfinne er trekantet.[1] Sydafrikansk delfin lever især af fisk i kulmulefamilien.[2]
Sydafrikansk delfin (Cephalorhynchus heavisidii), også kaldet Heavisides delfin, er en lille delfin, der forekommer ud for det sydvestlige Afrika ved Sydafrika og Namibia. Den ligner de øvrige arter i slægten Cephalorhynchus i kropsform og har en karakteristisk farvetegning i sort, hvid og grå. Den fremtrædende rygfinne er trekantet. Sydafrikansk delfin lever især af fisk i kulmulefamilien.
Der Heaviside-Delfin (Cephalorhynchus heavisidii) ist eine kleine Delfinart, die ausschließlich an der Küste von Namibia und der Westküste von Südafrika anzutreffen ist. Er gehört zu der Gattung der Schwarz-Weißen Delfine (Cephalorhynchus).
Der Heaviside-Delfin ist ein relativ kleiner Delfin, der eine Länge von maximal etwa 1,70 Meter Länge bei einem Gewicht von maximal 75 Kilogramm erreicht. Als Neugeborenes Tier beträgt die Länge wahrscheinlich um 0,8 bis 0,85 Meter.[1] Wie bei anderen Arten der Gattung ist der Körper kompakt und der dunkelgraue Kopf ist abgestumpft. Dies führt gelegentlich zu Verwechslungen mit dem Großen Tümmler. Die Flipper sind schmal und paddelförmig mit abgerundeter Spitze, die Finne groß und dreieckig mit breiter Basis. Der Körper ist weitgehend dunkelgrau, die Flanken sowie der vordere Bereich des Körpers sind hellgrau gefärbt und die hintere Körperhälfte sowie alle Flossen sind wieder dunkelgrau. An den Seiten der Brust und unterhalb der Flipper befinden sich weiße Flecken und die Bauchseite hinter den Flippern bis zum Schwanz ist ebenfalls weiß gefärbt, weitere weiße Bereiche befinden sich auf den Flanken und unterhalb der Rückenfinne.[1]
Die Tiere besitzen in jeder Kieferhälfte jeweils 22 bis 28 gleichartige konische Zähne.[1]
Das Verbreitungsgebiet der Art reicht von der südlichen Küste Angolas unterhalb 17° südlicher Breite bis an die Südspitze Südafrikas,[1] wobei die Tiere auch in den Bereichen um Kapstadt und an der Walvis Bay häufig gesichtet werden.[2] Das Gebiet umfasst maximal etwa 1600 Kilometer Küstengebiete.[1] Eine systematische Untersuchung zur Verbreitung und zu den Bestandszahlen des Heaviside-Delfins existiert nicht. Sie sind sehr häufig an der Skelettküste von Namibia zu beobachten und Sichtungen reichen auch über die Nordgrenze Namibias hinaus.[2]
Die Tiere leben vor allem in den flachen Meeresgebieten mit Tiefen von weniger als 100 Metern und einer Entfernung von maximal 8 bis 10 Kilometer vom Kontinentalschelf. Die Wassertemperaturen dieser Gebiete liegen bei 9 bis 15° Celsius. In Südafrika ist die Art zudem wahrscheinlich mit dem kühlen Wasser des Benguelastroms assoziiert.[1]
Die Delfine sind sehr aktive und gesellige Tiere, die sich im Normalfall in Gruppen von fünf bis zehn Tieren sammeln. Sie sind schnelle Schwimmer und springen gelegentlich senkrecht aus dem Wasser, um nach einem Salto wieder sauber einzutauchen. In der Regel leben die Tiere in Paaren oder in Kleingruppen mit weniger als 10 Individuen, Gruppen von mehr als 30 Individuen wurden jedoch ebenfalls dokumentiert. Auch Vergesellschaftungen mit dem Schwarzdelfin (Lagenorhynchus obscurus) wurden beobachtet.[1] Über Wanderungen und die räumliche Nutzung der Art liegen nur wenige Informationen vor, es wird jedoch angenommen, dass Wanderungen auf vergleichsweise kleine Gebiete beschränkt sind, die Aktivitätsbereiche werden auf etwa 300 bis 1000 km2 geschätzt,[1] Weibchen teilweise auch bis 2000 km2.[3][2] Die Tiere wandern während des Tages zur Küste und am Nachmittag und Abend in die weiter außerhalb liegenden Meeresbereiche, wobei diese Wanderungen wahrscheinlich durch das Auftreten der Seehechte als Nahrung und zur Vermeidung von Begegnungen mit Hochseehaien während des Tages gekoppelt sind.[3][1]
Der Heaviside-Delfin ernährt sich vor allem von Fischen und Tintenfischen, die im oberflächennahen Pelagial leben. Zu den dokumentierten Beutetieren gehören der Kap-Seehecht (Merluccius capensis), der Kingklip (Genypterus capensis), Sufflogobius bibarbatus, Loligo reynaudi sowie verschiedene Oktopus-Arten. Häufig kommen die Delfine in Gebieten mit hoher Seehecht-Dichte vor.[1]
Die Geschlechtsreife erreichen die Tiere mit sieben bis neun Jahren. Die Paarungszeit liegt im Frühjahr und Sommer und die Tragzeit dauert etwa zehn Monate an. Es wird angenommen, dass ein Weibchen nur alle drei Jahre ein Kalb gebären kann. Das bekannte Maximalalter liegt mit 20 Jahren relativ niedrig. Das niedrige Höchstalter sowie die langen Pausen zwischen den einzelnen Geburten führen zu einem recht langsamen Populationswachstum und damit zu einer starken Sensibilität gegenüber einer Bejagung.
