To land-dwelling humans, deep sea hydrothermal vents would seem like a vision of hell, amidst the crushing darkness you have plumes of superheated water, mixed with noxious sulfides, erupting from fissures on the seafloor. But for many deep sea animals, this “hell” is in fact a vibrant oasis in the middle of the abyss. This lively habitat is made possible thanks to bacteria that are able to extract energy from the sulphurous waters billowing from those vents. In the absence of sunlight, these chemoautotrophs form the foundation of the food chain. Some tube worms have been able to co-opt the power of these bacteria by housing the microbes in their gills, enabling them to grow to enormous sizes. Their tubes form dense, forest-like habitats for many other animals including other polychaete worms, fishes, crustaceans, and molluscs. This sets the stage for all kinds of complex ecological interactions, and that includes parasitism.

https://dailyparasite.blogspot.com/2024/02/ascarophis-globuligera.html

The post Parasitism at Hydrothermal Vents first appeared on Deep Sea News.

I was just listening to a podcast about how sea sponges use the pores all over their body to “bring in food and release wastes” and I’m pretty sure that’s a scientific way of saying the holes in sponges are all just mouths and buttholes so does that mean that when I’m using a sponge in the shower I’m cleaning my body with mouths and buttholes? Someone get me a marine biologist. And a loofah. And maybe some bleach.  -The Bloggess

All around you are animals with a single hole serving as both a mouth and anus.  These mono-orifice animals have an incomplete digestive system.  In contrast, those animals blessed with two holes, a tubular digestive system with an in and out hole, possess a complete digestive system.

Sponges are a bit of a unique case as a loose conglomeration of cells in a body full of pores and channels.  None of this really resembles organs or a digestive system with digesting occurring within individual cells.  However, the Cnidarians, including jellyfish, anemones, and corals,  are all uni-aperture.  We can also add the Ctenophores, the comb jellies, into this lone door group of animals.

In the flatworms, the Platyhelminthes, its mixed bag of one, two, and even more bodily gateways.  Most flatworms have no anus, but some particularly long species do possess an anus. In rare cases, flatworms with very complex branch guts can have more than one anus.  By the way, the plural can be either anuses or ani.

Peeping at the underside of a starfish, you might have only noticed a giant mouth.  You may be thinking to yourself, “I’ve never seen another opening.  Do starfishes have an anus?”  Of course, this is one of the great questions of life.  Indeed,  most starfishes have a complete digestive system with the anus being a small opening on the top. However, there is a large order of starfish, the Paxillosida, that lack an anus.  The only other group of Echinoderms to lack an anus, and even an intestine, is the brittle stars.

A solitary black hole may also occur during specific phases of animals life cycle.  An incomplete digestive system is known in some insects including the sap-sucking aphid relatives, the Phylloxera, during their sexual phase.  Some larvae including those of some fish and proboscis worms can be anally deficient.  Certain lifestyles also can lead to solo agujero such as in parasitic species, like parasitic copepods.

It’s important to remember that all animals start development with one hole, the blastopore.  In the ventrally chosen, a second hole forms later.  So the question remains if some animals form only a single hole is it a mouth that used as anus or anus used as a mouth?  The proverbial digestive pore chicken and egg scenario.

As described in this excellent post, 

Blastopore formation is started by a protein called disheveled, which gets stuck at the top of the egg and then activates a specific set of genes. In the same location of jellyfish embryos, however, there are genes strikingly similar to the mouth genes of bilaterians. In the sea urchin, a bilaterian, these same mouth genes are also on the top of the embryo. However, disheveled has moved to the bottom. The blastopore forms at this new site of disheveled accumulation, rather than at the mouth. The mouth genes that remain on top still direct the formation of the mouth there. Martindale and Hejnol posit that moving disheveled from the top to the bottom of the embryo in some animals moved the location of blastopore, but that the mouth stayed put. In some bilaterians, like urchins and humans, the blastopore then became the anus. In this scenario all mouths are homologous to each other, whether the animal has one or two holes.

Evolution can be a truly wonderful thing and then sometimes it can produce an animal with a mouth that still uses its anus to feed.

