Posts Tagged ‘Vancouver Island’

19 January, 2013 — Spermcasting

Saturday, January 19th, 2013

Hi Folks,

The news of some days, of course, is better than on others. And the news of the January 16, 2013, was grand! It contained a term I had never seen, but one I will be sure to use whenever possible, “spermcasting”.  I have to admit, when I first read it, it conjured up visions of fly casting, but with some essential differences; such as the type of rod one uses…  Aaah…  But, let’s not go any further down that road. 🙂

As the authors of the term meant it, in its basic form spermcasting would be seen in broadcast spawning animals such as many sessile marine invertebrates, and it would presumably have a feminine complement of ovacasting. In other words, “spermcasting” is the release of male gametes into the surrounding water as a means of reproduction. This type of reproduction is also seen in mobile animals such as echinoderms.  Broadcast spawning animals typically have simple reproductive systems, without any externally visible modifications.  The gametes are made and simply released through a “gonopore” into “the great outside world”.

A male sunflower star Pycnopodia helianthoides photographed "spermcasting" otherwise known as "broadcast spawning" in Northern Puget Sound.

A male sunflower star Pycnopodia helianthoides photographed “spermcasting” otherwise known as “broadcast spawning” in Northern Puget Sound.

 

A close up of the animal in the previous image showing the sperm suspension being released from the gonopores.

A close up of the animal in the previous image showing the sperm suspension being released from the gonopores.

However, spermcasting is something that is not generally considered to be part of the reproductive behavior of animals with a penis. In fact, over the array of invertebrate animals, the variety of penises, receptacles, openings, and the behaviors to get them all together is truly amazing, but spermcasting has not been considered a part of that behavior.  And why should it?   Because a penis is used to place sperm in some sort of receptacle or opening in a female, spermcasting has been thought to be unnecessary.   

While obviously commonly occurring, the actual physical act of the male’s transferring sperm to the inside of a female’s genital tract, “copulation”, is actually seldom observed in marine animals.  The reason for this is obvious.  For many species where reproduction involves internal fertilization or union of their gametes, reproduction may be an intrinsically hazardous process; and its duration and frequency is often minimized.  Often, copulation involves the intimate meeting of two animals that may be predatory and dangerous to one another. The terrestrial examples of the preying mantis or spiders such as the Black Widow come to mind, but the marine environment also has its share of dangerous liaisons. In such animals copulation often requires all sorts of behavior to ensure that the predatory behavior of both parties is “defused”. Some of the best known examples of such behavior occur in octopuses.

A large individual of the Giant Pacific Octopus, Enteroctopus dofleini. Highly predatory and cannibalistic, and reaching weights well in excess of 50 kg (110 pounds), precopulatory behavior that may last several hours is necessary before the animals can safely remain in each other's proximity for reproduction.

A large individual of the Giant Pacific Octopus, Enteroctopus dofleini. Highly predatory and cannibalistic, and reaching weights well in excess of 50 kg (110 pounds), precopulatory behavior that may last several hours is necessary before the animals can safely remain in each other’s proximity for reproduction.

 Copulation may place the animals at risk of predation by animals other than a potential mate. When animals are copulating, their attention cannot be on predator avoidance.  Consequently, natural selection has forced the development of behavior that reduces the risk of being seen – and eaten – such as nocturnal or reclusive mating. In some other animals, the act is over so fast, that the odds of an observer even noticing it range between slim and none. Pairs of one nudibranch species, Hermissenda crassicornis, can “do the deed” in a few seconds. And in those animals the act is reciprocal, the partners are hermaphrodites so each one gives and receives.  However, the process is seldom seen, or if it is, it is seldom recognized for what it is.

Hermissenda crassicornis, the so-called "opalescent nudibranch". Individuals of this hermaphroditic species reciprocally exchange sperm in some of the fastest copulations known.

Hermissenda crassicornis, the so-called “opalescent nudibranch”. Individuals of this hermaphroditic species reciprocally exchange sperm in some of the fastest copulations known.

As a result, generally, people have inferred internal fertilization or copulation by the presence of a penis and the associated female plumbing. And some animals are legendary in their endowment. Some of the best known in this regard are barnacles whose penises are often able to extend several times the length of the animal. Barnacles don’t actually copulate, relatively few crustaceans do, but they use the penis to deposit sperm in the females’ mantle cavities, and sperm behavior or the female partner ensures the gametes find their ultimate destination. However as the saying goes, this “pseudo-copulation” is “good enough for government work”.  Barnacles are sessile, glued to the substrate by glands in their head, consequently, their reproductive success, and their “evolutionary fitness”, depends on how far they can reach out to touch someone with their legendary penises. Fortunately, as they are hermaphroditic, any neighbor will do.

