Cephalopod Sex and Reproduction

DWhatley

Kraken
Staff member
Moderator
Joined
Sep 4, 2006
Messages
20,408
Reaction score
1,712
Location
Gainesville, GA
Role of olfaction in Octopus vulgaris reproduction
Gianluca Polese , Carla Bertapelle , Anna Di Cosmo 2014 (subscription)

Abstract
The olfactory system in any animal is the primary sensory system that responds to chemical stimuli emanating from a distant source. In aquatic animals “Odours” are molecules in solution that guide them to locate food, partners, nesting sites, and dangers to avoid. Fish, crustaceans and aquatic molluscs possess sensory systems that have anatomical similarities to the olfactory systems of land-based animals. Molluscs are a large group of aquatic and terrestrial animals that rely heavily on chemical communication with a generally dispersed sense of touch and chemical sensitivity. Cephalopods, the smallest class among extant marine molluscs, are predators with high visual capability and well developed vestibular, auditory, and tactile systems. Nevertheless they possess a well developed olfactory organ, but to date almost nothing is known about the mechanisms, functions and modulation of this chemosensory structure in octopods. Cephalopods brains are the largest of all invertebrate brains and across molluscs show the highest degree of centralization. The reproductive behaviour of Octopus vulgaris is under the control of a complex set of signal molecules such as neuropeptides, neurotransmitters and sex steroids that guide the behaviour from the level of individuals in evaluating mates, to stimulating or deterring copulation, to sperm-egg chemical signalling that promotes fertilization. These signals are intercepted by the olfactory organs and integrated in the olfactory lobes in the central nervous system. In this context we propose a model in which the olfactory organ and the olfactory lobe of Octopus vulgaris could represent the on-off switch between food intake and reproduction.
Related findings of olfactory system effecting sexual maturation:

Control of GnRH expression in the olfactory lobe of Octopus vulgaris (pdf)

The presence of APGWamide in Octopus vulgaris: a possible role in the reproductive behavior
 
Last edited:

DWhatley

Kraken
Staff member
Moderator
Joined
Sep 4, 2006
Messages
20,408
Reaction score
1,712
Location
Gainesville, GA
SQUID
Threat of Being Eaten Doesn’t Deter Dumpling Squid From Sex

... To see how the squid behave in the face of danger, researchers from the University of Melbourne collected 15 pairs of wild dumpling squid from the waters off Victoria, Australia. They also scooped up 15 of one the squid’s most common natural predators, a type of fish called the sand flathead. They put each squid pair into separate containers, then exposed them to various kinky scenarios, including introducing a predator before the squid began to mate, during mating and an hour after mating. The researchers noted any defensive behaviors, such as blowing out a cloud of ink to mask their presence or jetting away by quickly ejecting water out of the body. ...
 

DWhatley

Kraken
Staff member
Moderator
Joined
Sep 4, 2006
Messages
20,408
Reaction score
1,712
Location
Gainesville, GA
How Male Octopuses Avoid Being Eaten by Hungry females

Nice layperson's article discussing numerous mating habits of octopuses. Do note that the two siphon statement (as well as using the siphon at all in mating) needs correction but it covers the subject rather well.


Presented by
Katherine Harmon Courage

Male octopuses have a big problem: female octopuses. Each male wants to mate and pass on his genes to a new generation. The trouble is, the female is often larger and hungrier than he is, so there is a constant risk that, instead of mating, the female will strangle him and eat him.

The males have a host of tricks to survive the mating process. Some of them can quite literally mate at arm's length. Others sneak into a female's den disguised as another gal, or sacrifice their entire mating arm to the female and then make a hasty retreat.

It's all very macabre. It's also a paradox. Octopuses are some of the most antisocial, unfriendly animals alive. Yet their bodies have evolved in such a way that they must mate in the most intimate way possible: the male has to insert his sperm directly into the female's body using one of his arms. The resulting mating practices are not just a curiosity: they are a window onto how octopuses have evolved into the creatures they are today.