Der Heaviside-Delfin wird als eigenständige Art innerhalb der Gattung der Schwarz-Weiß-Delfine (Cephalorhynchos) eingeordnet, die aus vier Arten besteht. Die wissenschaftliche Erstbeschreibung stammt von John Edward Gray aus dem Jahr 1828, der ihn als Delphinus heavysidii vom Kap der Guten Hoffnung aus der Provinz Westkap der Republik Südafrika beschrieb. Bray beschrieb 1846 auch die Gattung Cephalorhynchos.[1]
Innerhalb der Art werden keine Unterarten unterschieden.[1]
Der Heaviside-Delfin ist benannt nach einem Schiffskapitän namens Haviside, der als Erster ein Exemplar dieser Delfine von Namibia nach Großbritannien brachte. Bei der Benennung wurde sein Name allerdings verwechselt mit dem eines anderen Kapitäns und Walforschers namens Heaviside. Auf diese Weise hat sich dieser Name in der Benennung des Wales bewährt, einige Forscher und Fachbücher nutzen allerdings den ursprünglich gewollten Namen und benennen das Tier als Haviside’s Dolphin.
In Namibia wird das Tier auch mit dem Trivialnamen Benguela Dolphin bezeichnet (benannt nach dem Benguelastrom).
Der Heaviside-Delfin wird von der International Union for Conservation of Nature and Natural Resources (IUCN) aufgrund fehlender Daten zur Populationsgröße als „data deficient“ (Least Concern, LC) eingeordnet. Konkrete Daten über die Bestände und Bestandsentwicklungen liegen nicht vor und die Tiere sind die am häufigsten gesichteten Delfine vor der Küste von Namibia und in der Region vor Kapstadt belaufen sich Schätzungen auf 3.500 bis 11.300 Individuen dieser Art.[1] Zugleich haben sie einen begrenzten Lebensraum im Bereich der Küstengebiete Namibias und Südafrikas und sie sind durch die lokale Küstenfischerei bedroht.[2] Aufgrund des begrenzten Gebietes und des Fischereidrucks wird befürchtet, dass die genetische Variabilität innerhalb der Populationen begrenzt ist.[4]
Die Tiere sind nach dem Washingtoner Artenschutzübereinkommen geschützt und auf Anhang II gelistet, die direkte Bejagung der Tiere ist entsprechend verboten.[1] Da sie allerdings in küstennahen Fischereigebieten vorkommen, unterliegen sie einem relativ hohen Fischereidruck durch die Küstenfischerei und auch die Jagd mit Harpunen oder Gewehren kommt vor. Die Küstengebiete der Region sind allerdings vergleichsweise gering besiedelt.[1]
Der Heaviside-Delfin (Cephalorhynchus heavisidii) ist eine kleine Delfinart, die ausschließlich an der Küste von Namibia und der Westküste von Südafrika anzutreffen ist. Er gehört zu der Gattung der Schwarz-Weißen Delfine (Cephalorhynchus).
Heaviside's dolphin (Cephalorhynchus heavisidii)[3] is one of four dolphins in the genus Cephalorhynchus. The small cetacean is endemic to the Benguela ecosystem along the southwest coast of Africa.[4][5]
Early in the 19th century, a specimen was caught off the Cape of Good Hope and brought to the United Kingdom by a Captain Haviside of the British East India Company. Zoologist John Edward Gray, who described the species in his Spicilegia Zoologica,[3] misidentified Haviside as the surgeon John Heaviside, whom was known for his own biological collections at the time.[6] "Heaviside's Dolphin" is the recognised common name, though amongst others, "Haviside's dolphin" and "Benguela dolphin" are also used, the latter especially in Namibia.
The genus name "Cephalorhynchus" comes from the Greek kephale for ‘head’ and rhynchos for ‘beak’. For the species name "heavisidii" see the above description.
The three other species in the genus Cephalorhynchus are the Chilean dolphin (C. eutropia), the Commerson's dolphin (C. commersonii) and the Hector's dolphin (C. hectori). All are located in cool temperate shelf waters in the Southern Hemisphere.[7]
Genetic studies suggest that the Cephalorhynchus dolphins originated from a single common ancestor in Southern Africa, from which Heaviside's dolphin are the basal species.[8] Radiation around the southern hemisphere following the Antarctic Circumpolar Current (otherwise known as the West Wind Drift), first to New Zealand and then to South America, is thought to have led to the subsequent speciation within the genus.[8]
Heaviside's are small and stocky with adults reaching a maximum length and weight of 1.7m and 75 kg respectively.[9] The dolphin has a distinct black, grey and white body pattern, and is not easily confused with any other species in its range.[4] The head is cone shaped with a blunt beak. The dorsal fin is triangular in shape and centred in the middle of the back. The head and thorax are coloured light grey with darker patches around the eye. The dorsal fin, fluke and dorsal cape are a dark grey to almost black with a band that extends forward from the dorsal fin to the blowhole. The underbelly is white, with bands that extend onto the lower rear of the body. Small white patches are located just behind the pectoral fins and a single white patch extends between these fins on the chest. Sexual dimorphism is minimal, however variation in the shape of the white patch covering the genital slit is distinct between genders. In males, the patch ends in a point, but in females widens out to cover the mammary slits.[4]
Information on reproduction is limited for Heaviside's dolphins, however they are thought to be comparable to Hector's and Commerson's dolphins.[7] Females and males reach sexual maturity approximately between 5–9 years. Mating is thought to occur year-round, however individual females may only produce calves every 2–4 years. Gestation time is unknown. Maximum known lifespan is based on the oldest recorded individual at 26 years old.[6]
Typically occurs in small groups of 2–3, but numbers of 1-10 are frequent and large aggregations of ~100 individuals or more are known to form in high density areas.[6] Nursery groups (exclusively females and calves) are not formed in this species.[10]
Levels of predation are unknown, however killer whales (Orcinus orca) are known predators and there is evidence of shark attack from body scars.[11]
The species is strongly associated with the cool waters of the Benguela Ecosystem. Although the southern limit of the range is defined as Cape Point, the real southern limit beyond which sightings are extremely rare is Hout Bay, some 40 km to the north (a considerable distance for a species which shows very high site fidelity to quite small spatial scales when nearshore). The species occurs more or less continuously for 2,500 km to the north of this along the South African coast, through Namibia and into southern Angola where the northern boundary for the species remains poorly defined. Several dolphins have been sighted or accidentally caught by fishing vessels north of the Angola-Namibia border,[12][13][14][15] but no sightings were reported during a series of coastal scientific surveys at Tombua which is approximately 170 km into Angola but well south of the defined northern boundary of the Benguela Ecosystem. The northern boundary of the Benguela current shifts north and south seasonally and as Heaviside's dolphins appear closely linked to its cool waters, their northern range limit may shift along with water conditions.[4][5] Systematic surveys have dedicated effort to describing the distribution in southern South Africa[10] and current research efforts focus on local populations in Walvis Bay and Lüderitz, Namibia.[16] These locations are also popular hotspots for watching these dolphins in addition to Table Bay (Cape Town) and Britannia Bay, South Africa. Sightings are common from land and there are several dolphin watching tour companies by which Heaviside's dolphins can be seen by boat.