Balanus nubilus, the giant "cloud" barnacle of the N. E. Pacific. Large individuals reach up to about 15 cm (6 inches) wide at the base, and are often solitary or a relatively great distance from their neighbors. Spermcasting would definitely benefit their reproduction.

Balanus nubilus, the giant “cloud” barnacle of the N. E. Pacific. Large individuals reach up to about 15 cm (6 inches) wide at the base, and are often solitary or a relatively great distance from their neighbors. Spermcasting would definitely benefit their reproduction.

The need for (pseudo-) copulation, inferred by the presence of a penis, in barnacles could present a significant limitation in their reproductive capability relative to broadcast spawning animals, and hence it could severely limit their evolutionary fitness. Nonetheless, as far as anybody knew, barnacles put their amazingly large “equipment” to good use, copulated, and “THAT” was “THAT”.

Except, as it turns out “THAT,” is not “THAT”.  In a paper published online on January 16, some scientists have shown, rather elegantly that at least one species of barnacles; the common gooseneck barnacle of the NE Pacific, Pollicipes polymerus, does things quite a bit differently. They spermcast…

They are apparently able to both throw caution to the winds – or their spermies to the seas – and, amazingly enough, have this result in successful fertilization. Using genetic markers and some elegant and careful work, the researchers, from Dr. A. Richard Palmer’s lab at the University of Alberta, have shown that spermcasting occurs commonly in the goose neck barnacle, and even occurs in animals that can reach a partner to mate in the “traditional” manner.

Such extraordinary findings really upset the traditional view of spawning and copulation. After all, if barnacles can spermcast… it certainly seems that other animals possessing normal copulatory organs may also be able to do this.  No longer is it possible to look at the anatomy of species wherein the males possess a penis, and blithely assume that they only reproduce by copulation. 

Of such uncertainty, good research is made, as people have to ascertain the mode of reproduction.

As the authors of this paper state in the abstract, “These observations (i) overturn over a century of beliefs about what barnacles can (or cannot) do in terms of sperm transfer, (ii) raise doubts about prior claims of self-fertilization in barnacles, (iii) raise interesting questions about the capacity for sperm capture in other species (particularly those with short penises), and (iv) show, we believe for the first time, that spermcast mating can occur in an aquatic arthropod.”

More later,

Cheers, Ron
 

Tags:, , , , , , , , , , , ,
Posted in Off The Wall | Comments Closed

Predators In The Sand, Or…

Monday, September 5th, 2011

Thoughts On The Evolution And Natural History Of Scaphopods.

Why Here And Why Now?

This post is, obvously, the continuation of a series dealing with scaphopods and some  of the data I will be posting subsequently are also to be found on one or another of my website’s scaphopod pages.   However, these blog entries are not strictly duplicative; I have added a number of new data and I have  altered some of  the information to reflect my present thoughts.   Some of the ideas and data to be  presented here are somewhat iconoclastic, and contrary to what some authorities have proposed.  It is unlikely I will get the opportunity to publish these ideas in more formal, peer-reviewed, jounals, and as a result I thought this is an appropriate place to let the ideas see some glimmer of the light of day, albeit dimly and through some wet mud.  To the questions of “Why Here and Why Now?”  I think the reasonable answers are, “Because I think  this is an appropriate place and it is time.”  Or phrased another way, “Why Not?”

 One of Three Groups…

The scaphopods are the last of the classical molluscan classes to show up in the fossil record, with arguably the first unequivocal scaphopod being Rhytiodentalium kentuckyesnis Pojeta & Runnegar, 1979.  However, this unequivocality is not likely the case; the specimens of Rhytiodentalium are all significantly altered fossils, and from personal examination, it is impossible to tell exactly what they are.  Although some of them match the general shape of modern – and presumably – highly derived scaphopod shells, these “shells” appear to be comprised of small pelletized material.  It is unclear if these pellets are the result of significant or minor diagenesis.  In the first case, the shells could considered as scaphopods.  In the second, they would have to be something else, perhaps, some sort of worm tube.  I think the latter is much more likely than the former.

The term “armchair quarterback” has been coined to describe those individuals who after watching a football game at home on the “aptly-named” boob tube, dissect a quarterback’s performance and describe, a posteriori, what he should have done.   Of course, such a critique, if that’s what it may be called, is done without the experience of being under the tremendous pressure of the momnet on the field of play, without the sport’s equivalent of the “fog of war” clouding information input and, most importantly, it is done with the precision vision of hindsight.  Of course, in the armchair experience, errors made on the field become glaringly obvious.   One of the prime theories of scaphopod evolution is that scaphopods arose from an ancestor that either was in the extinct class, Rostrochonchia, or pehaps in its ancestral group, is the malacological equivalent of such airchair quarterbacking, however, with one glaring exception.  It is undoubtedly wrong, most likely as a result of being proposed by individuals who have had no experience examining or studying live scaphopods or, indeed, live animals of any sort..