Wunderpus octopuses (Wunderpus photogenicus) mating (Credit: Roy Caldwell)

Octopuses and their close cousins the squid all belong to a group of animals called cephalopods. Both are actually molluscs, making them close relatives of oysters and limpets, but they have lost their shells.

Octopuses tend to be profoundly antagonistic towards each other. Unlike gregarious animals like dolphins, they appear to see their own kind primarily as competition, and sometimes food.

There's always the threat of cannibalism
Squid, which are downright social by comparison, mate in a distinctly unromantic way. A male squid swims by and deposits sperm in one quick move outside of the female's body. She can decide later whether to accept it.

But not so the octopus. "Octopus mating is definitely different than other cephalopods," says marine biologist Jean Boal of Millersville University in Pennsylvania. The male must deposit his sperm inside the female's body, at the risk of his life.

"There's always the threat of cannibalism," says Richard Ross of the California Academy of Science's Steinhart Aquarium.






Two day octopuses (Octopus cyanea) mating (Credit: Georgette Douwma / NPL)

We don't know how often female octopuses eat the males, but Christine Huffard of the Monterey Bay Aquarium Research Institute in California has seen it happen many times.

She strangled him and took him back to her den to feed on
In one instance, she and her colleagues observed two day octopuses mating on a reef in Indonesia. After about 15 minutes of copulation, the female lunged and wrapped two arms around the male's bulbous body, his mantle. A few minutes later, the male was motionless. The female then carried the corpse to her den, where he presumably became dinner.

In another instance, researchers watched a large female day octopus off the coast of Micronesia. A small male mated with her a dozen times. But then the male went in for a 13th mating session, and the female turned on him. She strangled him and took him back to her den to feed on over the course of the next two days.

Sexual cannibalism does happen in nature - witness the male-eating praying mantis and black widow spiders - but strangulation during mating is a rarity, Ross says. It may not be all bad for the male, though.

As Huffard and her colleagues point out in a 2014 paper describing one of the male-eating incidents, the felled male probably managed to fertilize some of the female's eggs - accomplishing his life's mission despite his unfortunate demise. What's more, females generally make hundreds or even hundreds of thousands of eggs, so just one successful copulation can produce a vast number of offspring.

The male's main tool for this daunting endeavour is a specialized mating arm, known as the hectocotylus. When he is not engaged with a female, the mating arm works just like his other seven arms. It is able to bend, stretch and exert suction. But the mating arm also comes with extra bells and whistles.

For big species, mating can last at least half an hour
For one, it has a central groove. The male releases packets of sperm called spermatophores into this groove, for their journey to the female. The arm's tip is also equipped with erectile tissue, not unlike that found in the human penis, which provides stiffness that helps guide the arm into the female's body. The arm goes in through one of the two siphons on the female's mantle, which she also uses to breathe, expel waste and jet out water for swimming.

The destination for these spermatophores is the female's small oviducal gland, a sort of holding area. When she lays her eggs, which could be days or even months later, they will pass this area and be fertilised.

The male needs to keep his mating arm tip inside the female long enough to transfer at least one spermatophore, and preferably more. In some smaller species this might take just a couple minutes, says Jennifer Mather of the University of Lethbridge in Alberta, Canada. But for big species like the giant Pacific octopus, mating can last at least half an hour.

But being soft-bodied, they can't indulge for too long. "If you get all wrapped up in mating, you're very, very vulnerable to predators," says Mather.






Giant Pacific octopus (Enteroctopus dofleini) on the sea bed (Credit: Jeff Rotman / NPL)

As a general rule, it's the male octopuses that approach the females.Then the males tend to take one of two approaches in attempting insemination.

The first is a risky position called the "mount". "The male grabs onto the female's mantle with all his arms, and reaches into her mantle with his mating arm," says Huffard.