Recent genetic research has demonstrated evidence of population structure across the range, indicating two metapopulations (north and south) with limited genetic exchange.[17] This pattern of fragmentation is a common feature amongst the other three species in the genus Cephalorhynchus and most prevalent in the Hector's dolphin, which displays genetic isolation over very short distances.[18]
Heaviside's dolphins typically remain nearshore in the mornings where they typically socialise and rest. When nearshore their distribution patterns are remarkably predictable within and between years, with the animals showing highly consistent use of aggregation sites at the exposed western tips of most bays throughout South Africa and Namibia, but they are rarely seen in the protected shallows of these bays. Outside of bays, they show relatively high densities along exposed sandy beaches, but these may be a secondary choice after a preference for areas where there is a high abundance of their main prey item; juvenile hake (Merluccius capensis) in adjacent offshore waters. Most commonly sighted within sea surface temperatures of 9 to 15 °C (48 to 59 °F) and depths less than 100 metres (330 ft).[14]
Heaviside's dolphins are energetic and social animals, especially when nearshore in the mornings Behaviour when offshore tends to be less playful an may include a rest phase when moving offshore to feed. They are attracted to boats and frequently bow-ride.[19] Individuals can also be seen surfing in coastal waves. Iconic vertical leaps clear the water before re-entering headfirst with almost no splash.[6] Heaviside's dolphins use echolocation to find and capture prey.[20] Mating typically occurs in social groups of 3-7 individuals which remain in a small area exhibiting extensive rolling, touching and position changes with frequent leaps by one of pairs of animals which potentially serve a competitive function.
Prey items consist of mostly demersal fish and cephalopod species, predominantly juvenile hake (Merluccius capensis) and octopus, however pelagic species such as juvenile goby (Sufflogobius bibarbatus) and horse mackerel (Trachurus trachurus capensis) are also consumed especially in Namibia.[21] Foraging occurs mostly at the seabed, in shallow depths. Feeding nearshore is rarely observed.
A diurnal movement pattern is present in South Africa, whereby the dolphins move offshore in the afternoon to feed on prey rising vertically to the surface at night.[22] Movement inshore to rest and socialise occurs in the morning.[19] However, the pattern is different in Luderitz and Walvis Bay, Namibia where the movement is less pronounced and dolphins appear to stay inshore during the night, which is likely associated with foraging on different prey.[23]
Heaviside's have small home ranges of 50–80 km as measured using satellite telemetry over 2–3 months and photographic resightings over up to 3 years.[24] Some individuals have been resighted at the same location for up to 10 years.[24][25]
There has been limited research into Heaviside's diving behaviour, however a study of two dolphins fitted with satellite tags was undertaken in South Africa in 1997.[26] The maximum dive depth recorded was 147 meters, however the majority of dives were less than 50 meters.[26] Dive duration were predominantly less than 2 minutes with most dives between 0 and 1 minutes (Davis et al. 2014).[26]
Whilst typically found further from shore, dusky dolphins (Lagenorhynchus obscurus) are found throughout the range and occasionally both dolphin species are sighted in mixed groups.[10] Where both species overlap in prey selection, Heaviside's take larger prey items, potentially because they are outcompeted by the larger dusky dolphins for their preferred, smaller sized prey.[27] In central Namibia (especially Walvis Bay) Heaviside's dolphins overlap with a small populations of fewer than 100 common bottlenose dolphins REF. The bottlenose dolphin population use only water less than 15m depth while in this area Heaviside's dolphins are almost always encounteres in water deeper than 20m, suggesting some form of competitive exclusion.
As is the case with all species in the genus, Heaviside's dolphins produce narrow-band high-frequency (NBHF) echolocation clicks (centred around 125–130 kHz), and do not whistle.[28] This adaptation is theorised to allow acoustic crypsis from eavesdropping predators, as the sounds produced are outside of the detectable frequencies of killer whales.[29] Although NBHF clicks are limited in acoustic range, they have a better resolution for small targets and are thought to provide a foraging advantage in the often cluttered, nearshore environment in which these species occur.[30] Heaviside's also produce a second click type, of lower frequency and broader bandwidth, that is within the hearing range of killer whales.[31] These calls are produced most frequently in groups engaging in social behaviour. It is likely that the dolphins use these calls when socialising away from predator threat and switch to high frequency clicks when foraging and travelling.[32]
No total abundance estimate currently exists, however a population estimate of 6,345 for the region between Table Bay and Lamberts Bay, South Africa represents the southernmost populations in the species range.[19] Local population estimates for Walvis bay and Lüderitz are 508 and 494 respectively.[5] A visual and acoustic line-transect ship survey estimated an average of 1594 dolphins in the Namibian Islands’ Marine Protected Area (NIMPA) which spans 400 km of coastline along southern Namibia (REF Martin et al. 2020). Quantification of abundance throughout the range is still required.
Heaviside's dolphins are exposed to a variety of threats given their limited range in coastal shallow waters which are subject to a range of anthropogenic activities. Directed catch has occurred historically, with meat being used for human consumption.[33]
Heaviside's dolphins are exposed to several poorly quantified and rapidly changing human threats including fisheries bycatch related mortality and illegal directed catch (Elwen and Gopal, 2018; Alfaro-Shigueto et al., 2019). Recently developed mid water trawls for horse mackerel (Trachurus capensis) are considered an emerging threat.[5]
Heaviside's dolphins are listed amongst the cetacean species most vulnerable to climate change [34] as they are limited to a distribution range that includes both suitable shelf habitat and cool water temperatures (Best, 2007). The Benguela Current is the only eastern-boundary current bordered by warm-water currents at both its northern and southern limits. Consequently, small increases in water temperature could result in all shelf waters in this area becoming too warm for both species, and populations are expected to decline rather than shift poleward due to a lack of shelf habitat.
