#Stenella longirostris

[namu-the-orca]

trick or treat!!! 🐋

We're almost a month along but the tricking and treating continues! Thank you for your message ♥ For you another ceta study: a spinner dolphin leaping in front of a dramatic sky.

Once again, the original - gorgeous - photo is from Inaturalist shared under a CC-BY license. The colours and reflections really caught my eye! I spent way too long on this but am really pleased with the result.

I do sometimes wonder how much I learn from these; I'm not sure if I really get a better grasp of painting water/reflections when copying a photo with water/reflections. Like, I'm just repeating what I see, not really getting it. Does anyone have tips for this? Especially when it comes to backgrounds, because those are my weakness.

Either way they are really fun to do in between commission work, and I hope you like it too!

[whats-in-a-sentence]

One animal might insert the tip of its beak into the other's genitals or perhaps just use its lower jaw to penetrate and stimulate his or her partner.

"Biological Exuberance: Animal Homosexuality and Natural Diversity" - Bruce Bagemihl

[tenth-sentence]

The lower animal may also turn on its side or rotate belly up during this activity.

"Biological Exuberance: Animal Homosexuality and Natural Diversity" - Bruce Bagemihl

[oh-dear-so-queer]

Spinner Dolphins seem to be more uniformly bisexual without extensive periods of exclusive homosexuality, often alternating between same-sex and opposite-sex interactions in quick succession (this sort of concurrent bisexuality has also been observed in Bottlenose and Atlantic Spotted Dolphins).

"Biological Exuberance: Animal Homosexuality and Natural Diversity" - Bruce Bagemihl

[inatungulates]

Gray's spinner dolphin "Stenella" longirostris longirostris

Observed by tonyshao7, CC BY-NC-ND

[writing--references]

Spinner dolphins (Stenella longirostris)

[keynewssuriname]