This style of mating tends to be more popular in species with shorter arms, says Huffard. Females of these species may be less likely to eat their mates. Possibly, species in which males are more likely to be devoured during sex have evolved longer arms, which would make mating a little safer for the males.

Algae octopuses (Abdopus aculeatus) mating (Credit: Roy Caldwell)

More cautious males opt for the "reach". "The male sits near the female and reaches over to her only with the mating arm," says Huffard.

This allows him to keep his distance. "The male will extend his arm as long as he can and try to accomplish the copulation from as far away as he can," says Boal.

The "reach" tactic is more common in octopuses with longer arms, which may be the ones where female cannibalism is more likely. An extra-long reach means that the male can stretch his arm into a resting female's den and mate with her without even venturing inside.






Male algae octopuses (Abdopus aculeatus) mate from a distance (Credit: Roy Caldwell)

The algae octopus is one such cautious mater. "Males have a very long mating arm," says Huffard. "They stretch this arm to twice its resting length when mating." Just to be on the safe side, "these males also frequently mate with females that are busy foraging for food". These females ought to be too busy to eat him.

The "reach" approach also keeps the male's other seven arms free, so he can defend himself if need be, says Ross. This may be why the coconut octopus practices distant sex.

The "reach" tactic might also be advantageous for the female. In theory, she could entertain two male suits at once, says Huffard: one in each siphon.

For male argonauts, mating costs an arm (Credit: David Shale / NPL)

In some species, male octopuses have moved beyond the "reach". They just give the female their spermatophore-loaded mating arm, and swim away to safety.

A detached mating arm might be a logistical necessity
Male argonaut octopuses are smaller than the females, and the male's hectocotylus simply stays intact inside the female's mantle "until the female is ready to use the sperm for fertilization", Mather says.

It was actually this behaviour that earned the hectocotylus its name. In the early 19th century the zoologist Georges Cuvier discovered strange foreign objects in female argonaut octopuses and thought they must be a type of parasitic worm. He called them Hectocotylus octopodis, and the name stuck.

For blanket octopuses, a detached mating arm might also be a logistical necessity. The females can be 2m long, while the males are just a few centimetres. So the male "removes the arm that carries the sperm, and the arm goes into the [female's] mantle cavity," says Ross. "That's a pretty extreme strategy to not get eaten."






Greater blue-ringed octopuses (Hapalochlaena lunulata) mating (Credit: Roy Caldwell)

But it's not all rough-and-tumble, strangulation and arm removal. Algae octopuses are slightly more tolerant of each other than most species, and as a result their mating behaviours are more nuanced.

They have even been known to disguise themselves as females
Males of this species have other males as well as females to fear when attempting to mate. The largest males often have the privilege of guarding a desirable female and mating with her repeatedly. Smaller males have no chance of driving them off, and they know it. "Males appear to alter their mating tactics, based on their local chances of winning fights with rivals," says Huffard.

The smaller males wait until a larger guarding male has left the den, then covertly mate with the female. As a result, they are called "sneaker" males. They have even been known to disguise themselves as females, hiding their hectocotylus to make a less threatening approach to a guarded female.

This sly tactic can occasionally backfire, as it did in an instance caught on film by Huffard. A sneaker male approached a burrow where he seemingly sensed a female was hiding. As he reached an arm in, an octopus emerged. But it was not the female: it was her guarding male. Unsurprisingly, this big male was not impressed by the sneaker male's attempt to insert a hectocotylus into his mantle. The small male only narrowly escaped the ensuing fight.

A giant Pacific octopus (Enteroctopus dofleini) (Credit: Brandon Cole / NPL)

These cunning tactics pale in comparison to the behaviour of one newly-discovered octopus species. The larger Pacific striped octopus has not yet been formally described. But its sexual habits break all the rules for octopuses.

They mate beak-to-beak
The larger Pacific striped octopus is one of the few known gregarious octopuses. These octopuses can live together, even in close quarters, without eating or otherwise maiming each other.

