If dolphins weren’t such a$$holes, they would gently cradle the octopus like a kitten, stroking its mantle and respecting the cephalopod’s amazing intellect. But who are we kidding! This is a dolphin we’re talking about, and marine mammal researchers have found that dolphins “shake and toss” cephalopods like a dog tearing apart his favorite chew toy:

Why is this dolphin such an a$$hole to the octopus? Probably because cephalopods are yummy but dangerous food – they’re smart and sucker-y, and dolphins run the risk of *suffocation* if the octopus isn’t fully torn apart and incapacitated before meal time. As Sprogis et al. (2017) found, death by octopus tentacle is surprisingly common:

It is apparent that octopus handling is a risky behavior, as within our study area a known adult male stranded and a necropsy confirmed the cause of death was from suffocation from a large 2.1 kg octopus.1 The dolphin had attempted to swallow the octopus, however, the octopus was found almost intact, with the head and the mantle of the octopus in the dolphin’s stomach and the 1.3 m long arms separated from the head and extending out of its mouth.1 Similarly, another T. aduncus [dolphin] died from suspected asphyxiation due to an octopus lodged in its mouth and pharynx approximately 140 km north of our study area (Shoalwater Bay Islands Marine Park).2 In these two cases, the dolphins may not have processed the octopus sufficiently by shaking and tossing it to ensure the arm’s reflex withdrawal responses were inactive. Octopus arms have a defensive response, as their receptors can detect stimuli that cause damage to their tissues (Hague et al. 2013). These receptors allow octopus arms to continue reacting even after the arms have been detached from the head, allowing the arms to coordinate a reflex withdrawal response (Hague et al. 2013). Dolphins must therefore process the octopus sufficiently to reduce the arms reflex withdrawal response and limit their suckers adhering to them, which otherwise would make them difficult to swallow.

So mad props to all the octopuses out there, for fighting the good fight against dolphins (and sometimes winning!)

Here’s the frame-by-frame photo in all its glory (Figure 1 from the below paper):

Reference:

Sprogis KR, Raudino HC, Hocking D, Bejder L (2017) Complex prey handling of octopus by bottlenose dolphins (Tursiops aduncus), Marine Mammal Science, doi: 10.1111/mms.12405

The post Reason 5,879 why dolphins are a$$holes: Octopus “handling” first appeared on Deep Sea News.

Like seashells but are sick of social media?  Hate Facebook but need a hearty dose of marine invertebrates?  Want a bigger malacological meal rather than tiny tidbits of mollusk-based science? Do not worry, you can get all of the “Malacology Monday” posts from the Deep Sea News Facebook page right here on the official DSN website in a tidy & convenient monthly digest without submitting to The F-Book. Here’s what happened last month:

Malacology Monday starts big, really big.
Syrinx auranus, alternately the Australian Trumpet, the Golden Trumpet, and the False Trumpet is the world’s largest living shelled gastropod. This snail is rumored to reach lengths of up to a meter long, but research by members of Deep Sea News can only verify the largest as 72.2 cm (2.36 feet). This specimen from Indonesia is merely 58.2 cm, still nearly two feet in length. What does a snail this size eat? These carnivores tackle large polycheate worms that may grow over a meter in length.

Cloth of Gold, Cloth of…Murder!
In a 1972 episode of Hawaii Five-0, this species of marine snail was used as a murder weapon by a grieving father avenging the death of his daughter at the hands of seedy pornographers. While cone shells have a specialized harpoon & hypodermic needle-like apparatus to deliver toxins to kill their prey, most species are relatively harmless to humans. But some cone species, like the Cloth of Gold, or Textile Cone (Conus textile), can potentially deliver a fatally paralyzing dose of conotoxin to a person handling a live one. However, death can be quite slow, unlike the near-instantaneous demise depicted by those lowlife criminal scum. But not wanting to get nabbed by McGarrett, the mollusk-wielding murderer then turns the venomous gastropod on himself, and the scene fades, with his lifeless body sinking below the placid Oahu waters. Cue the 5-0 theme music…

Bulbous Bling
The Golden Cowrie (Lyncina aurantium) once adorned the kings of Melanesia, and were used as status symbols and units of trade. Their simple beauty and apparent rarity later made them highly sought by museums and private collectors alike, with the shells fetching hundreds of dollars each. It was their cryptic nature and inaccessibility that kept this species safe for a while. Once it was discovered that they were nocturnal, and inhabited the deeper outer reefs from 30-40 meters, they became targeted for the international shell trade. In in some areas, especially smaller islands in the Philippines, specialized Golden Cowrie divers collected them by the hundreds, driving their prices down yet causing local populations of Golden Cowries to plummet. Conservation and management plans are being considered in some areas of the southwest Pacific and Indian Ocean range, but so little is known about their biology that current management plans may not be effective.

Ceremonial Conch
The rather unremarkable looking shell below is actually quite remarkable in two ways. The incredibly thick shell of the Eastern Pacific Giant Conch (Lobatus galeatus) makes it one of the heaviest marine gastropods for its size. But this particular specimen had its spire cut off and made into a pututo, a ceremonial trumpet, and was found in a burial chamber of a lower class member of the Chimu culture of the north-central coast of Peru, about 1300 A.D. Higher-class people often had ornately-carved shells, sometimes with inlays of gems, as part of their burial offerings. The Giant Conch on the right from the Brooklyn Museum is from the older Chavin culture of Peru (about 300 BC) and shows a carving of a man blowing a conch as part of a ceremonial ritual.
All photos, unless otherwise noted, are by Douglas J. Long/Deep Sea News.

The post Malacology Monthly: Pilot Episode first appeared on Deep Sea News.