Newsflash:

Bats can swim

And are surprisingly good at it

Bats are capable of swimming in stressful situations if the need arises

Some species, such as those belonging to the genus Pteropus (flying foxes), have been known to brave the water to secure a meal#BatStroke pic.twitter.com/ulALyPM1yI

— Laurel Coons (@LaurelCoons) November 11, 2018

And there is of course the Great Fishing Bat. Amazing video here of its impressive catching capabilities. Many apologies for the over-the-top narration.

The post Holy Swimming Bats first appeared on Deep Sea News.

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.

The broadclub cuttlefish (Sepia latimanus) occurs all over coral reefs across the Indo-Pacific oceans.  In August of 2013 on a reef slope of the coast of Okinawa, Yasumuro and colleagues observed groups of 2-9 members comprised of individuals of similar body sizes.  The groups gently and continuously changed in their shapes between clusters and lines.  The cuttlefish synchronized their movements, equally space themselves, and oriented in a similar direction. In other words, they were schooling.  In larger schools, approximately half the cuttlefish would look in an opposite direction.  They were sort of hipster squid looking in the opposite direction before it was cool. Interestingly, bigger cuttlefish were followed by smaller cuttlefish.  Yet overall most of the cuttlefish were small to moderate sizes.  Larger and potentially crotchety adults never schooled.

Why the schooling?  Protection?  The schools all exhibited hunting behaviors.  Schools were either pursuing prey with rapid swimming, first and second arm pairs raised or extended, and finally tentacles ejected form the tips of arms to strike prey.  The schools also lured with individuals swimming with the first arm pair raised and swaying left to right to attract prey while simultaneously darkening the second arm pair tips while waggling the third arm pairs.  Yes its a complicated dance.  The schools may serve as hunting parties that can find and capture food more easily likes squishy, aquatic lions on the savannah.

So now that we know cuttlefish school, we need a name for the collective unit of cuttlefish.  I personally have always favored a squadron of squid over a school of squid.  Post your creative names in the comments below.

Yasumuro, H., Nakatsuru, S., & Ikeda, Y. (2015). Cuttlefish can school in the field Marine Biology, 162 (4), 763-771 DOI: 10.1007/s00227-015-2622-z

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The image of a seal (those goofy ball-on-the-nose guys!) mounting a penguin (those dapper black and white gents with the endearing waddle) is so absurd as to be ostensibly hilarious, until you really think about what’s happening here, and then it’s not funny at all, just disturbing and fascinating.  To start with, an adult fur seal is much larger and heavier than a king penguin and there’s a good likelihood that breathing of the penguin could be compromised from the weight of their attacker.  But it gets worse because, like other pinnipeds, fur seals have a baculum or penis bone, which increases the degree of trauma that might result from a successful penetration.  The gender of the hapless victim penguin (which was unknown for the reported cases and is hard to tell externally), would not really matter either because both male and female penguins have a cloaca or common opening that serves for solid and liquid waste disposal and also as the sexual portal of entry for normal carnal relations.  I don’t know much about penguin intelligence or cognitive ability, but we should at least consider the possibility that this is psychologically traumatic for the penguin.  Perhaps the ultimate moment of pause, though, comes when you read the researcher’s observation that in one of the instances, when the fur seal was finished raping the penguin, he killed it and ate it.  That’s just brutal.

Why is this happening?  The behaviour seems confined to sub-adult male fur seals and the researchers speculate that it may result from sexual frustration.  Why then would a fur seal have blue balls? Probably because the dominant adult male in the colony is preventing them from mating with his harem of ten or more females.  Fur seals are one of those pinniped species that has a “beach master” like this, so the social structure of a seal colony may predispose sub-adult males to this sort of behaviour.  That’s consistent with other cases of (to use a heteronormative phrase) aberrant sexual behaviour in marine mammals, such as long term homosexual pairing in adult dolphins, blowhole sex and inter-species sexual aggression and rape between dolphin species.  As one marine mammal biologist I spoke to put it, it appears that opportunities for apparently aberrant behaviours increase with increasing social complexity of the offending species.  In this case, the penguins are in the wrong place at the wrong time and of the wrong approximate size and end up bearing the brunt of frustrated sub-adult seals.  What makes this case so extraordinary is the giant taxonomic gulf between the two species; it’s one thing for a bottlenose dolphin to rape a spotted dolphin, but it’s another thing altogether for a mammal to rape a bird.  It’s probably only possible because this particular bird is flightless and not all that formidable an opponent while on land.