This tolerance carries through to their mating habits. "They mate beak-to-beak, mouthpart-to-mouthpart," says Ross, who has witnessed numerous mating sessions. This is bizarre, because octopuses' sharp and strong beaks are their most dangerous weapons.

In this unusual position, a pair of octopuses will spread their arms out together, so that the suckers seem to touch. "That's a really, really strange thing," says Ross.

A female lesser Pacific striped octopus (Octopus chierchiae) (Credit: Roy Caldwell)

The larger Pacific striped octopus has a close cousin, the imaginatively-named lesser Pacific striped octopus. These are much more typical. "The male jumps on top of [the female's] mantle, away from her arms," says Ross. "It's an amazingly quick movement, in case she's in a bad mood or something. Then they mate, and he moves away as fast as he can."

When octopuses mate there are 16 arms to keep track of
No one knows why the larger Pacific striped octopus is so much more sociable than other species. Its apparent oddity reminds us that we don't really understand octopus sex in general. Why would such a voracious, antisocial animal mate so intimately?

Perhaps, despite the scale of the sexual cannibalism, few enough males meet their doom at their mates' hands, er, arms - and enough of them manage to pass on sperm. If that's the case, there might not be much evolutionary pressure on the males to evolve a safer way to mate.

"No one's really worked all of this out," says Mather. That may be in part because only a handful of species have been studied so far. "We have a vague understanding of mating in about a dozen shallow-water octopuses," Huffard says. "That leaves over 275 shallow-water species to go, and all of the deep-water species." Those deep-water octopuses might hold evolutionary clues to what early octopus sex looked like.

It may be some time before we truly understand why octopuses have sex the way they do. Part of the problem is that they are extraordinarily difficult to study. There are the obvious problems that they live underwater and are masters of camouflage. But even more challenging, when octopuses do get together there are 16 arms to keep track of. "It's really difficult to see what's going on," says Ross.
 

mucktopus

Haliphron Atlanticus
Staff member
Moderator
Joined
Dec 31, 2003
Messages
523
Reaction score
52
Yeah I don't know where the two siphon (funnel) idea comes from. My guess is that people think that octopuses have two funnels because some octopus toys have two funnels. I think people model the toys based on photos, and many photos show the movable funnel, no matter which side the images is from
 

DWhatley

Kraken
Staff member
Moderator
Joined
Sep 4, 2006
Messages
20,408
Reaction score
1,712
Location
Gainesville, GA
Actually, she SHOULD know better as she (Harmon) has a journalist book out about cephs. I also don't know where the idea comes from that the siphon has anything to do with reproduction.
 

DWhatley

Kraken
Staff member
Moderator
Joined
Sep 4, 2006
Messages
20,408
Reaction score
1,712
Location
Gainesville, GA
Octopus
Distance chemoreception and the detection of conspecifics in Octopus bimaculoides

Matthew D. Walderon, Kevin J. Nolt, Robert E. Haas, Krista N. Prosser, Johanna B. Holm, Gregg T. Nagle, Jean G. Boal 2011 (full article)


Octopuses are solitary predators that typically use their arms to grope into crevices to find food. They detect odours on contact using chemosensory cells on their lips and suckers (Budelmann, 1996). They can also detect water-borne odours (distance chemoreception) using receptors in their olfactory organs (olfactory pits; Budelmann, Schipp & Boletzky, 1997). Behavioural experiments have demonstrated increased arousal (Boyle, 1983), activity (Boyle, 1986) and attraction (Chase & Wells, 1986;Lee, 1992) in response to food-related odours, but responses to odours of conspecifics have not previously been investigated. Chemical communication has been demonstrated previously in cephalopods, such as Nautilus (Basil et al., 2002), Loligo (Gilly & Lucero, 1992; Buresch et al., 2003; King, Adamo, & Hanlon, 2003) and Sepia (Boal, 1997; Boal & Marsh, 1998; Boal et al., 2010). Here we investigate behavioural evidence for detection and attraction to conspecific odours by Octopus.
 