The post A Tale of One Opening first appeared on Deep Sea News.

Sub-Neritic Gentrification

For November we will be doing some deep thinking about deep-sea mollusks in an attempt to understand the complex history and adaptations of these animals living in the depths of our oceans. Biodiversity of today’s marine snails can be traced to several different ecological and environmental phenomena, but in the Deep-Water Helmet Shell Galeodea keyteri, it is likely a case of adaptive radiation exploring new realms. The Helmet Shells (Cassidae) are a speciose group of large, shallow-water tropical and temperate marine snails that range among the intertidal coral rubble and sand flats to offshore muds, but as this evolutionarily successful group of gastropods continued to diversity into different niches, several species moved into deep-water to establish new ways of living. At these depths staying alive presents serious challenges with an extremely cold, low oxygen, nutrient-poor, and high-pressure environment, so some deep-water species trended to smaller, slow-growing physiologies like as a way to successfully conserve energy and resources. Since the dark depths lack sunlight needed for algae to grow, most species of deep-sea mollusks are either scavengers or predators, with little resources for vegetarians to survive. Like all Helmet Shells, Galeodea keyteri is a carnivore, specializing on starfish, brittle stars, and urchins. Catching their slow-moving prey with a muscular foot, glands in the proboscis secrete a fluid rich in acids that dissolve the echinoderm’s calcium-carbonate skeletons, while a radula drills into the weakened parts of the body to extract nutrients from their internal organs. A tough environment requires innovative strategies and hardy adaptations for a species to survive. Ain’t natural selection grand?

Molluscan Methuselah

While some species of deepwater mollusks are derived from shallow-water taxa that extended into and adapted within deep ocean ecosystems, other taxa of marine mollusks are taxonomic geezers with a much longer history. The Slit Snails (Pleuorotomariidae) are perhaps the oldest still-living lineage of marine snails, extending back in the fossil record more than 500 million years. Named because of its long slit at the aperture allowing for extension of their respiratory siphon, they were abundant in the shallow reefs throughout the world. Between the Late Cretaceous (ca. 90 million years ago) and the middle Eocene (ca. 40 million years ago) is when most modern lineages of shallow-water reef-living gastropods originated and diversified, and also the time when slit shells seem to disappear from that same fossil record. Among paleontologists and malacologists, the general hypothesis is that these modern taxa somehow out-competed the slit shells for food, or perhaps were more adapted to changing marine climates or fluctuating sea levels of the time, forcing the slit shells into progressively deeper and deeper water. This type of ecological displacement and bathymetric submergence has been seen in many other deep-sea groups, including corals, crinoids, brachiopods, and fishes. Today, slit shells are found in depths exceeding 3,000 meters, living the hi-life eating sponges in a cold, dark, lonely, nutrient-poor world.

Die-Hardest

As far as the origins of deep-sea gastropods go, we’ve visited two scenarios: new lineages of shallow-water snails radiating into deeper waters, and those formerly shallow-water taxa that have been out-competed in the shallows and forced into deeper, less productive habitats. But there’s a third group of deep-water snails that are so tough, so extreme that they can live in shallow and deep water. Here is the Checkered Hairsnail (Trichotropis cancellaria; Capulidae), the James Bond, the Bruce Willis, and the Rock all coiled up into one extreme snail that ranges from the intertidal zone to depths of nearly 2,000 ft. (600m). Is it true grit or it’s hard-boiled soul that make it impervious to the relentless cold, pressure, and darkness of the deep sea? Their broad range is more likely the result of two things: (1) a wide and variable physiology that can tolerate the extremes of shallow to deep; and (2) its broad diet that it can obtain at any depth. You see, the Checkered Hairsnail is a suspension-feeder, meaning it feeds on the decomposing bits of animal debris suspended in the water, which it traps by sticky mucous, and that kind of detritus is found in all habitats. However, it’s a sneaky critter. When the floating slurry of decomposition becomes scarce, they will parasitize tube worms by inserting their proboscis down the mouth of the worm and pumping out the contents of the worm’s stomach. Evolution: the weirder the better.