One of the more interesting aspects of this behaviour is its potential role in the ecology of infectious disease (forgive me, but I come from an animal health background and when you’ve got a hammer, everything looks like a nail!).  In one published example, bottlenose dolphins have problems with malignant oral and genital cancers that are caused by a papilloma virus and are sexually transmitted by the oral-genital contact that is common in the mating system of dolphins.  When I look at the images of the seal raping the penguin, I see extraordinary behaviour, but I also see the raw material for the evolution of “host switching”, the process whereby pathogens and parasites can effect a jump from one host species to another.  In this case it’s not a jump between species, but potentially between classes of vertebrates, and those opportunities may not come along all that often.  So, beyond the immediate morbidity (and in one observed case, mortality) of this behaviour, it will be interesting to see if any long term changes to the health status of penguins (or fur seals, for that matter) in this population occur in the future.  In the meantime it remains one of the more extraordinary bits of marine animal behaviour I have ever seen described.

Cited:

William A. Haddad, Ryan R. Reisinger, Tristan Scott, Marthán N. Bester, P. J. Nico de Bruyn (2014) Multiple occurrences of king penguin (Aptenodytes patagonicus) sexual harassment by Antarctic fur seals (Arctocephalus gazella).  Polar Biology. 10.1007/s00300-014-1618-3

Bossart G.D. (2007) Emerging Diseases in Marine Mammals: from Dolphins to Manatees. Microbe 2: 544-549

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Luckily those aggregations are random at best and behaviors aren’t coordinated…

This just in…the nocturnal foraging behavior of Humboldt Squids is coordinated.

Between 2007 and 2011, Kelly Benoit-Bird and William Gilly tracked both schools and individuals of Dosidicus gigas with sonar in the Gulf of California with some startling findings.   Two types of aggregations were seen: extremely dense groups in which individual squid could not be acoustically detected and loose but coordinated groups of followed parallel paths.

At night, individual and groups of up to 40 Humboldt Squid swam spirally upward at ~5 miles per hour from a school likely to prey upon fish.  Benoit-Bird and Gilly documented 103, 763 occurrences of this swim pattern.  Upon reaching one of the vertices of the spiral, individual squids would swim back and forth repetitively before continuing spiraling upward.

Movement in subgroups of squids were both coordinated in horizontally and vertically, i.e. depth, in the water column.  As noted by the authors, “The resulting groups of tracks look like interwoven multiple helices anchored at their vertices by bouts of presumed feeding.” Individual squids in the subgroups would swim a very similar spiral pattern but would spaces themselves out vertically and regularly. Adjacent squids maintained at least a distance of ~10 inches and on average ~3 feet.

Interestingly, the greater the size difference between two squid the greater the distance between them.  Why? It’s likely high levels of cannibalism, with smaller individuals being more prone to cannibalism by larger ones, helps squids remember to keep their distance.

I take more comfort not less in knowing that Diablo Rojo coordinate schooling efforts.  This implies some level of intelligence that may allow me to negotiate with them for my life before one of them consumes my brains. O’ wait that’s zombies…damn.

The post Coordinated Hunting in Red Devils first appeared on Deep Sea News.

Quirky, sheepish, fun-loving, lethargic, energetic, aloof, courageous, sensitive

You might invoke these words to describe your friends and family.  Indeed, you recognize them all by their distinctive personalities.  You may even use these terms to describe your beloved dog or cat.  But it is hard to imagine talking about an invertebrate and describing their personality. Although, I admit I do find sponges a bit aloof. That may be more me than them.