DWhatley

Kraken
Staff member
Moderator
Joined
Sep 4, 2006
Messages
20,408
Reaction score
1,712
Location
Gainesville, GA
Octopus researcher a sucker for hard work
Interesting new research but no paper yet.

THE sex life of an octopus is the subject of a study by University of WA Ocean’s Institute-backed James Cook University researcher Peter Morse this summer.

“We want to know just how the females are choosing some males’ sperm over others, because there are often many fathers in any egg clutch,” Mr Morse (28) said.

Last summer, his traps for the cephalopods along the WA coast, including Cottesloe and South Fremantle, contributed to results published in the science journal Behaviour last month.

The venomous male southern blue-ringed octopus being studied is allocated about 50 sperm during its seven-month life.

Females store different males’ sperm in a gland behind their heads, before potentially deciding which to use to fertilise precious eggs, then they dig a burrow or hide to protect their young.

The mothers eventually die after protecting the eggs for two months, while the males die when they have exhausted their sperm.

“We also would like to know how the males seem to be aware of how much sperm the females are holding, and because they have a limited amount of sperm in a lifetime they seem to be regulating the amount they are using,” Mr Morse said.

His previous studies indicated males appear to be able gauge just how much sperm from their competitors are being held by the females and males change the amount of sperm they leave with a female, while ensuring they have enough left for mating with other females.

“They seem to strategically allocate their limited sperm,” Mr Morse said.

Last month, he started weekly collections from about 200 octopus traps 50m-100m offshore from South Fremantle power station, near to where he trapped more than 110 animals in Cockburn Sound a year ago.

”What we’re doing is verifying the behaviour indicated by our previous research that showed males mate to maximise retention of a limited amount of sperm,” Mr Morse said.

“We are trying to determine how the different times spent by a male mating with a female affects the pattern of fatherhood.”

The traps, which Mr Morse collects by snorkelling, should not be disturbed and have AIMS Research written on their buoys.
 

DWhatley

Kraken
Staff member
Moderator
Joined
Sep 4, 2006
Messages
20,408
Reaction score
1,712
Location
Gainesville, GA
Octopus - Mating Mimics
Published on Apr 3, 2013
These mimic octopus are known for impersonating other creatures ... this time they are just getting amorous! In this unique video you can see the mating struggle of the mimic octopus and also the hilarious reaction of our underwater cameraman - Christian Loader.
 

DWhatley

Kraken
Staff member
Moderator
Joined
Sep 4, 2006
Messages
20,408
Reaction score
1,712
Location
Gainesville, GA
SQUID
When should male squid prudently invest sperm?

Amy K. Hoopera,Benjamin J. Wegenera, Bob B.M. Wonga 2016 (subscription)

Ejaculate production can be costly and males are expected to prudently allocate this potentially limiting resource to higher quality females. However, relatively little is known about facultative sperm allocation in response to the quality distribution of sequentially encountered females, despite this being a more realistic scenario for males in many species. Here, we examined patterns of male investment in a squid, Sepiadarium austrinum, when presented sequentially with small versus large females. Owing to a positive size – fecundity relationship in this species, large and small females are expected to differ in terms of their perceived quality to males as potential mating partners. Yet, despite large sperm investment and significant variation in female quality, sperm investment was determined only by mating order, with males consistently decreasing sperm investment in second matings. These results highlight that, when mates are encountered sequentially rather than simultaneously, prudent sperm allocation may not occur when it is otherwise predicted.
 

mucktopus

Haliphron Atlanticus
Staff member
Moderator
Joined
Dec 31, 2003
Messages
523
Reaction score
52
Octopus researcher a sucker for hard work
Interesting new research but no paper yet.
Indeed Peter has been hard at work. The first paper from his PhD is out:

Morse, P., K.R. Zenger, M.I. McCormick, M.G. Meekan, & C.L. Huffard (2015) Nocturnal mating behaviour and dynamic male investment of copulation time in the southern blue-ringed octopus, Hapalochlaena maculosa (Cephalopoda: Octopodidae) Behaviour doi: 10.1163/1568539X-00003321 (28 pages)

If anyone would like to read it, send me your email address in a message, and I can pass along the pdf.
 