There are a number of very serious problems with the Scaphopods from Rostroconchs derivation, not the least of which is that the scaphopod shell is univalved and tubular, while the rostroconch shell is bivalved of various non-cylindrical shapes.   Additioanally, the scaphopods are all predators or scavenger/predators; as a result, they must move; no predator on infauna waits for the prey to come to it.  Then, the scaphopod radula, the structure used to macerate, break, crush  or smash prey is the largest radula relative to the adult body size in all the mollusca.  On the scale of the organisms, it is a truly massive structure.   This massive radula is presumed to have been derived from an ancestor in the same group that is supposed to have given rise to the bivalves.  However, not only do the bivalves  lack the radua, but also any remnant of the head it is found in.  While the scaphopod head is reduced and kept within the shell, it is present, and has a relatively large brain, also a structure missing in the bivalves – and presumably their rostroconch ancestor.  The rostroconch shapes vary quite a bit, but one thing that is evident in all of them is that they are not streamlined and capable of easy movement through sediments.   Indeed, with the shapes typically found  in rostroconchs, it is quite likely, that like some oddly shaped infaunal bivalves today, they did not move at all as adults.  Scaphopods, on the other hand, are all mobile and many of them, given the appropriate stimulus, are capable of bursts of relatively rapid motion, after which they often stop, construct a feeding cavity and feed.  Given the sizes of the adult scaphopods, the  number of body lengths that they are able to move in any given amount of time, and the media that they move through, it is quite reasonable to consider many of them to be “high speed” predators.  Finally, recent molecular genetic work shows them to be grouped with the cephalopods, not the bivalves.

I think it is likely that one of the first branchings of the ancestral molluscan stock gave rise to a predatory organism that had a tendency to develop or elongate in a dorso-ventral direction.   In turn, this ancestor, over time, gave rise to three successful clades, eventually leading to the crown groups of the cephalopods, gastropods, and scaphopods.  All of these groups are all characterized by dorso-vental flexing in the visceral region, a well-developed radula, and elaborations of the cephalic tentacles.

Each of the three dorso-ventrally flexed groups shows particular adaptations and modifications for its primary habitat.  The cephalopods are highly successful predators in the pelagic enviroment.  Gastropods have radiated into virtually every possible niche except aerial flight, and are found in all terrestrial, fresh-water, and marine environments, although their ancestral habitat was the marine benthic epifaunal environment.  Scaphopods have become highly adapted for predation on organisms living in unconsolidated marine benthic sediments.

Cadulus tolmiei in situ, modified from Poon, 1987.

The above image shows Cadulus tolmiei feeding in sediment, cb= captacular bulb, dd= digestive diverticula, fc = foot cavity, g = gonad,  m= mantle,  pa = posterior aperture,  s = shell,

References:

Pojeta Jr., J. et. al. 1972. Rostroconchia:  A New Class of Bivalved Mollusks. Science. 177: 264-267.

Poon, Perry A. 1987. The diet and feeding behavior of Cadulus tolmiei Dall, 1897 (Scaphopoda: Siphonodentalioida). The Nautilus: 101: 88-92.

Steiner, G. and H. Dreyer.  2003.  Molecular phylogeny of Scaphopoda (Mollusca) inferred from 18S rDNA sequences: support for a Scaphopoda–Cephalopoda clade.  Zoologica Scripta. 32:343-356.

More to come…

Until then,

Cheers!!!

Tags:, , , , , , , , , , , , , , , , , , , , ,
Posted in Ecological Observations From Northeastern Pacific Subtidal Habitats | 5 Comments »

Scaphopods

Thursday, August 18th, 2011

Where

Recently I started scanning my images of scaphopods, an animal group from which very few people have seen living animals.  I did a lot of research on them actually starting about 1975, and becoming intensely active in 1983 and finally winding down about 1997.  I still have a paper or two to write but I haven’t done any field work in a long time.  I described two deep-sea species (1, 2) from specimens sent to me, but most of my work has been done on the scaphopods found in the shallow waters of the Northeastern Pacific.  Scaphopods are particularly common in many of the fjord environments north of the Strait of Juan de Fuca.  I spent some small amount of time examining their distribution in the waters of Northern Puget Sound, particularly in the northern American San Juan Islands.  In this area, two species of scaphopods, Rhabdus rectius and Pulsellum salishorum are found, and may be reasonably common in a few areas.   There a couple of marine research laboratories/field stations in that region, but as far as I know, I am the only person in the last half century who has worked at one of those labs and done any kind of research on scaphopods.