Slo-Mo Snail
Shallow-water gastropods live the good life. Warm water, a sunny sea rich in oxygen, and plenty of food provides them the metabolism to live fast, grow big, and die young, relatively speaking, of course. The flipside in the deep sea is a life of constant near-freezing cold, little available food, and water suffocatingly sparse in oxygen. This shell of the Catalina Turrid (Antiplanes catalinae, Pseudomelatomidae) who lives at depths of up to 4800 ft (1460 m), tells its story of life in this harsh realm. Growth lines, which indicate the increase and cessation of shell development, are seen as wide bands often far apart in curving spire of fast-growing shallow-water shells. In this species, the growth lines are close and compact, showing very slow growth and likely a long life. Their low metabolism provides little extra energy for their minimal growth and reproduction, so these snails probably take the developmental route of the tortoise over the hare. This shell tells another and more concerning story. Once only collected during deep-ocean trawls by research vessels, this species was prized by collectors as a rarity and an oddity. With commercial fisheries abandoning over-exploited fishing grounds along the shallower coasts, fishing has gone into the deep ocean to tap into those fragile resources. This specimen was taken as unintentional bycatch by a deep-water shrimp trawler, and though it wasn’t the target of the fisheries, the sparse populations of these slow-growing snails cannot sustain even the modest impact by commercial fisheries

Post-Docs Please Enquire

The curse of working with deep-sea gastropods is how few specimens are in museum collections, and what very little is known about them. That too is the siren’s call of opportunity in deep-sea malacological research. The Japanese Pagoda Shell (Columbarium pagoda, Turridae) has been known to science for close to 200 years, based on relatively few well-documented specimens in museums and private collections scattered throughout the world, yet virtually nothing is known about their ecology. Diet, trophic niche, age, growth rates, reproduction, population structure, predators, parasites, physiology, ecological associations, movements – none of that has been adequately documented. If all mysteries in the ocean were solved, there would be no jobs for future under-paid post-docs or over-worked assistant professors. Those with grant funding, a modicum of workaholism, and access to deep-sea technology could pioneer new directions into a richer ecological understanding of the deep ocean’s marine mollusks. That siren’s call can just as easily dash unfeasible projects on the rocks of financial destitution and lead to deep regret of one’s research program and entrée into a life of constant self-medication and personal validation. These mysteries await the bold, but favor the wise.

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

Stuff growing on dolphins though…especially when the things in question look like dangly bits of goo…

And what are these things exactly? Barnacles. Of course they’re barnacles…

They’re known as Xenobalanus globicipitis, aka “my nemesis in life”. Xenobalanus globicipitis are barnacle specialists, attaching only to fast-moving marine mammals, and even then mostly to the areas exposed to the highest flow (tails and dorsal fins are great spots for that). They’ve got gooey soft elongated bodies, and even to the people who like them enough to study them, they look “more like a leech than a barnacle” [2]. To hold on, X. globicipitis have a tiny cup anchor at their base, which digs into the dolphin’s skin:

Xenobalanus globicipitis “has broken with all balanid [barnacle] traditions” [3], because so few barnacles have long blob bodies and cup-shaped back-ends. It gives them that extra maddening look because you’d think they’d be so easy remove, if only dolphins could do it. In contrast to their long bodies, their top end is capped with a little tissue plate. Out of this plate the barnacle feeding structures emerge (pretty much the only thing on this animal resembling a barnacle at all):

So they just hang there, feeding in the current created by dolphins as they swim. Of course they can’t be like all the other self-respecting barnacles and live on rocks. Or even like the ones that pretend to be crab gonads. NooOOOOooo…they’ve evolved to sully the sight of dolphins far and wide, making my left eyelid twitch and my lip curl. Ruining all dolphin sightings from now until the end of time.

I can sympathize on one front though: it would be fun as heck to spend your whole life riding on the back of a dolphin. They may drive me crazy, but I can definitely give them that much.

*I realize they’re imbedded in the skin and it’d probably be smelly and gross. Don’t ruin it.