DWhatley

Kraken
Staff member
Moderator
Joined
Sep 4, 2006
Messages
20,408
Reaction score
1,712
Location
Gainesville, GA
Male copulatory behavior interrupts Japanese flying squid Todarodes pacificus female spawning activity
Pandey Puneeta, Dharmamony Vijai, Jun Yamamoto, Yasunori Sakurai 2016 Marine Ecology Subscription

ABSTRACT: Batch spawning, intermittent spawning and multiple spawning represent common reproductive strategies among cephalopods. These flexible spawning strategies are also common in fishes, and are thought to be a female trait that is programmed depending on environmental parameters. The ommastrephid squid Todarodes pacificus, being a terminal spawner, is considered to have a single spawning event, extruding one large egg mass and dying soon thereafter. Females that are interrupted by males exhibiting mating behavior, while extruding the egg mass, spawn multiple egg masses over the course of 2-3 d instead of dying soon after spawning the first egg mass. We demonstrate that male mating behavior causes ‘forced’ intermittent spawning by females (i.e. more than one spawning event). We hypothesize that in T. pacificus, some males use this strategy to mate with females unable to repel advances while spawning, thus providing the male with the opportunity to contribute sperm and enhance gene flow.
 

DWhatley

Kraken
Staff member
Moderator
Joined
Sep 4, 2006
Messages
20,408
Reaction score
1,712
Location
Gainesville, GA
Great octo sex talk!
Published on Jul 22, 2013
Dr. Janet Voight settles the eternal debate about the plural form of "octopus," and becomes my new favorite person.

Want more of Dr. Voight?! Check out her other videos and media appearances!
Podcasts
http://fieldmuseum.org/explore/multim...

http://fieldmuseum.org/explore/multim...

Expeditions
http://fieldmuseum.org/explore/past-r...

Partials - also see Field Revealed outtakes
http://fieldmuseum.org/explore/multim...
http://fieldmuseum.org/explore/multim...


Facebook: http://www.facebook.com/thebrainscoop

The Brain Scoop is hosted and written by:
Emily Graslie

Created By:
Hank Green

Directed, Edited, and Scored by:
Michael Aranda

Assistant Editor:
Stefan Chin

Thanks to Martina Šafusová, Diana Raynes, Barbara Velazquez, Hervé Saint Raymond, Alex Austin, Tony Chu, John-Alan Pascoe, and Seth Bergenholtz for taking the time to transcribe this episode! WOOOOOO
 

DWhatley

Kraken
Staff member
Moderator
Joined
Sep 4, 2006
Messages
20,408
Reaction score
1,712
Location
Gainesville, GA
Impact of cryptic female choice on insemination success: larger sized and longer copulating male squid ejaculate more, but females influence insemination success by removing spermatangia
Noriyosi Sato, Masa-aki Yoshida, akashi Kasugai 2016 (subscription Wiley)

Abstract
In polyandrous mating systems, sperm competition and cryptic female choice (CFC) are well recognised as post-copulatory evolutionary forces. However, it remains challenging to separate CFC from sperm competition and to estimate how much CFC influences insemination success because those processes usually occur inside the female's body. The Japanese pygmy squid, Idiosepius paradoxus, is an ideal species in which to separate CFC from sperm competition because sperm transfer by the male and sperm displacement by the female can be observed directly at an external location on the female's body. Here, we counted the number of spermatangia transferred to, removed from, and remaining on the female body during single copulation episodes. We measured behavioural and morphological characteristics of the male, such as duration of copulation and body size. Although males with larger body size and longer copulation time were capable of transferring larger amounts of sperm, females preferentially eliminated sperm from males with larger body size and shorter copulation time by spermatangia removal; thus, CFC could attenuate sperm precedence by larger males, whereas it reinforces sperm precedence by males with longer copulation time. Genetic paternity analysis revealed that fertilisation success for each male was correlated with remaining sperm volume which is adjusted by females after copulation.
 