Heaviside's dolphins may be exposed to increase in the marine eco-tourism business in Namibia, which has grown without regulation in Walvis Bay (Leeney, 2014). Negative effects have been demonstrated for other coastal cetacean species, for example the impact of tour boats on bottlenose dolphin behaviour in Walvis Bay includes a reduction in resting behaviour and an increase in socialising behaviour in the presence of tour boats (indurkyhua). One Heaviside's dolphin was documented in 2010 with evidence of a propeller strike along its flank. As individuals have small home ranges they may be vulnerable to localised threats.
Prior to 2018, the International Union for Conservation of Nature (IUCN) listed the Heaviside's as ‘Data Deficient’ however, as of 2017 the status was changed to ‘Near Threatened’,[1] owing to improved knowledge on the species from multiple studies. Despite this, the overall population trend remains unknown,[5] and there are many aspects of the species biology that remain to be studied
Heaviside's dolphin is listed on Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals[35] and is included in the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia. The Memorandum of Understanding was established in 2008 and aims to protect these species at a national, regional and global level.
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{{cite web}}: CS1 maint: url-status (link) Heaviside's dolphin (Cephalorhynchus heavisidii) is one of four dolphins in the genus Cephalorhynchus. The small cetacean is endemic to the Benguela ecosystem along the southwest coast of Africa.
El delfín de Heaviside o delfín de Haviside (Cephalorhynchus heavisidii) es una especie de cetáceo odontoceto de la familia Delphinidae. Es un delfín pequeño que habita costas de Namibia y la costa oeste de Sudáfrica. Es uno de las cuatro especies del género Cephalorhynchus.
El nombre común "delfín de Heaviside" se comenzó a utilizar cuando el capitán Haviside, prominente cirujano real, coleccionista de cetáceos y otras especies animales, llevó un espécimen desde las costas de Namibia al Reino Unido a principios del siglo XIX. El nombre fue posteriormente mal pronunciado y transcrito y es el más común en la literatura. Sin embargo algunas autoridades científicas, incluyendo la Enciclopedia de mamíferos marinos[2] y Especies de mamíferos del mundo[3] usan el nombre original, "delfín de Haviside".
El delfín de Heaviside es un pequeño delfín juguetón, que alcanza aproximadamente los 180 centímetros de longitud y llega a pesar hasta 75 kilogramos. Su tamaño y la forma de su cabeza suelen producir confusión con las marsopas. La cabeza es gris oscuro, la mitad frontal de su dorso y la parte superior de los flancos es gris claro. Las aletas y la mitad trasera del lomo son nuevamente gris oscuro. El vientre es blanco y tiene líneas blancas en los flancos hasta la aleta dorsal.
Alcanzan la madurez sexual entre los 7 y 9 años. El período de gestación es probablemente de 10 meses. Los apareamientos ocurren en primavera y verano. Se cree que las hembras pueden criar en promedio cada tres años. La longevidad máxima conocida de un delfín de Heaviside es de 20 años. Este relativamente corto tiempo de vida, junto al largo período de cría, causa un bajo crecimiento de la especie. Adicionalmente, este delfín es particularmente sensible a la caza.
Los delfines de Heaviside son animales sociales y activos. Se congregan en grupos de 5 a 10 individuos, y a veces en grupos mayores. Son capaces de nadar rápidamente. Parte de sus juegos y actividad social consiste en saltar verticalmente fuera del agua, girar en el aire, y caer de nuevo al mar sin producir casi ruido.
Como el avistamiento de especies no es muy común en la Costa de los Esqueletos de Namibia, el delfín de Heaviside no ha sido estudiado en forma sistemática por los científicos. Han sido observados fuera de las costas del norte de Namibia a 17º S, y hacia el sur hasta el extremo meridional del continente africano (Cabo de Buena Esperanza). Los avistamientos se realizan frecuentemente desde los principales centros poblados, como Ciudad del Cabo y ciudades como Walvis Bay. La estimación es que no es una especie abundante.
En 2008 la especie fue catalogada en la Lista Roja de la UICN, como datos insuficientes, por falta de información sobre el tamaño de la población, su tendencia y amenazas. Estos delfines tienen un rango de distribución adecuado y no son particularmente abundantes en ningún sitio. Algunas amenazas se han identificado, como ser víctimas de ahogamiento al enredarse en los aparejos de pesca ubicados cerca a la costa.[1]
El delfín de Heaviside o delfín de Haviside (Cephalorhynchus heavisidii) es una especie de cetáceo odontoceto de la familia Delphinidae. Es un delfín pequeño que habita costas de Namibia y la costa oeste de Sudáfrica. Es uno de las cuatro especies del género Cephalorhynchus.
Cephalorhynchus heavisidii Cephalorhynchus generoko animalia da. Artiodaktiloen barruko Delphinidae familian sailkatuta dago.
Cephalorhynchus heavisidii Cephalorhynchus generoko animalia da. Artiodaktiloen barruko Delphinidae familian sailkatuta dago.
Benguelandelfiini (Cephalorhynchus heavisidii) eli namibiandelfiini on kirjodelfiinien sukuun kuuluva laji. Benguelandelfiinillä, kuten kaikkilla kirjodelfiineillä, on vankka rakenne ja tylppä kuono. Sen vatsapuolella on valkoisia kuvioita. Benguelandelfiiniä tavataan Afrikan lounaisosan rannikolla.
Se elää yleensä melko kylmissä vesissä, 9–19 °C:ssa. Benguelandelfiinit elävät joko yksin tai pienissä laumoissa. Laji käyttää ravintona kaloja ja mustekaloja. Benguelandelfiini on rauhoitettu. Sitä kuitenkin pyydetään laittomasti ja sen lisäksi lajia uhkaavia tekijöitä ovat verkkokalastus, liikenne ja saasteet.[3]
Benguelandelfiinin kokonaisyksilömäärää ei ole tiedossa, mutta levinneisyysosan eteläosissa se vaikuttaa olevan suhteellisen runsaslukuinen. Kansainvälinen luonnonsuojeluliitto pitää lajia silmälläpidettävänä.[4]
Benguelandelfiini (Cephalorhynchus heavisidii) eli namibiandelfiini on kirjodelfiinien sukuun kuuluva laji. Benguelandelfiinillä, kuten kaikkilla kirjodelfiineillä, on vankka rakenne ja tylppä kuono. Sen vatsapuolella on valkoisia kuvioita. Benguelandelfiiniä tavataan Afrikan lounaisosan rannikolla.