Surinaams gebied wordt ook erkend als belangrijk zeezoogdierengebeid

De Suriname rivier is een van de 5 gebieden die onlangs erkend zijn als belangrijk zeezoogdierengebied. Dat laat de Green Heritage Fund weten in haar berichtgeving. In totaal zijn er 33 nieuwe Important Marine Mammal Areas (IMMA's) of ook wel belangrijke zeezoogdierengebieden geïdentificeerd en op de kaart geplaatst in de Zuidwest Atlantische Oceaan vanaf de Guianas, ten noorden van de Braziliaanse Amazone, tot het puntje van Tierra del Fuego, Argentinië. Dit is het eindresultaat van een proces van een jaar, met een intensieve vijfdaagse workshop van wetenschappers afgelopen december waarin gegevens over kandidaat-IMMA's werden beoordeeld en gepresenteerd, die vervolgens voor peer review werden ingediend. Naast de 33 nieuw goedgekeurde IMMA's, hebben 5 gebieden de status van Area of Interest (AoI) gekregen. IMMA's worden gedefinieerd als afzonderlijke delen van een habitat die belangrijk zijn voor zeezoogdierensoorten en die potentie hebben om te worden afgebakend en beheerd voor bescherming. Het zijn geen bij wet vastgestelde aanwijzingen, maar onafhankelijke beoordelingen die zijn peer-reviewed op basis van een reeks criteria die met data worden onderbouwd. "Wij verwelkomen deze wereldwijde erkenning van onze iconische mariene rijkdommen die voor de oostkust van Zuid-Amerika liggen", zei José Truda Palazzo, jr. van het Humpback Whale Institute, dat de workshop in december organiseerde in Praia do Forte, Brazilië. De opmerkelijke habitats van de regio voor zeezoogdieren omvatten onder andere de Abrolhos Bank en de Fernando de Noronha-eilanden voor Brazilië, evenals de Straat van Magellan en de Patagonische wateren van Península Valdés in Argentinië en de Suriname Rivier in Paramaribo. “De afgelopen decennia hebben we ons onderzoek naar de zeldzame, endemische, bedreigde zeezoogdieren in de regio geïntensiveerd,” voegde Miguel Iñíguez toe van Fundación Cethus en Whale and Dolphin Conservation, uit Argentinië. De Zuidwest-Atlantische Oceaan (SWATLO) heeft zuidkapers (Eubalaena australis), bultruggen (Megaptera novaeangliae) en Noordse vinvissen (Balaenoptera borealis), waarvan sommige reizen van Antarctica naar deze regio. Naast de veel voorkomende langsnuitdolfijn (Stenella longirostris) en gewone tuimelaars (Tursiops truncatus), zijn er soorten die endemisch zijn in het gebied, waaronder de Commerson-dolfijn (Cephalorhynchus commersonii ssp. commersonii), de kwetsbare franciscana (Pontoporia blainvillei), de kwetsbare Lahille's tuimelaar (Tursiops truncatus ssp. gephyreus) en de bijna bedreigde Guiana-dolfijn (Sotalia guianensis). De kwetsbare West-Indische lamantijn (Trichechus manatus) wordt gevonden langs de kusten van de Guianas en het noordoosten van Brazilië. De vijfdaagse IMMA-workshop, gehouden in Praia do Forte, Brazilië, in december 2022, werd georganiseerd en aangestuurd door het IMMA-secretariaat van de IUCN Task Force on Marine Mammal Protected Areas, en gehost door het Braziliaanse Instituto Baleia Jubarte (Humpback Whale Institute). De 31 deelnemers aan de workshop, bestaande uit de beste wetenschappers op het gebied van zeezoogdieren, begonnen met het in overweging nemen van 112 voorlopige interessegebieden (proposed Areas of Interest – pAoI). De pAoI die werden geselecteerd om door te gaan naar kandidaat-IMMA's, werden onderbouwd met tekst bij de verschillende criteria die was gebaseerd op wetenschappelijke feiten. Zij werden verder gedetailleerd in kaart gebracht samen met een sterke motivering voor de gekozen grenzen. De peer review en de kaarten van deze gebieden zijn nu voltooid. De resultaten van de Braziliaanse workshop betekenen dat er nu wereldwijd 242 IMMA's zijn, elk met onderliggende documentatie, kaarten en andere achtergrondinformatie in de IMMA e-Atlas. Volgens de medevoorzitters van de Task Force, Giuseppe Notarbartolo di Sciara en Erich Hoyt, heeft het IMMA-team samen met 267 wetenschappers op het gebied van zeezoogdieren nu 72% van de oceaan onderzocht, waarvan 13% IMMA's zijn. Zij hopen in de komende 4-5 jaar de tien jaar durende wereldwijde wetenschappelijke beoordeling van de habitats van de 133 zeezoogdierensoorten te voltooien. Ondertussen gaan de IMMA-werkzaamheden door in de Noordoost-Atlantische Oceaan waarvan de eindresultaten worden verwacht begin 2024 en de Noordwest-Atlantische Oceaan en het Caribisch gebied, met een workshop gepland voor mei 2024 en de definitieve resultaten uiterlijk begin 2025. Read the full article

[oceansoftheworld]

(Photo by Sam Nuttmann)

Hawaiian spinner dolphin

[fuckyeahaquaria]

Spinner Dolphin |  Stenella longirostris

Spinner dolphins are best known for their above-water displays of leaping and spinning several times on their body axis. Leaps can often be done in a series with as many as 14 leaps in a row. Spinner dolphins are sometimes found in associations with bottlenose dolphins or humpback whales in Hawaii, which may benefit one or both species.

[namu-the-orca]

A posse of proper ‘phins And another set of illustrations from last year. This time the “proper” dolphins - not too small, a regular dorsal fin, a good beak. Only the Risso’s is a bit out of line with their cute potheads but otherwise he was all alone. I had lots of fun with all of these. Spinners and Pantropcal spotted dolphin are a delight to draw always. This Pantropical spotted is from the Indian ocean, which tend to have fine black spots and very few white spots. The rough-toothed dolphin gave me some trouble - they’ve such odd proportions they’re hard to really nail down. I still don’t think he fully looks right, but that’s for a different illustration.

The common dolphins on top are very interesting to me: a good example of the diversity found within the single species of Delphinus delphis. Both are forms living around Southern Africa. The “longer beaked” form is larger, more elegant, and has gorgeous clear markings. They live off the Southeast coast, relatively close to shore. The “shorter beaked” form lives more to the west, in offshore waters. They are stouter and often with slightly vaguer markings. One day I’d love to see a study done on all the African forms of short-beaked common dolphins, they are so fascinating. If you move further up the west coast, around Angola, you’ll find a really strange form which is super dark and oddly proportioned. Wonder what’s up with those.