DWhatley

Kraken
Staff member
Moderator
Joined
Sep 4, 2006
Messages
20,408
Reaction score
1,712
Location
Gainesville, GA
What a night! Last night's dive was pretty exciting by ending with an octopus piggyback ride
;) Octopus vulgaris (common octopus) has been known to use two mating positions. My previous mating videos have shown the distance position: male octopus at a distance extends his third right arm known as the hectocotylus (sex arm) into the opening in the female's mantle to place the sperm packet in the female's oviducal gland until eggs are fertilized. The second method of mating (shown in the video) is called mounting (looks like the octo is getting a piggyback ride haha). The male will leap upon the female and mount her mantle. Once he has mounted her, he will find the mantle opening with his sex arm. It usually only takes a few seconds for the sex arm to find the oviduct suggesting that there may be chemical cues involved.

I followed this mating pair for ~45min last night. Here are the highlights!

 

DWhatley

Kraken
Staff member
Moderator
Joined
Sep 4, 2006
Messages
20,408
Reaction score
1,712
Location
Gainesville, GA
Chemical cues correlate with agonistic behaviour and female mate choice in the southern blue-ringed octopus, Hapalochlaena maculosa (Hoyle, 1883) (Cephalopoda: Octopodidae)
Peter Morse, Kyall R. Zenger, Mark I. McCormick, Mark G. Meekan, Christine L. Huffard 2016 (Oxford Journals subscription)

Abstract
Chemoreception cues potentially influence intraspecific interactions of cephalopods, including mate choice. However, at present there is limited empirical evidence demonstrating whether cephalopods can use olfaction to identify the sex or identity of conspecifics. This study examined the responses of the southern blue-ringed octopus, Hapalochlaena maculosa(Hoyle, 1883), to conspecific odours during controlled laboratory trials. The ventilation rates in aquaria of 25 wild-sourced animals were measured during four treatments: baseline, sea water, sea water containing male conspecific odour and sea water containing female conspecific odour. When used as ‘receivers’ in trials, female H. maculosa significantly increased their ventilation rates in response to male odours, but not to female odours. However, female response decreased significantly with the receiver's size during female-odour treatments. The ventilation rates of male H. maculosa were statistically similar in all treatments. However, their ventilation rates showed a significant progressive increase over the observation period during male and female-odour treatments. Eighteen of these animals (nine females and nine males) were used in focal-animal trials 1 week after odour-cue experiments. Of these individuals, females were significantly more receptive to copulation attempts, and spent significantly more time per day in copulation, with males whose odours had elicited a weaker ventilation response in prior trials. These results suggest that female H. maculosa can use chemosensory cues to discriminate the sex, and possibly identity, of conspecifics and that this information might influence their mate choice. However, the mechanisms underlying these responses and subsequent copulatory access to females by males remain unknown.

  • © The Author 2016. Published by Oxf
 

DWhatley

Kraken
Staff member
Moderator
Joined
Sep 4, 2006
Messages
20,408
Reaction score
1,712
Location
Gainesville, GA
Egg Masses of Flying Squids (Cephalopoda: Ommastrephidae)