Se elää yleensä melko kylmissä vesissä, 9–19 °C:ssa. Benguelandelfiinit elävät joko yksin tai pienissä laumoissa. Laji käyttää ravintona kaloja ja mustekaloja. Benguelandelfiini on rauhoitettu. Sitä kuitenkin pyydetään laittomasti ja sen lisäksi lajia uhkaavia tekijöitä ovat verkkokalastus, liikenne ja saasteet.
Benguelandelfiinin kokonaisyksilömäärää ei ole tiedossa, mutta levinneisyysosan eteläosissa se vaikuttaa olevan suhteellisen runsaslukuinen. Kansainvälinen luonnonsuojeluliitto pitää lajia silmälläpidettävänä.
Cephalorhynchus heavisidii
Le dauphin du Cap (Cephalorhynchus heavisidii) est une espèce de mammifères de l'ordre des cétacés.
Cephalorhynchus heavisidii
Le dauphin du Cap (Cephalorhynchus heavisidii) est une espèce de mammifères de l'ordre des cétacés.
Il cefalorinco di Heaviside (Cephalorhynchus heavisidii) è un piccolo delfino che vive al largo delle coste della Namibia e delle coste occidentali del Sudafrica. È uno dei quattro delfini del genere Cephalorhychus - gli altri sono il cefalorinco eutropia, il cefalorinco di Hector e il cefalorinco di Commerson.
Il cefalorinco di Heavisidii viene attualmente chiamato così in onore di un tale Capitano Haviside che ne portò un esemplare dalla Namibia al Regno Unito agli inizi del XIX secolo. Comunque il suo nome venne poi storpiato in Heaviside, in onore di un celebre chirurgo, il Capitano Heaviside, che collezionava cetacei e altre specie animali. L'ultimo nome è resistito ed è il più comune nella letteratura popolare. Comunque alcuni autori, tra cui quelli dell'Encyclopedia of Marine Mammals e di Mammal Species of the World, usano il nome originale - cefalorinco di Haviside.
Sebbene gli avvistamenti della specie non siano infrequenti al largo della Costa degli Scheletri della Namibia, i cefalorinchi di Heaviside non sono stati studiati approfonditamente dagli scienziati. Sono stati registrati al largo della costa della Namibia settentrionale a 17° S e nell'estremo meridione della punta meridionale del Sudafrica. Degli avvistamenti vengono spesso registrati nei pressi di importanti centri abitati come Città del Capo e in città come Walvis Bay. Nella baia di Lambert possono essere avvistati dalla costa o a bordo delle imbarcazioni che si dirigono verso il porto. Non esiste alcuna stima del loro numero.
Il cefalorinco di Heaviside è un delfino piccolo e grazioso che cresce fino a circa 180 cm di lunghezza e può pesare fino a 75 kg. Le sue dimensioni e la rotondità della sua testa fanno sì che spesso venga scambiato per una focena. La testa è di color grigio scuro. La metà superiore della fronte e i fianchi sono di un grigio più chiaro. La pinna dorsale, le natatoie e la metà posteriore del dorso sono a sua volta di color grigio più scuro. Il ventre è bianco e ci sono anche tracce di bianco sui fianchi dietro alla pinna dorsale.
I maschi raggiungono la maturità sessuale a circa 7-9 anni. Le femmine raggiungono l'età riproduttiva nello stesso periodo. Il periodo di gestazione è probabilmente di 10 mesi. L'accoppiamento avviene in primavera ed estate. Si crede che le femmine partoriscano una volta ogni tre anni. L'età massima conosciuta di un cefalorinco di Heaviside era di 20 anni. Questa speranza di vita relativamente breve, insieme al lungo periodo tra un parto e l'altro, provocano una bassa crescita naturale della popolazione. Quindi la specie è troppo sensibile per essere oggetto di caccia.
I cefalorinchi di Heaviside sono animali attivi e sociali. Si raggruppano solitamente in gruppi di circa 5-10 individui e a volte anche in gruppi più numerosi. Sono in grado di nuotare velocemente. Una parte delle attività ludiche e sociali consiste nel saltare verticalmente fuor d'acqua, roteare in aria e ricadere in mare senza fare alcuno schizzo o il minimo rumore.
Il cefalorinco di Heaviside (Cephalorhynchus heavisidii) è un piccolo delfino che vive al largo delle coste della Namibia e delle coste occidentali del Sudafrica. È uno dei quattro delfini del genere Cephalorhychus - gli altri sono il cefalorinco eutropia, il cefalorinco di Hector e il cefalorinco di Commerson.
De Havisidedolfijn (Cephalorhynchus heavisidii) of - verkeerd gespeld - Heavisidedolfijn is een Afrikaanse soort dolfijn uit het geslacht Cephalorhynchus.
De dolfijnensoort is genoemd naar Haviside, een kapitein van de British East India Company, die het eerste specimen naar Engeland bracht. De soort wordt echter vaak toegeschreven aan de arts Heaviside, die specimens niet afkomstig van walvissen aan het British Museum verkocht. De foute naam wordt echter gebruikt in de soortaanduiding heavisidii, die volgens de regels niet kan worden veranderd. Ook in de populaire namen komt de foute naam algemeen voor.[1][2][3]
De Havisidedolfijn komt voor in het zuidwesten van Afrika, van Kaap de Goede Hoop (Zuid-Afrika) via Angola tot Kaap Kruis (Noordwest-Namibië). Hij leeft vooral in kustgebieden met water dat hoogstens 100 meter diep is, maar is ook op ruim 70 kilometer van de kust waargenomen. Ze komen meestal voor in groepjes van hooguit 10 exemplaren, maar dat kan oplopen tot 20 tot 30 exemplaren. Het vaakst komen ze voor in paren en trio's.[2] Vermoedelijk wisselt de samenstelling van de groepjes. Het is een eerder schuwe en weinig actieve soort die zich soms toch voor langere tijd bij kleine schepen waagt. Hij maakt soms snelle voorwaartse salto's tot twee meter hoog die eindigen met een slag van de staart op het water.