During the period from 1981 until 2003, I taught at various times at a Canadian marine station located in Bamfield, British Columbia, situated on a small inlet on the southeast side of Barkley Sound, a large fjord system on the west side of Vancouver Island.  This marine laboratory, known as the Bamfield Marine Station from its beginning in the 1970s until it morphed into the Bamfield Marine Sciences Centre in the early 2003, offers easy access to some of the scaphopod habitats of the Barkley Sound region.  For the two-year period from September of 1983 until September of 1985, I was the Assistant Director of the marine station, and actively carried out an intensive project on scaphopod ecology and natural history.  Subsequent to that time, I worked up data collected during that period, as well as initiating other scaphopod work, mostly with specimens sent to me by various researchers.   As a result, I have published about a half dozen research papers on scaphopods, and have a couple of more in the works… if I can only get my act together enough to finish them.

The Critters

Scaphopods, or “tusk” or “tooth” shells are mollusks that live as subsurface predators in the marine sandy or muddy sea bottom.  Covering an estimated 60% of the planetary surface, this is THE largest habitat in on the planet’s surface.  As the scaphopods are either abundant or dominant predators in this habitat, that makes them some of the most ecologically important animals. 

By last count there are about 8 to 10 people living today who have published papers on scaphopods, which may make them the most understudied of all important marine animals.  Given that a number of those people are museum workers whose entire conception of the Molluscan Class Scaphopoda is that it is a collection of oddly shaped shells, it is evident that the world-wide scientific interest in the group is probably so close to nil as to be statistically indistinguishable from it.

This means that to a very real extent, that anybody who works on scaphopods as a full, or even part-, time venture is on their way to committing, or has committed, scientific/academic suicide.  While it is true, to paraphrase one of my old profs, “If only five people work on your group, you can’t be ranked any lower than the fifth most prestigious worker on the group.” 

However, if only five people work on your group of interest, it means nobody will care what you write.  So, the good side is that everybody working on the group knows who you are. On the other hand, nobody else in the world – or known universe – cares who you are or anything about the animals…  If there is so little interest in group worldwide, no matter how good your publications are, they will simply disappear into the large black cesspool of unread papers as nobody will care about you write.  

Well, who am I to argue?  I will state, however, in my defense, after that statement that I am the senior author of the definitive reference about the animals published to date:  Shimek, R. L., and G. Steiner.  1997.  Scaphopoda.  In:  Harrison F., and A. J. Kohn, Eds. Mollusca II.  Microscopic Anatomy of the Invertebrates. Volume 6B: 719-781.  Wiley-Liss Inc. New York, NY.  ISBN 0-471-15441-5.   Whooopty-doooo…

 

Five species of Scaphopods found in the Barkley Sound region of Vancouver Island, British Columbia, Canada.  The scale bar is in millimeter.

From top to bottom, Pulsellum salishorum, upper two rows, females on the left, males on the right, next single row, Cadulus tolmiei, female left, male right, below that species is a single row of two Gadila aberrans, female left, males right, The next two individuals are Rhabdus rectius, female on the top, male on the bottom, and the lower-most individual is a single specimen of Antalis pretiosum (formerly Dentalium pretiosum), the “Indian Money Shell.”  These individuals were alive at the time, and in the high definition of the moment, the top four species have shells that are thin enough to be translucent, and the gonads from each gender are differently colored, so I could discrimate the sexes.  It is hard to see in the low res image here, but if you look at the top animals on the left, you can see a hint of pink in the shell, and that is the color of the ovaries of Pulsellum salishorum.

Heretofore…

Scaphopods were very economically important animals in the North American native cultures.  Given the common name of the “Indian Money Shell,” one species, at one time called “Dentalium pretiosum,” was collected and traded throughout large parts of Northern North America.  Here is an image from a National Geographic Magazine article about the trade; I was a technical advisor to the NGM for that article.  The scaphopods were harvested in by some of the tribes from the Pacific Northwest, both in what would become Canada and the U.S.  There are numerous “tales” about how the shells were collected, and at least two different and likely ways of collecting them.  Knowing what I found out about the habits of that species (now called Antalis pretiosum), it appears that very few of the actual living animals were collected, but rather shells containing small hermit crabs the primary source of “scaphopods.”  There is a hermit crab in the region were the scaphopods are found that is not coiled to fit into a snail shell as are most hermit crabs, rather this one, Orthopagurus mimumus, has a straight body and lives preferentially in the large “dentalium” shells.  The crabs crawl around on the surface of the habitat, while the living animals are generally deeply under the surface, at least a foot (30 cm) below the water/sediment interface.  In fact, the living scaphopods all have a rapid burrowing response – an exposed scaph is a dead scaph – as crabs and fish eat them.  In text books and references, they are often illustrated as having their pointed ends exposed from the sediments, and some are found this way,  between1 in 60, to 1 in about 10,000 depending on the species I have looked are exposed at any one time.   So much for the standard references…  More about why this should be so in my next issue of this blog.