Dharmamony Vijai 2016 (subscription BioOne)
ABSTRACT
Ommastrephid squids have a pelagic lifestyle, with reproductive behavior that is characterized by the extrusion of fragile, neutrally buoyant egg masses, the release of paralarvae into the surface plankton, and the use of large-scale current patterns for larval transport, leading to the assisted migration of populations. Although the exact process of egg mass formation is unknown, the most accepted hypothesis suggests that, at spawning, eggs are first coated with oviducal gland secretion and released with nidamental gland secretions. Subsequently, the eggs mix with broken spermatophores or spermatangia for fertilization. The fertilized eggs are then extruded into the seawater to form a globular mass. These neutrally buoyant gelatinous egg masses are thought to maintain their location in the water column by floating at the interface between water layers of slightly different densities (above the pycnocline). The embryos develop within a favorable temperature range. Once hatched, the paralarvae leave the egg mass and swim to the surface. This review assimilates and assesses all available literature on the egg masses of ommastrephid squids. The data presented here clearly show how fragmentary our knowledge is about this important reproductive stage. Thus, increased efforts are required to develop observation and sampling techniques in the wild to obtain more direct evidence about reproduction in squids.
 

DWhatley

Kraken
Staff member
Moderator
Joined
Sep 4, 2006
Messages
20,408
Reaction score
1,712
Location
Gainesville, GA
Squid egg strategies

Published on Jun 25, 2014
Reproduction is one of the many challenges faced by deep-sea animals. In recent years, submersibles have allowed scientists to explore the lives of deep-sea animals in ways that were not possible before. One of the many exciting discoveries was that a mother of the deep-sea squid species Gonatus onyx broods her eggs by holding them in her arms, a behavior that had never been previously reported for squids. This shocking discovery was the first time scientists had evidence of parental care in squids. In 2012, a team of researchers led by Stephanie Bush, reported finding another species of deep-sea squid that broods eggs, Bathyteuthis berryi, suggesting that this form of parental care may be a common solution to a reproductive problem for deep-sea squids.

Publication:
Bush, S. L., Hoving, H. J. T., Huffard, C. L., Robison, B. R., & L. D. Zeidberg. 2012. Brooding and sperm storage by the deep-sea squid Bathyteuthis berryi (Cephalopoda: Decapodiformes). Journal of the Marine Biological Association of the United Kingdom. 92(7):1629-1636.

Video producer: Susan vonThun
Music: "Aqua lounge", www.freestockmusic.com
Script and narration: Stephanie Bush
Production support: Lonny Lundsten, Kyra Schlining, Nancy Jacobsen Stout, Linda Kuhnz, Bruce Robison
 

DWhatley

Kraken
Staff member
Moderator
Joined
Sep 4, 2006
Messages
20,408
Reaction score
1,712
Location
Gainesville, GA
Single and multiple mating reduces longevity of female dumpling squid (Euprymna tasmanica)
Amanda M. Franklin, Devi Stuart-Fox 2017 (subscription Wiley)
Abstract
For many species, mating is a necessary yet costly activity. The costs involved can have an important influence on the evolution of life histories and senescence. Females of many species mate multiply and this behaviour can inflict a longevity cost. Most studies investigating the effects of multiple mating on female survival have been conducted on insects and the effects in other taxa are largely unknown. We investigate the effects of both a single mating and a second mating on longevity in female dumpling squid (Euprymna tasmanica), a species in which both sexes mate multiply. Through comparing the longevity of virgin, once-mated and twice-mated females, we found that a single mating reduced female lifespan by 15 days on average. A second mating resulted in an additional 8 day (on average) longevity cost, despite no difference in total clutch mass, number of clutches, single egg mass or number of eggs per clutch between once-mated and twice-mated females. This demonstrates a cost to multiple mating which may be independent of the cost of egg production. Furthermore, total clutch mass and female lifespan were positively correlated, whilst female lifespan decreased with increasing average water temperature. The presence of an additive effect of reproduction on longevity suggests that multiple mating in cephalopods may have benefits that outweigh these costs, or that there is a conflict in optimal mating frequency between males and females.
 

Members online

No members online now.

Forum statistics

Threads
19,554
Messages
202,846
Members
8,403
Latest member
JPrater

Monty Awards

TONMOCON IV (2011): Terri
TONMOCON V (2013): Jean
TONMOCON VI (2015): Taollan
TONMOCON VII (2018): ekocak

About the Monty Awards
Top