Anemones are not exactly a top pick when it comes to choosing an invertebrate with personality.  Like most, you would probably pick a cephalopod.  Rightly so given the large and complex brains of cephalopods compared to other invertebrates.  The brain to body weight ratio is higher for cephalopods than any other invertebrate. Cephalopods probably also have more personality than some dogs, especially my former roommate’s dog who only slept and ate cat poop. There is more than ample neural fodder in cephalopods for some individuality.

But an anemone? Please!  The nervous system is not centralized, i.e. no brain.  Anemones do not possesses any specialized sense organs. The nerves they possess are among the simplest in the animal kingdom.  Anemones are just a few specialized cell types from being an aloof but otherwise nondescript sponge.  Sorry sponges.

Personality is when an individual expresses a consistently different behavior despite the situation or time compared to other individuals.  And despite their rudimentary neural systems, anemones have personalities.  When disturbed, anemones will display a startle response in which they will retract their tentacles and cover their oral opening.  Mark Briffa and Julie Greenaway shot 3 tablespoons of water at the anemone Actinia equina, repeatedly, to illicit this startle response.  Individual anemones were consistent in the duration of their startle responses, from slow to quick, among trials.  An individual anemone taking 200 seconds to retract their tentacles in the first trial would, give or take a few seconds, take the same time in a second and third trial. Individual anemone behavior was also consistent despite variation of the environment around them, in this case water temperature.

However being too much of individual can be a bad thing.  Schools of small fish and herds of hoofed grazers necessitate the lack of individual behavior for group good.  Well, kind of.  The culmination of individual behaviors can actually come together to form complex group behaviors and self organize.  But these self-organized systems are thought to be sensitive to varying personalities among individuals.  For example, individual variability in ant movement can reduce the colony’s foraging efficiency.

Among snails of the intertidal, desiccation is a major concern during times of low tide.  One way to prevent desiccation is to seek shelter in a crevasse, among a group, or both [see the great photo here].  Or you could evolve into a subtidal snail but will ignore that route for now.  But how do these snail collectives form?  Do snails communicate with each other with complex clicking sounds that says we’ll be meeting at 2 clicks west at 0930 hours?  Not likely.  Groups form by chance but are regulated by three rules.  1. Snails move around randomly can choose to stop and aggregate when they encounter another snail. 2. Snails can choose to stop when they encounter a crevice. 3. They can follow mucus trails of other snails.  Thus large aggregations are likely to occur at the intersections of mucus trails, crevices, or any point that slows the progress of a lead snail.  All hail the snail leader!

During hot days you would expect snail behavior to change from cooler days. Like me when the temperature rises and the rock surface dries, snails spend less time moving.  And even though larger aggregations are more advantageous on hotter days, aggregation are expected to be smaller because of the reduced time to congregate.  This would obviously be sub-optimal self-organization.  In simple computer simulations conducted by Richard Stafford and colleagues this is exactly what happens. Smaller aggregations occur on hotter days. Likewise, in simplistic experiments on flat marble slabs where snails are allowed to roam and aggregate freely, smaller aggregations occur on hotter days.

However, in the real world on hot days snails form clusters the same size as cold days.  This appears in part because the surface complexity of rocks and various microhabitats afforded by crevasses, mitigates the changes in individual snail behaviors.    Thus in the natural world, interactions among individuals occur on a backdrop of environmental complexity which produces self-organized systems insensitive to the individual behavior.  In other words, the group good can prevail against individual personality as long as world is complicated.

Thus from snails and anemones we can take home a bit of wisdom.  Be yourself and let your freak flag fly, because in our complicated world the good will prevail. Or maybe not.

Stafford, R., Williams, G., & Davies, M. (2011). Robustness of Self-Organised Systems to Changes in Behaviour: An Example from Real and Simulated Self-Organised Snail Aggregations PLoS ONE, 6 (7) DOI: 10.1371/journal.pone.0022743

Briffa, M., & Greenaway, J. (2011). High In Situ Repeatability of Behaviour Indicates Animal Personality in the Beadlet Anemone Actinia equina (Cnidaria) PLoS ONE, 6 (7) DOI: 10.1371/journal.pone.0021963

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Hat tip to my brother. More info about this video at Treehugger. Make sure to turn on HD.

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