Work Cited

[1] Occurrence of the Barnacle, Xenobalanus globicipitis, on Coastal Bottlenose Dolphins (Tursiops truncatus) in New Jersey

http://www.jstor.org/stable/20107916

[2] Whale barnacles: exaptational access to a forbidden paradise

http://paleobiol.geoscienceworld.org/content/31/2_Suppl/27.full.pdf

[3] Xenobalanus globicipitis (Crustacea: Cirripedia) on dusky dolphins (Lagenorynchus obscurus) off Namibia: Hitch-hiker’s guide to the seas

https://www.imr.no/filarkiv/2004/01/Hitch-hikers_Guide_to_the_Seas.pdf/nb-no

The post That looks terrible on you Dolphin- take it off! first appeared on Deep Sea News.

I’d like you to meet one of the most beautiful animals I’ve ever seen:

The small creature I’d found was a Sapphirina copepod, or as I like to call it, a sea sapphire. Copepods are the rice of the sea, tiny shrimp-like animals at the base of the ocean food chain. And like rice, they are generally not known for their charisma. Sea sapphires are an exception. Though they are often small, a few millimeters, they are stunningly beautiful. Like their namesake gem, different species of sea sapphire shine in different hues, from bright gold to deep blue. Africa isn’t the only place they can be found. I’ve since seen them off the coasts of Rhode Island and California. When they’re abundant near the water’s surface the sea shimmers like diamonds falling from the sky.  Japanese fisherman of old had a name for this kind of water, “tama-mizu”, jeweled water.

The reason for their shimmering beauty is both complex and mysterious, relating to their unique social behavior and strange crystalline skin.

A key clue: this sparkle is only seen in males. Males live free in the water column, but females make their home in the crystal palaces of a strange, barrel-shaped jellies called salps. And though they’re not flashy, these parasitic princesses have huge eyes relative to males. Perhaps female sea sapphires look out upon an endless expanse of ocean sparkling with blue and gold, searching for the a particularly luminous shine. Or it could be that males use their shimmer to compete with one another, like jousting knights in shining armor, while the females watch on. About the social life of sea sapphires, we know very little. But how do they shine in the first place?

I was lucky to find one, but sometimes they are found in astonishing numbers. My friend and colleague Erik Thuesen once told me about his work on an ROV, as the submersible was coming to the surface, “it passed through this amazingly sparkling layer of iridescent Sapphrina”.  A rare sight to see; not, perhaps, due to the rarity of these ocean gems, but the rarity at which we enter their world. Even as you read this, wherever you are and whatever you’re doing, they’re out there right now. Quietly shining in their own private universe of stars.

 Work Cited and additional reading

[1] J. Chae, S. Nishida (1994). Integumental ultrastructure and color patterns in the iridescent copepods of the family Sapphirinidae (Copepoda: Poecilostomatoida). Marine Biology, Volume 119, Issue 2, pp 205-210 

Yuval Baar, Joseph Rosen, Nadav Shashar (2014). Circular Polarization of Transmitted Light by Sapphirinidae Copepods. PloS ONE. DOI: 10.1371/journal.pone.0086131

The post The most beautiful animal you've never seen first appeared on Deep Sea News.

Sacculina. You HAVE been assimilated:

Lampreys – because parasitism by invertebrates is for woossies.

For the ladies… Philometra (a nematode) will eat your ovaries from the inside out:

Pennelid copepods, because half a dozen toothbrush-sized copepods jammed in your bum just feels soooooooo good:

Tongue biting cymothoid isopods: because you didn’t need that tongue anyway; it’s not like fish can talk, AMIRIGHT??? :

Schistocephalus. I know, let’s play “How many giant tapeworm larvae can we jam in a 2 inch stickleback?”!:

Diplostomum inside your eyeball.  What are you complaining about?  Nature gave you TWO eyes, TWO.

Anilocra. “Hey Gary man, you got a little something on your face”:

Cyamid amphipods:  Turning whale skin into the Grand Canyon since … well, since evolution

Siphonostomatoid copepods on a flatfish.  “I think there’s something in my eye”

Lernaeenicus. “We’re doing the eye thing now right?”

Pomphorhynchus. What, you DON’T have giant yellow worms in your rectum?