Anyway, one of the more recent “proofs” of the hypothesis that it was mostly dead scaphopod shells inhabitated by hermit crabs that were collected actually comes from one of the National Geographic Magazine sites.  They have a series of images purported to be Antalis pretiosum, all of dead scaphopod shells taken by David Doubilet, and  all showing hermit crabs showing hermit crabs in the shells.  Doubilet was apparently in search of the wily dentalium and, by golly, he got some pictures of it… or at least of its shell.   Interestingly enough, there is an image also on their site showing Antalis pretiosum feeding below the sediment surface.  This wonderful image is a painting by Gregory A. Harlin, and it clearly shows that scaphopods don’t have legs…  Of course, Doubilet didn’t look at the painted image.   One further note that adds even more humor to this bit of fubardom (fubar = fucked up beyond all recognition) is that Harlin’s painting was done for the previously mentioned earlier article in NGM about the dentalium trade for which I was a technical advisor.  Harlin based his painting on my drawing of Rhabdus rectius feeding below the sediment surface that was used in Shimek and Steiner, 1997. 

A diagram of Rhabdus rectius shown in its feeding posture below the sediment surface, drawn in life from animals in aquaria. Compare with the painting by Gregory A. Harlin,

The dentalium shells collected on the coast were traded through out North America, at least as far east as the Great Lakes and were quite valuable.  They were used in the construction of jewelry and as ornamentation on clothing.  I have read, with no real estimate of the validity of the statement, that one or two of them could be exchanged for a tanned buffalo hide.  Consider that when you look at the image I have imbedded below.

 

Plains Indian neck ring jewelry in the collection of the Burke Museum,University of Washington, Seattle, Washington.

It has been reported, that given that the shells of the animals were quite valuable, it stands to reason that the one of the first things the Europeans did (in the guise of the Hudson’s Bay Company) was to “devalue the currency” by flooding the market with “counterfeit” shells.  When the HBC traders began to realize how valuable the shells were, they sent word back up the communications chain, and European shells were harvested in some relatively great numbers.  The European species, Dentalium entale, is/was essentially identical to Dentalium pretiosum and easily collected (and remember, both are now in the genus Antalis).  These were sent to HBC traders throughoutNorth America and used to purchase all sorts of trade goods.  So many shells became available that this sufficiently brought the value of the shells down so low as to make them worthless as trade goods for the coastal tribes as they could not harvest enough to get the traditional materials (such as buffalo robes, and they became dependent upon the HBC to sell them blankets).  If this is true, it is a great (?) lesson in market economics…

More on scaphs later….

Until then…

Cheers, Ron

 

Tags:, , , , , , , , , , , , , , , , , , , , , , ,
Posted in Ecological Observations From Northeastern Pacific Subtidal Habitats | Comments Closed

Gastropteron

Monday, August 8th, 2011

Although they look like they are nudibranchs, the two snail species featured in today’s posting are surely not nudibranchs, even if one is kind of sluggish in form and fashion.  The larger of the two, Gastropteron pacificum, is a bubble shell, meaning it has a shell that looks quite like a soap bubble and it is about as durable.  When sitting on the bottom, the animal is about the size of a grape.  The sides of the animal’s foot are expanded into two long lateral lobes that are normally folded up over the animal, but virtually nothing of the animal is normally visible as it is generally covered in a mucous sheet which, in turn, is covered by sediment particles.  The animal looks like a lump of mud on a bottom that is covered in lumps of mud, and so this is pretty good camouflage.  

Gastropteron pacificum, a stationary lump of pseudo-mud. The pink structure is a fleshy, tubular, siphon that brings in breathing water. 

Gastopteron pacificum individuals are found frequently in the spring in waters of the North American “Pacific Northwest” and if a diver ventures into its gorpy, mucky, muddy habitat – otherwise known when I was working in these areas, as a “Shimek study site” –  one can often see the trails left by these little guys as they move around, presumably in search of food or a mate. 

Gastropteron pacificum, leaving a trail in the mud as it crawls from there to here.

They are probably detritivores, as they are reported to eat detritus and diatoms in the laboratory, but I am not sure what they eat in nature, and neither, to the best of my knowledge, is anybody else.  I don’t think they have been studied in any detail which, if true, is quite a pity as they are neat little critters.  When something startles them – a diver (me) in my case for the photograph, or the presence of a bottom-feeding fish, such as the ratfish, Hydrolagus colliei, the little snail unfolds its foot flaps and flaps away.  They are quite strong swimmers and this appears to often be an effective escape response.  

Hydrolagus colliei

This “rat fish,” or “chimerid,” is a cartilaginous-skeletoned fish but obviously not a shark.  Individuals in this particular species can reach about 70 cm (28 inches) in length. Rat fishes are some of the most common predators in the soft-sediment ecosystems of the NE Pacific, and some of my unpublished data indicate they feed on mollusks, annelids, and echinoderms. 