Het is onbekend hoe groot de populatie is. Ze lijken nergens in hun leefgebied erg algemeen voorkomend te zijn.[1]
De dolfijnensoort wordt tussen 1,2 en 1,75 meter lang en weegt tussen 40 en 75 kilogram. Een kalf wordt geboren met een lengte van 0,8 tot 0,85 meter en weegt 9 à 10 kilogram. Het kalf lijkt op de volwassen exemplaren, maar is slanker, meer effen donker.
De Havisidedolfijn is grijs met een witte buik met de vorm van een drietand. De twee buitenste, vingervormige "tanden" lopen van de buik naar de flanken; bij vrouwtjes is die soms wat groter dan bij mannetjes. De buikvlek is rond de anus verschillend tussen de seksen. Van de keel tot de borstvinnen heeft de dolfijn een witte oksel. Vanaf het blaasgat loopt er een zwartblauwe lijn die breder wordt iets voor de rugvin en zo afloopt via de achterflanken tot de staart. Op de bovenkant van de staartaanzet zit een variabele, lichte streep. De kop is kegelvormig en heeft geen opvallende snuit. Rond het oog en op de snuit bevindt zich een donkere ovale vlek die overgaat in de lichtere kleur van de rest van het voorlijf. De nek heeft een bruingrijze tot paarsgrijze tint. Er zijn Havisidedolfijnen waargenomen die nagenoeg wit zijn.
De staart heeft een inkeping in het midden en loopt uit in twee gebogen, ronde punten. De flippers zijn relatief kort en hebben een stompe punt. De rugvin is zwart, driehoekig en puntig; dit in tegenstelling tot de andere soorten van het geslacht, die een rondere rugvin hebben[2]. De rugvin is licht variabel. De staartaanzet is bij vrouwtjes soms wat groter dan bij mannetjes.
Elke tandenrij van een exemplaar telt zo'n 22 à 28 kleine, scherpe tanden.[2]
Op het menu van de Havisidedolfijn staat vooral bodemvis, zoals jonge heek. Daarnaast eten ze ook andere vissen, koppotigen en schaaldieren.
Er is weinig bekend over de voorplanting van deze soort, maar kalfjes worden waargenomen van oktober tot en met januari.
De Havisidedolfijn staat minder bloot aan bedreigingen dan de andere soorten uit zijn geslacht. De voornaamste bedreigingen bestaan uit vervuiling, bootverkeer en verstikking in visnetten.[1] Soms worden ook exemplaren gevangen voor menselijke consumptie.[2]
De Havisidedolfijn (Cephalorhynchus heavisidii) of - verkeerd gespeld - Heavisidedolfijn is een Afrikaanse soort dolfijn uit het geslacht Cephalorhynchus.
Multimedia w Wikimedia Commons Tonin afrykański[4], tonin[5][a] (Cephalorhynchus heavisidii) – gatunek walenia z rodziny delfinowatych występujący w morzach południowo-zachodniej Afryki[2][3]. Długość ciała wynosi 174 cm, masa ciała 60-75 kg[6]. Głowa i ogon mają kolor ciemnoszary, a boki są jaśniejsze. Delfin ten żyje maksymalnie do 20 lat. Występuje w grupach liczących od 5 do 10 okazów. Potrafi dosyć szybko pływać i wyskakiwać nad wodę. Opisany w 1828 roku przez Johna Edwarda Graya.
Tonin afrykański, tonin (Cephalorhynchus heavisidii) – gatunek walenia z rodziny delfinowatych występujący w morzach południowo-zachodniej Afryki. Długość ciała wynosi 174 cm, masa ciała 60-75 kg. Głowa i ogon mają kolor ciemnoszary, a boki są jaśniejsze. Delfin ten żyje maksymalnie do 20 lat. Występuje w grupach liczących od 5 do 10 okazów. Potrafi dosyć szybko pływać i wyskakiwać nad wodę. Opisany w 1828 roku przez Johna Edwarda Graya.
O golfinho-de-heaviside (Cephalorhynchus heavisidii) é um cetáceo da família dos delfinídeos encontrado águas costeiras do sul da África, da África do Sul (Cidade do Cabo) à Namíbia e talvez no sul de Angola.
O golfinho-de-heaviside (Cephalorhynchus heavisidii) é um cetáceo da família dos delfinídeos encontrado águas costeiras do sul da África, da África do Sul (Cidade do Cabo) à Namíbia e talvez no sul de Angola.
Bengueladelfin (Cephalorhynchus heavisidii) är en art i släktet Cephalorhynchus som tillhör familjen delfiner. Den förekommer bara vid kustlinjen av Namibia och västra Sydafrika.
Arten är jämförelsevis liten med en maximal kroppslängd på 1,75 meter och en vikt omkring 75 kilogram.[2] Huvudet påminner om öresvinet och därför förväxlas dessa arter ibland. Vid främre kroppen är sidorna ljusgrå och längre bakåt mörkgrå. Buken och några fläckar under ryggfenan (som ibland sammanhänger) är vitaktiga.
Parningstiden ligger i våren eller sommaren. Enligt antagningar har honor förmåga att para sig vart tredje år. Dräktigheten varar i tio månader. Ungdjur blir efter sju till nio år könsmogna och livslängden uppgår till 20 år. Därför ökar populationen bara långsamt och beståndet är mycket känslig för jakt.
Bengueladelfinen lever mycket socialt i grupper av två till tio individer.[2] De simmar särskild fort och hoppar ibland lodrätt ur vattnet. Efter en saltomortal dyker de åter ner i havet.
Födan utgörs bland annat av fiskar som lever i mindre stim, fiskar som vilar på havets botten samt av bläckfiskar.[2]
En systematisk undersökning över population och utbredning saknas. Arten iakttogs från Namibias norra gräns en bit norrut och söderut till Kapstaden. Många individer observerades vid Walvis Bay.