The Indian Ocean humpback dolphin is also an oddball, and a first for me. Love their cute faces and unique body shape. Not just the hump-back but also that strongly keeled peduncle. I hope you’ll enjoy them too!

[whats-in-a-sentence]

Bottlenose Dolphins have a highly developed social system characterized by four basic social units: mother-calf pairs, groups of adolescents (often male-only, or with a preponderance of males), bands of up to a dozen adult females and their young, and adult males in pair-bonds (and less commonly, on their own). Spinner Dolphins may have a more fluid social organization, although coalitions of males can sometimes be recognized, as well as schools of a thousand or more individuals.

"Biological Exuberance: Animal Homosexuality and Natural Diversity" - Bruce Bagemihl

[chilirasbora]

Spinner dolphin | Stenella longirostris

X

[cypherdecypher]

Animal of the Day!

Spinner Dolphin (Stenella longirostris)

(Photo by Julian Tyne)

Conservation Status- Data deficient (Data inadequate to determine a threat category)

Habitat- Pacific Ocean; Atlantic Ocean

Size (Weight/Length)- 77.1 kg; 234.6 cm

Diet- Fish; Squid

Cool Facts- Spinner dolphins make bottlenose dolphins look basic. Like bottlenose dolphins, spinner pods are constantly on the move without a set territory. Unlike bottlenoses, spinner dolphins live in pods of a few dozen to a few thousand. These massive pods will dive up to 300 meters searching for fish and squid. One of the most baffling behaviors spinners exhibit is jumping from the water. They leap from the water and spin in a corkscrew. Scientists believe that this jumping may be a type of language for the dolphins or it might just be for fun.

Rating- 12/10 (You spin me right round, right round.)

[inatungulates]

Gray's spinner dolphin "Stenella" longirostris longirostris

Observed by nathancook, CC BY-NC

Features for recognizing the bridled dolphins, pt. 4: "typical" spinner dolphins

Apart from the Eastern Tropical Pacific, spinner dolphins throughout the rest of their pantropical range appear as more conventional bridled dolphins.

Useful features of pattern for ID:

"Three-tiered" coloration: a dark dorsal cape, mid-tone on the sides, and pale underside. This style of coloration is pretty typical for delphinids, but spinner dolphins are probably the most clear-cut example of it, giving them something of a "layer cake" appearance.

The dorsal cape may arch from behind the eye to dip down again below the dorsal fin, as in these individuals, or it may be fairly level.

The pale grey, white, or pinkish ventral coloration is usually crisply-demarcated from the medium-grey thoracic coloration, and often extends up above the dark pectoral flippers.

The thin lipline and beak tip are very dark.

There is usually not a prominent facial mask, but the thin lines of the bridle, running from the eye to the base of the rostrum and from the eye of the base of the flipper, are typically crisp.

Useful features of body shape for ID:

The rostrum is extremely long and thin. Apart from some forms (or species...) of common dolphin Delphinus delphis, spinners have the most elongate rostra of all delphinids, and the most teeth of any mammal.

Dorsal fin is erect and essentially triangular; unlike most dolphins it is only faintly falcate, if at all, and approaching their Eastern Tropical Pacific relatives may sometimes have a gentle forward cant. The dorsal fin is proportionally larger than in the ETP spinners, though.

These are overall fairly small, slightly-built, compact dolphins.

[writing--references]

Hawaiian Spinner Dolphins (Stenella longirostris longirostris), Big Island, Hawaii.

Spinner dolphins of Hawaii are nocturnal feeders and forage in deep scattering layers, which contain many species. Off Oahu, Hawaii, spinner dolphins forage at night and cooperatively herd their prey into highly dense patches. They swim around the prey in a circle and a pair may swim through the circle to make a catch. Spinner dolphins are in turn preyed on by sharks, orcas, false killer whales, pygmy killer whales, and short-finned pilot whales.

Spinner dolphins in Hawaii receive multiple daily visits to their near-shore resting grounds, with boats taking people out daily to snorkel and interact with the local dolphin population. Such activities are increasingly coming under criticism on the grounds of possible harm to the dolphins, and efforts are being made both to educate the public in order to minimize human impact on the dolphins, and to bring in regulations to govern these activities.