The post TGIF (just) – Resistance is Futile, you WILL be assimilated first appeared on Deep Sea News.

So how about those oarfish huh?  Two washing up in the same week; it must be The End Times, because, you know, two is a trend and all that, CNN says so.  Actually, I am pretty sure that will prove to be nothing more than probability rearing its beautiful head.  If, like CNN,  confirmation bias makes that coincidence hard for you to swallow, then I highly recommend you read Leonard Mlodinow’s The Drunkards Walk; it’s a really interesting look at how probability and chance impinge on our daily lives.

One very lucky bunch of students had a once in a lifetime chance after the oarfish bodies washed up – the opportunity to help one of the world’s best known parasitologists, Armand Kuris of UCSB, to pull some worms out of a fish that has only been examined for parasites a couple of times ever.  I for one would have loved to join them.  So what did they find?

In short: some larval tapeworms and an acanthocephalan in the gut.  The baby tapeworms mature in sharks, so in this case the oarfish would be acting as intermediate host.  The acanthocephalan was an adult, and the oarfish likely got it from eating a prey item, probably a small fish or shrimp, in which the larval stage, or cystacanth, would have been hiding.

These findings are stunning in their supreme average-ness!  No radical weirdo worm never seen before, no giant elongated beastie  as befits the longest bony fish in existence, just a few run-of-the-mill fish parasites you can find in any old teleost.  The larval tapeworms, in particular, are among the most common parasites found in marine fishes.  At the intermediate stage they are not at all fussy and as such they show up in the guts of all sorts of fish.  Literally, ALL sorts of fish.  Acanthocephalans are a bit more interesting.  Those are a minor phylum known well to parasitologists but not really many other folks.  They are characterised by having a body cavity (like nematodes but unlike tapeworms), but no gut (like tapeworms but unlike nematodes).  their most distinctive characteristic is a wicked spiny proboscis that they use to attach to the gut wall.  Here’s a selection:

The biggest thing to take away from the oarfish necropsy is that they are, in essence, just like every other fish – full of parasites.  As I like to say, NO FISH IS AN ISLAND, they are all mobile habitat patches for all manner of little beasties.  The world’s 28,000 or so fish species may host 140,000 parasite species or more.  I explain how here, and there’s a handy graphic about which bugs live where.  In having these parasites, this very special fish proves that it’s not so special after all.  In a very real sense, it’s just another piece of meat.

The post Accidental Parasite Week continues: the Oarfish edition first appeared on Deep Sea News.

My good colleagues Janine Caira and Georga Benz wrote a paper way back in 1997 about one of the strangest parasites ever recorded in an animal.  This paper has stuck with me ever since, I think because I saw the original photos when I visited George’s lab back when he was with Tennessee Aquarium (he’s now at Middle Tennessee State U.).  So, I thought I’d revive it for you guys; the story goes like this:

Janine and her colleagues were unable to determine the path of entry, but they showed good evidence that the eels were alive in the heart prior to the shark being killed and put in the fridge, because their guts were full of blood and there were pathologic changes to the heart.  Their conclusion?  That this was a facultatively parasitic relationship.  In other words, the eels didn’t need to be living in the sharks heart (that would be obligate parasitism), rather they took advantage of an opportunity to get a meal.  They proposed that the eels probably attacked the shark after it had been hooked and was dangling, distressed, from the longline.  They had some evidence that the shark was probably resting on the bottom, which may have made it easier for the eels to find.  The pugnoses somehow gained entry (hypothesised to be through the gills) and made their way to the heart, where they dined on the beasts blood up until it died.  Maybe they would have burrowed out again after the animal expired, maybe they would have suffocated (remember – the eels had be swimming in and breathing the sharks blood once they were inside, how bizarre is that?).  We’ll never know because the carcass went in the fridge, which ended things for the eels, but also led to this amazing discovery.