A Gastropteron pacificum individual.

This little animal is swimming away from the most fearsome and horrific predator of all, a diver – in this case, of course, me.  I was sensed, probably by my water disturbances, and it then took off, and stayed waterborne for about 2 minutes.  Although Gastropteron swimming appears to be undirected, given the currents in the region, it will likely cover some distance before it quits swimming and falls back to the bottom.

If the Gastropteron is successful in its life, it find a good friend and they will do the snaily version of the “wild thing” resulting some time later in the deposition of some jelly-like “egg masses” attached to the bottom.  These are filled with small fertilized eggs (zygotes) that develop within the misnamed egg mass, which eventually dissolves releasing the larvae into the plankton. 

A group of Gastropteron “egg,” actually embryo, masses. I don’t know if all of these are deposited by one individual or if they aggregate during spawning to deposit the jelly-like masses (many snails in this region do form spawning aggregatations).

However, they don’t get a break!  There is a small sacoglossan slug, Olea hansinensis, in the area that searches out and eats the eggs of Gastropteron and its relatives.    

Olea hansinensis.

This is a small sacoglossan slug that eats eggs of cephalaspidean snails, such as Gastropteron.  This one was about 3 mm (1/8th inch) long, but larger individuals are said to reach about 13 mm, or half an inch in length.

More later,

Until then,

Cheers,

 

 

 

Tags:, , , , , , , , , , , , , , , , , , , , , ,
Posted in Ecological Observations From Northeastern Pacific Subtidal Habitats | Comments Closed

It Happened One Night

Saturday, April 3rd, 2010
    
It Happened One Night…2nd Edition.

This is the second version of this essay, the first one was destroyed when my blog had to be wiped as a result of being hacked, see the previous post for details.  I did not keep a record of the images that I had placed in the previous version, so if you read the previous version and had a favorite image, and it is not here, please contact me and I will see what I can do about inserting it. 

A couple of squid near the breeding assemblage

About 25 years ago I was teaching Marine Invertebrate Zoology at the Bamfield Marine Station (the name has been since changed to the Bamfield Marine Science Centre), a university-run marine teaching and research laboratory facility.  This facility is located on the shores of Bamfield Inlet, a small embayment on the south side of Barkley Sound near the southwest corner of Vancouver Island.  That particular year the course ran from late April until early June and was supposed to be a total immersion course – the students lived, breathed, ate, slept, and dreamed about invertebrates.  In this year, by late May, I was casting around for something of special interest for the students to work on, something above and beyond the “standard” course offerings.   

For about a week, we had been seeing a few squids swimming near the water’s surface next to the dock.  This was unusual, so I decided to go diving and see if I could see what they were up to.  These animals were Loligo opalescens, the “Pacific Market Squid” harvested in huge numbers near Monterey, California for calamari.  At the time, the southern populations were pretty well known, but not much was known about the northern populations. The local lore was that the squids, occasionally, would spawn in the inlet.  If spawning was to occur, I thought it would be nice to document this for a couple of reasons.  First – it would be ultimately cool to be in a squid spawning aggregation.  Second – I thought I might get some nice images that I could use in lectures.  Third – I thought I might be able to interest a few of the students in doing some actual research on some small aspect of the spawning.  All-in-all, if I could carry it off, it would be a win-win-win situation.  The only problem was trying to predict when the  animals would spawn, and then coming up with a scientifically valid short research project.   

Prior to this one particular morning, we had been seeing a few scattered squids near the surface in the inlet.  These surface-swimming animals were fully-grown, about 30 cm (1 foot) long, and bright white, so they were quite evident in the dark water of the inlet.  About 10 o’clock, after my lecture for the day was over, I wandered down to the dock, and noticed that the squids were present in larger than “normal” shoals, maybe up to 30 to 50 animals in each fast moving school, so I thought this would be worth a look.  I asked around and found a dive partner and dock tender, and we plopped ourselves in the water about 30 minutes after 10 AM.  To document our dive, I took along my underwater camera system, which consisted of an Olympus OM-2 in an Ikelite housing, with two strobes attached; one triggered by the camera and the other slaved to the first one.  The film was Kodachrome-64, my film of choice for underwater photography.  

Solitary Loligo opalescens

Dropping down to the bottom, at a depth of about 17m to 18 m (55-60 ft), we found a small mass of squids in a frenzy of activity.  As a result, I started my personal frenzy of activity taking some images.  It soon became evident that a couple of individuals were spawning, but that most of the animals were just “interested” observers, squid voyeurs, I guess.  I documented a solitary female spawning and depositing her egg capsules.  I presumed copulation had already taken place, as I saw no obvious mating activity.  I had seen movies of some squid spawning aggregations, and it was obvious that what we were watching was not a normal spawning event.  However, I thought it might be a precursor to the “real” action.       