Det vetenskapliga epitet, heavisidii, syftar på en sjökapten med namnet Haviside som fångade det första exemplaret och tog med det till Storbritannien. Där förväxlades han med en annan sjöfarare och valforskare med namnet Heaviside. I några engelskspråkiga böcker kallas arten med det ursprungligen tänkta namnet, Haviside's Dolphin.
Wikimedia Commons har media som rör Bengueladelfin.
Bengueladelfin (Cephalorhynchus heavisidii) är en art i släktet Cephalorhynchus som tillhör familjen delfiner. Den förekommer bara vid kustlinjen av Namibia och västra Sydafrika.
Benguela yunusu ya da Heaviside yunusu (Cephalorhynchus heavisidii) Cephalorhynchus cinsindeki dört yunus türünden biridir. Namibya kıyısında ve Güney Afrika'nın batı kıyısında bulunur. Haviside yunusu ve Güney Afrika yunusu diye de bilinir.
Heaviside yunusunun adı 19. yüzyılın başlarında Namibya'dan Birleşik Krallık'a bu türden bir yunusu getiren gemi kaptanı Haviside 'ın adından gelmektedir. Ancak ismi deniz memelileri ve diğer hayvan türleri toplayan önde gelen cerrah yüzbaşı Heaviside ile karıştırılmıştır. Bu karışıklık nedeniyle popüler literatürde ikinci isim daha çok kullanılmaktadır.
Benguela yunusu 1,80 metrelik boyu ve 75 kg.'luk ağırlığıyla küçük bir yunustur. Boyutları ve küt burunları nedeniyle bu yunuslar porpoise ile karıştırılırlar. Başları koyu gridir. Sırtlarının ön kısmı ile yanları daha açık gridir. Sırt yüzgeçleri, kuyrukları ve sırtlarının arka kısmı yine koyu gridir. Karınları beyazdır ve sırt yüzgeci altında yanlarda beyazlıklar bulunur.
Erkekler cinsel erişkinliğe 7-9 yıl arasında ulaşır. Dişiler de aynı zamanda doğurganlığa ulaşır. Hamilelik dönemi büyük bir olasılıkla on aydır. Çiftleşme ilkbaharda ve yazları olur. Dişilerin her üç yılda bir doğurduğuna inanılmaktadır. Benguela yunusunun bilinen maksimum yaşı yirmi yıldır. Görece kısa olan bu yaşam süresi ve aralıklı doğumlar doğal olarak popülasyonun düşük bir artış hızına sahip olmasına neden olur. Bu nedenle bu türün popülasyon sayısı avlanmaya karşı oldukça hassastır.
Benguela yunusları hareketli ve sosyal hayvanlardır. Tipik olarak 5-10 bireyden oluşan ve bazen de daha büyük gruplarla dolaşırlar. Çok hızlı yüzebilirler. Oyunlarının ve sosyal aktivitelerinin bir parçası da dik olarak denizden dışarı sıçramak, havada dönmek ve ses çıkarmadan ve su sıçratmadan tekrar denize dalmaktır.
Her ne kadar Namibya'nın İskelet Sahili açıklarında gözlemlenebilseler de Benguela yunusu biliminsanları tarafından sistematik olarak incelenmemiştir. Namibya'nın kuzey sahilinde 17° güney enleminden Güney Afrika'nın güney ucuna kadar bir aralıkta görülmektedirler. Cape Town gibi nüfusu yoğun şehirlerle, Walvis Bay gibi kasabalardan gözlemlendikleri bildirilmektedir. Lambert's Körfezi'nde jıyıdan ya da limandan yapılan tekne gezilerinde görülebilirler. Sayıları hakkında bir tahminde bulunulmamıştır.
Benguela yunusu ya da Heaviside yunusu (Cephalorhynchus heavisidii) Cephalorhynchus cinsindeki dört yunus türünden biridir. Namibya kıyısında ve Güney Afrika'nın batı kıyısında bulunur. Haviside yunusu ve Güney Afrika yunusu diye de bilinir.
Cephalorhynchus heavisidii — вид ссавців родини дельфінових. Це найменший дельфін, довжиною 1,2 метра і вагою 40 кілограмів.
Країни поширення: Ангола, Намібія, ПАР.
Cephalorhynchus heavisidii — вид ссавців родини дельфінових. Це найменший дельфін, довжиною 1,2 метра і вагою 40 кілограмів.
Cá heo Heaviside (danh pháp hai phần: Cephalorhynchus heavisidii) là một loài động vật có vú trong họ Cá heo đại dương, bộ Cá voi. Loài này được nhà động vật học John Edward Gray mô tả vào năm 1828.[2]
Cá heo Heaviside (danh pháp hai phần: Cephalorhynchus heavisidii) là một loài động vật có vú trong họ Cá heo đại dương, bộ Cá voi. Loài này được nhà động vật học John Edward Gray mô tả vào năm 1828.
Дельфин Хэвисайда[1] (лат Cephalorhynchus heavisidii) — вид дельфиновых, представитель рода Пёстрые дельфины (Cephalorynchus).
Как и все виды данного рода, имеет маленькое коренастое тело и короткую, широкую голову. Взрослые особи достигают 1,74 м в длину и весят 60—70 кг. Грудные плавники округлены, спинной плавник относительно крупный, треугольный. Окрас серый с черно-синим пятном, тянущимся от области между спинным плавником и рыла до половины брюшной части тела, так же есть черно-синяя полоса, тянущаяся от дыхала до спинного плавника, и пятна такого же цвета на грудных плавниках и вокруг глаз. На животе есть белое пятно в виде трезубца, как у косаток, так же есть белое ромбовидное пятно на груди и два маленьких пятнышка за грудными плавниками. Во рту от 48 до 70 зубов.
Обитает в прибрежных водах Южной Африки, от Северной Намибии до Кейптауна. Предпочитает мелкие прибрежные воды глубиной до 100 м, на расстоянии 8—10 км от берега, температурой 9—15 °C.
Обычно держатся группами по 2—3 особи, иногда по 4—10 особей или по одиночке. Утро проводят в прибрежных водах, а остаток дня в открытых. Такой распорядок дня отражает поведение их добычи, особенно рыб семейства морские налимы, которые мигрируют к верхним слоям воды ночью. В первой половине дня в прибрежных водах дельфины отдыхают, общаются и избегают хищников.