The horrifying part is that the shark was almost certainly alive as the eels made their way into its flesh and began to consume its life blood from the inside.  It would have been a long, slow and nasty way to go out.  It just goes to show that even when you are at the top of the food chain, you’re never really at the top of the food chain…

Caira, J., Benz, G., Borucinska, J., & Kohler, N. (1997). Pugnose eels, Simenchelys parasiticus (Synaphobranchidae) from the heart of a shortfin mako, Isurus oxyrinchus(Lamnidae) Environmental Biology of Fishes, 49 (1), 139-144 DOI:10.1023/A:1007398609346

The post I’ll see your horrifying crab barnacle and raise you a heart eel first appeared on Deep Sea News.

Scientists currently know of 112 species who’s preferred habitat is the renal sac of a cephalopod.  Actually, each species prefers a different kind of cephalopod—Broadclub Cuttlefish, Argentine Shortfin Squid, Giant Pacific Octopus.  Conceivably, each cephalopod is chauffeuring its very own and unique urine-loving passengers.

The Dicyemids, or if you are really old school like me the Rhombozoans (literally Latin for spinning top animal), are esoteric animals with a simple body plan and horrifyingly complex reproduction.

Think of Rhombozoans as a parasitic Reese’s Cup that likes to hang out in your kidney.  The chocolaty outside is a layer of skin/feeding cells and the o’ so delicious peanut butter middle is a fun loving center of cells for reproduction.  Thus the biological blueprint of Rhombozoan is basically a core of sex covered in a sheath of eating.  No organs. No body cavity.  I do mean blueprint as each species has a prescribed number of cells from 8 to 40 depending on the species.

The adults attach to the renal sac wall with distinct head region termed a “calotte” (the reference for the spinning top).  Once attached, the outer cells of the Rhombozoan do not actually feed on the cephalopod but with use their cilia to move small particles and nutrients in the urine near themselves to feed upon.  While the adults are attached, the young swim free to fully explore all the nooks and crannies of the cephalopods renal system or in special cases venture out into the outside world.  Allegedly, Rhombozoans do not hurt their molluscan hosts. However if things get crazy and the Rhombozoans start inviting all their friends like it’s a Snoop and Dre party, the cephalopod may experiences some renal “blockage”.

The reproductive cycle is well…ahem…complicated.  Sex, no sex, or switch between the two?  Some Rhombozoans may start off reproducing asexually but when the cephalopod reaches sexual maturity, then the Rhombozoan decides to switch too.  Sometimes love is in the air….or urine.

A single cell runs along the axis of a Rhombozoan, creatively called the axial cell.  The axial cell contains little undifferentiated Rhombozoans called axoblasts.  These axoblasts can differentiate into just about anything—kaiju, a new car, a pot of gold, hope—but most likely an adult.  In asexual adults these axoblasts can give rise to either asexual or sexual forms.  The process is long, twisted, and involves multiple steps, like getting anything approved at my university.  When sex is preferred, the axoblast becomes an infusorigen, basically the Tootsie Roll Pop of the reproductive phase with an outer layer of eggs and a center of sperm.  These inner sperm eventually fertilize the outer ova.  The infusorigen larvae actually leave the cephalopod.  Where? Nobody knows. I’m guessing Vegas.

The simplicity of the body plan versus the mind-boggling intricacy of reproduction also tells another tale.  Most parasites transition through several forms allowing them to move between different hosts and sometimes free living.  The classic example is cestode parasites that require time parasitizing copepods, fish, and eventually birds.  Some of these parasitic phases become biologically “simple” and may lose their organs, guts, mouths, and any number of other unnecessary parts.

The adults of Rhombozoans are simple and the complicated life cycle of Rhombozoans seems very indicative of a parasite.  Yet, the paradox is that Rhombozoans are only known from cephalopods.  Unlike other parasites with these specialized forms and complicated lives, Rhombozoans seem to have no other intermediate or final hosts.  Maybe at one time Rhombozoans actually did move between hosts.  The cephalopods are an ancient group surviving through the extinctions of many marine organisms. Conceivably, at one point Rhombozoans took vacations in the renal systems of a Mosasuar or other giant ocean predator.  When these giant predator went extinct, Rhombozoans evolved and stopped touring other renal systems.

The post Reese’s Cups, Octopus Urine, Prehistoric Giant Marine Reptiles, and Parasite Sex first appeared on Deep Sea News.