Solitary Female Loligo opalescens Spawning. Note The Extruded Egg Capsule Between Her Arms.

Solitary Female Ovipositing. Note Egg Capsule Between Her Arms.

Same Individual As In The Previous Figure. Note The Egg Capsule.

Egg Capsules Deposited By The Single Female Over The Course Of Her Spawning

Egg Capsules Produced By The Single Female Over The Course Of Her Spawning.,

For about a week the people of the village of Bamfield had been catching squid by jigging for them near the government-owned docks in town.  So, after seeing the events off of the laboratory dock, I thought that there might be a small mass spawning event occurring near the dock in the upcoming evening.  It would be a “small” event simply because the area was constrained.  The inlet was not wide and was relatively shallow, about 18 m (60 ft) deep at its maximum in that area.  I arranged for another dive buddy and boat tender and we went down to the town docks about 10:30 pm to do our dive.  As usual, I took my camera system along to document interesting “happenings.”   

When we arrived at the scene, the fishermen already there said that jigging was “slow.”  Squids were visible, but sparse, and not many had come into the area where the fishermen were.  To avoid upsetting the fishermen, we dove well away from them.  This also prevented us from being “jigged.”  Having a sharp squid jig tear open and flood one’s (very) expensive dry suit can really ruin the experience of the moment!   

When we first got into the water, few Loligo were around, but within a couple of minutes they started to aggregate around us, probably attracted by our diving lights, and the large pile of rocks on the bottom nearby.  At first there were just a few solitary individuals, then a few doublets, and then quartets, and then … large groups; Too large and too fast to count.  All of a sudden the action began.   

Although the spawning aggregation appeared terribly chaotic, with thousands – yes, thousands – of Loligo jetting around from all directions and bumping into each other and us, after a bit of observation, it became clear that what appeared to be an unruly affair was really quite well “choreographed.” 

From the outside in…   

The animals approached the spawning site alone or in small groups of up to about ten individuals.  As they approached they had normal coloration; brown to reddish brown tones predominated on the bodies and the arms’ outer surfaces.    

A Squid Pair Above The Main Spawning Site

A Quartet Of Squid Approaching The Spawning Site.

At the outermost region of the spawning site, about 5 to 6 m (15 to 20 feet) above it, the individuals were actively fighting with one another to find a mate.  Females were “attacked” by males that wished to mate with them, and often two or more males fought each other for each female.  This was a brutal, winner-take-all, competition!  Skin was ripped off and the combatants used their beaks to rip pieces of flesh from their opponents.  The females were NOT passive participants in this rough foreplay; they were actively fighting as well.  Presumably, the strongest, most fit male prevailed.  During this activity, both males and females were white.  They did not flash or change colors.   

Mating/Foreplay Damage Making the mate choice - maybe... Lots of action here.

Foreplay - but getting near the final choice of mates. Note the bite damage on the male (lower animal).

Precopulation - "Foreplay" - Two Males and One Female

Loligo opalescens foreplay or copulation well above the egg deposition site

 As the combat continued, the participants got closer and closer to the bottom, and eventually one male prevailed.  He got into the oviposition position; holding the female from behind and below, with his eight arms wrapped around her.  Copulation, the transfer of a spermatophore (sperm packet) from the male to the female, occurred once this posture was stabilized.  The animals were now about 3 m (10 feet) above the bottom.  Once he was securely holding his mate, the male’s color pattern changed from pure white all over, to having a white body and reddish-brown tentacles.  The female remained totally white.  Once this color pattern was established all other males avoided the pair, and ceased jostling the resident male for possession of his female.  I suspect the color pattern change was THE signal that mating had occurred and that this particular female was no longer available.   

Mated Pairs Depositing Egg Capsules.

After the male’s color changed, he did all of the subsequent swimming for the pair.  He moved the female to the oviposition site and began to push her into the mass of egg capsules that were already at the site.  As they approached the site, the female extruded and formed an egg capsule which was held in her arms.  Once the male pushed her into the egg capsule mass, or onto any other acceptable area, the female wrapped the distal, adhesive and ropelike, end of the egg capsule around anything, such as other egg capsules, a sunken twig, a rock, a diver’s mask strap, which would hold it in place.   

The egg deposition frenzy, overall there were hundreds of pairs of squid at this one small site.

Egg Capsule Deposition

Frenzied action a couple of meters above the main egg capsule mass

Spawning pairs and the main egg capsule mass.

  When first formed, these egg capsules were about the size of one’s little finger, but they became larger as they absorb water.  From subsequent studies, part of the project we later did, I found that each egg capsule in this region contained about 150 eggs, sequestered within a series of protective – and toxic – membranous coverings.  I was unable to count the number of egg capsules produced by any specific single female, the situation was just too chaotic for that.  In the California areas other studies found that each female produced about 20 capsules.  If the same number was produced by these northern Loligo, each female would deposit about 3000 eggs in her one night stand.  