Иногда сопровождают суда и катаются на их носовой волне. Могут выпрыгивать на высоту до двух метров над водой.
Питается рыбой из семейств морские налимы, сериола, бычковые, а также осьминогами и кальмарами.
Они имеют исключительное подводное зрение и используют его для коммуникации. Так же используют тактильное общение, плавают рядом друг с другом и гладят друг друга для поддержания прочных взаимоотношений. Иногда общаются с помощью свистов и щелчков в диапазоне от 1,5 до 11,0 кГц. Так же взаимодействуют химически, выделяя феромоны из пор их анальных желез.
Дельфины Хэвисайда очень сильно полагаются на эхолокацию для восприятия окружающей среды.
Иногда подвергаются охоте браконьеров и запутываются в сетях.
Так же, учитывая относительно маленькую площадь распространения этих дельфинов, загрязнение их среды обитания и чрезмерный вылов рыбы могут отрицательно влиять на их численность.
Однако, на данный момент, данных для оценки угрозы недостаточно, но вид не считается редким.
Дельфин Хэвисайда (лат Cephalorhynchus heavisidii) — вид дельфиновых, представитель рода Пёстрые дельфины (Cephalorynchus).
赫氏海豚（學名：Cephalorhynchus heavisidii），又名海氏矮海豚，是黑白海豚属下的一種海豚，生活在納米比亞到南非西海岸沿海地區。
19世紀早期，有人在好望角附近捉到了一只海豚，這只海豚由英屬東印度公司的赫维赛德船長（Captain Haviside）帶到英國，動物學家约翰·爱德华·格雷在《Spicilegia Zoologica》一書中對其進行了描述。但是他把這名船長的名字“Haviside”和另外一個收集動物標本的外科醫生“Heaviside”弄混了，結果現在英語文學中赫氏海豚通常都叫做“Heaviside's Dolphin”。不過實際也有別的一些機構使用正確的原名。[2][3][4]
分類 界 : 動物界 Animalia 門 : 脊索動物門 Chordata 亜門 : 脊椎動物亜門 Vertebrata 綱 : 哺乳綱 Mammalia 目 : 鯨偶蹄目 Cetartiodactyla 亜目 : ハクジラ亜目 Odontoceti 科 : マイルカ科 Delphinidae 属 : イロワケイルカ属 Cephalorhynchus 種 : コシャチイルカコシャチイルカ（小鯱海豚、Cephalorhynchus heavisidii）はクジラ目ハクジラ亜目マイルカ科イロワケイルカ属に属するイルカである。イロワケイルカ属を構成する四つの種の一つ。ナミビア沖、南アフリカの西側沖に棲息する。
英名である Heaviside's Dolphin（ヘビサイドのイルカ）は19世紀初頭にナミビアからイギリスに標本を持ち込んだキャプテン Haviside（ヘビサイド）の名前に由来する。しかし、クジラ目の生物などの蒐集で著名だった外科医キャプテン Heaviside（ヘビサイド）と混同され、間違ったスペルである Heaviside が定着してしまい、それが学名にも使用されている。しかしながら一部の専門家（例えば、Encyclopedia of Marine Mammals（海棲哺乳類百科事典）の著者）は Haviside's Dolphin と呼んでいる。
コシャチイルカはイルカとしてはかなり小さな種類であり、成体の体長は180センチメートル弱、体重は75キログラム程度である。サイズとずんぐりした頭部形状からネズミイルカと見間違うことが良くある。頭部は濃い灰色である。背の頭側半分および側面は少し明るい灰色である。背びれ、背の尾側半分および尾びれは濃い灰色である。腹側は白く、背びれ付近の側面には白い模様がある。
雌雄とも、7歳から9歳で性成熟する。妊娠期間は約10か月間である。春と夏に交尾する。雌は3年に1度のペースで出産すると考えられている。知られている限りの最長齢は20歳である。この比較的短い寿命と、長い育児期間は、生息数の増加率が低いことを意味する。そのため、コシャチイルカの生息数は捕獲による影響が非常に大きい。
コシャチイルカの組織的・科学的な調査は行われていないが、ナミビアのスケルトン海岸 (Skeleton Coast) の沖で見られることはほとんどない。北限はナミビアの北側である南緯17度、南限は南アフリカの南端である。南アフリカのケープタウン沖やナミビアのウォルビスベイ沖における観察例が多く、これらの地が主な棲息地であると考えられている。総生息数は不明である。
コシャチイルカは活発で社会的な動物である。5頭から10頭程度の群を成すが、時にはより大きな群を成すこともある。非常に速く泳ぐことができる。水面から垂直に跳躍したり、跳躍して空中で回転したり、音をあまり立てずに着水したり、といった行動が観察されている。
この項目は、動物に関連した書きかけの項目です。この項目を加筆・訂正などしてくださる協力者を求めています（Portal:生き物と自然／プロジェクト:生物）。 コシャチイルカ（小鯱海豚、Cephalorhynchus heavisidii）はクジラ目ハクジラ亜目マイルカ科イロワケイルカ属に属するイルカである。イロワケイルカ属を構成する四つの種の一つ。ナミビア沖、南アフリカの西側沖に棲息する。
하비사이드돌고래(Cephalorhynchus heavisidii, 영어: Haviside's dolphin ) 또는 히비사이드돌고래(Heaviside's Dolphin, 헤비사이드돌고래)는 나미비아 해안과 남아프리카 서부 해안에서 발견되는 작은 돌고래의 일종이다. 머리코돌고래, 칠레돌고래, 헥토르돌고래와 함께 흑백돌고래속에 포함된다.
하비사이드돌고래(Cephalorhynchus heavisidii, 영어: Haviside's dolphin ) 또는 히비사이드돌고래(Heaviside's Dolphin, 헤비사이드돌고래)는 나미비아 해안과 남아프리카 서부 해안에서 발견되는 작은 돌고래의 일종이다. 머리코돌고래, 칠레돌고래, 헥토르돌고래와 함께 흑백돌고래속에 포함된다.