Newly deposited egg capsules

Egg Masses The Day After Spawning. The Masses Are About A Meter Thick.

After the final capsule was deposited, the male released the female and they both slowly departed the area.  The males seemed to be a bit more active and I surmised that at least some of them might try to mate again, as each one produces numerous spermatophores, and they only use one per female.  However, the action was so frenzied that I was unable to follow any given squid more than a few seconds, so it is possible that one shot was all the males had.  The females appeared to be totally spent; they swam erratically and weakly.  They often travelled only a short distance prior to settling to the bottom and dying.  The males probably swam a few more hours, at best, but they, too, don’t survive long.  Individuals of both genders are badly injured by the experience.   

New Egg Capsules, The Day After Deposition, My Dive Partner For Scale.

During the flurry of spawning activity predators made their appearance.  In the area where I was diving these predators were seals and California sea lions which would come blasting through the spawning masses biting up squid as they went.  Fortunately, they decided big ugly divers in rubber suits didn’t match their search image of calamari.  In other areas, larger sharks, such as blue sharks, will also come into the spawning squid schools, but, blissfully, I didn’t see any of those in the aggregations I dove in. 

After the spawning was over, the bottom was littered with egg capsule masses and dead or dying squid.  Over the week following the spawning, some of my associates and students and I did some diving to make measurements of the squid egg masses.  Scattered all over the bottom, from just below lowest low water to beyond diver depth, were small individual egg capsule aggregations.  Each of these covered about 0.3 square meters, (about 3 square feet) and there were about 1.3 of them per square meter (10 square feet).  I collected some of these aggregations, and found that each contained, on the average, about 1,940 capsules.  Each capsule contained about 150 eggs, meaning each capsule mass was the result of 194 squid pairs, and contained 291,000 eggs.   

Dead squid the morning after the spawning event.

Mass of dead squid, the morning after.

 We did diving surveys to determine the extent of the night’s spawning activity.  This particular night’s spawning aggregation extended along about 11 km (7 miles) of the southern edge of Barkley sound.  The largest egg mass we found in a quantitative survey area was 69 square meters or 742 square feet, however, we saw some much larger egg masses.  Unfortunately, these were seen during the spot surveys for determining the whole area covered by the spawning aggregation, and we could not return to them.  We estimated the largest measured spawning aggregation was result of 24,000 spawning pairs of Loligo, and based our quantitative measurements of small egg mass abundance we estimated that during that one night of spawning, in the Bamfield area, over 64,000,000 squids spawned!   

Urticina corieaca, a sand dwelling anemone, and squid corpses. It normally would eat squid, but was sated the next morning.

 Loligo opalescens eggs take about six weeks to hatch in that region, and some of the egg masses were followed for that length of time.  After hatching, the remnants of the membranous egg coverings were still noticeable on the bottom for another several weeks in places.  As long as the egg capsule membranes were intact, nothing was seen eating the eggs.  Stupidly, I did not wear gloves during my initial examination of the egg capsules and the eggs when I was tearing and cutting open the egg capsule membranes.  After a few minutes of handling the membranes my fingers lost feeling, and a few minutes after that my hands became numb and immobile.  The area of numbness continued to expand until finally my arms became numb up to the elbows.  It took about 2 to 3 hours before the feeling slowly returned to my arms and hands.  Obviously, whatever is in the membranes would be effective at deterring predation.  In over 100 diver hours of examining the capsule masses, no animals were seen eating the eggs, although we saw many animals positioned on or in the masses.  If egg capsules were torn or cut open underwater, red rock crab individuals, Cancer productus, rapidly approached and started eating the eggs or developing embryos, further illustrating the protective function of the capsular membranes.  The long decay period for the membranes after the squids had hatched also indicated that the membranes contained either or both antifungal and antibacterial agents.   

A sunflower star, Pycnopodia helianthoides, on an egg capsule mass. The star was not eating them.

Old egg capsules, near hatching. They absorb water and are about three times the size they were when deposited.

During the several weeks it takes them to hatch, other animals in the area seem to consider the toxic egg capsules as "just part of the habitat."

 Reference:   

Shimek, R. L., D. Fyfe, L. Ramsey, A. Bergey, J. Elliott, and S. Guy.  1984.  A note on the spawning of the north Pacific market squid Loligo opalescens(Berry, 1911) in Barkley Sound, Vancouver Island, Canada.  Fishery Bulletin.  82:445-446.   

Tags:, , , , , , , , , , ,
Posted in Ecological Observations From Northeastern Pacific Subtidal Habitats | 2 Comments »