TWO INJURED SEA COMBS CAN FUSE INTO A SINGLE ENTITY, AND THRIVE

I want to play "let's ___ with mama" with the shrimp I study, but they generally do not meet their offspring because of how their life cycle works. The shrimp put their eggs in the mud and then the young may not hatch for years, until some obscure shrimpy conditions are met. They live with a mixed group of strangers and relatives, some of which may be literal decades older, but not mama.

Leeches, on the other hand, carry their young on their underside. Let's remain safely attached to mama

SEA TOAD MY BELOVED

"anger fishes are nightmare fuel from the deep"

OK smarty pants then how do you explain THIS:

From this video: https://www.youtube.com/watch?v=1tMQhyATzQA

[Image Description: A red anger fish with big round eyes and a cute pouting expression she is bright red and textured.]

The first image linked is not actually a priapulid but a sea cucumber in its spawning posture! It was misidentified on iNaturalist and went viral before it was corrected— see the original observation here. (It gets kinda heated which I think is kinda funny. Penis worms are serious business!) I have always said before that I want internet fame specifically for two reasons: to make PSAs about Anomalocaris’s head carapace which everybody always leaves out of drawings because of that one inaccurate museum model, and about the incorrectly identified sea cucumber photo about which is now like the first image result you get when searching for penis worms and is my NEMESIS 😠 (the misinformation, not the photo or the sea cucumber, those are great)

For all the worm fans— priapulids are super easy to identify; there are as of the time of writing only 22 recognized species, and for many of them the only photos of them are from articles in scientific journals. Over half the species are microscopic, and the macroscopic ones are mainly found in polar regions, often in the deep sea, where they are usually burrowed in sediment and thus are little-encountered by people. The only one of them that is commonly photographed (and studied) is Priapulus caudatus, which is broadly found across the northern northern hemisphere even in shallow waters and I think probably has to be the most accessible species in general. They look like this:

image by Thomas Trott

This species accounts for probably 99% of the images of priapulids out there, and its relatives look rather similar, such as its southern hemisphere counterpart Priapulus tuberculatospinosus or the two-tailed species Priapulopsis bicaudatus. The intricate, feathery tails (referred to in the literature as “caudal appendages”) are probably the most distinctive feature of this group; they are believed to be involved in respiration, though as with many things about the phylum it is not known for certain. (See this recent paper for a review of macroscopic priapulid morphology.) In the zoomed-out photos of that sea cucumber you can see on the iNat page, it lacks a tail which is a dead giveaway that it is not any of these; also note that while it has some longitudinal striations along what sorta looks like a proboscis, they don’t actually bear any teeth! The spined, toothed proboscides of priapulids are indeed super cool and are their most distinctive feature setting them apart from other proboscis-bearing worms like peanut worms or spoon worms, which are often also misidentified online as priapulids. A fun fact is that the shape of their teeth varies across species in a way that appears to be closely correlated with their diet, see this paper for a neat study that uses tooth shapes to examine the different ecological niches occupied by extant priapulids and their Cambrian relatives!

The only other macroscopic priapulids that don’t look much like Priapulus are the two species Halicryptus spinulosus and Halicryptus higginsi, the latter of which I believe there are literally like two full-body photos in existence of it, one of which is from a login-walled journal article from 1999 and the other of which is one of the specimens from that 1999 article photographed after 25 years preserved in a museum. There’s a decent number of photos floating around of H. spinulosus (though still not as many as P. caudatus); they look like this:

image by Claude Nozères

As you can see, Halicryptus lack tails and have a much less prominent proboscis than Priapulus and its relatives, which you can only see the spines of on the very tip; H. spinulosus in particular has a rather short and small body that distinguishes it a lot, while H. higginsi is the largest known species of priapulid in the world (see this paper for a review of both of them). They’re maybe less distinctive-looking but idk, I don’t know off the top of my head if there’s super anything else you would mistake them for, and images of them are pretty uncommon anyway. In any case as far as macroscopic priapulids go, these are the only ones you have to look out for; if you’ve got those down you’re all set! As stated before, most priapulid species are actually microscopic; just for fun here’s the tropical meiobenthic species Tubiluchus corallicola:

image by Museum of Comparative Zoology, Harvard University

look at that squiggly tail!

And yeah in conclusion priapulids are super cool and underrated and I wish there were more people paying attention to them; there’s soooo many neglected taxa that we’re still only just discovering basic aspects of their biology and priapulids are one of them! If you want to see their amazing extensible proboscis in action, linked below is by far the best priapulid video out there, I highly recommend it. And most of all remember everybody THAT PHOTO IS A FRICKING SEA CUCUMBER, NOT EVERY WORM THAT LOOKS LIKE A PENIS IS A PENIS WORM AAAAAAA 😭😭😭

Can't believe any real animal has teeth as awesome as penis worms have.

They are meat eaters :)

their hair makes them look so round and fat

On a more philosophical note, in general it's still very up in the air what conscious experience "is"; I know neuroscientists have proposed various theories of consciousness attributing it to various cognitive processes like multisensory integration, associative learning, working memory, etc. I haven't read all that much of the literature to know what the scientific consensus is on those theories (I don't think there isn't one) but my own personal (unsourced but I don't think very controversial) guess would be that it probably involves all of those things, and also probably that consciousness is a spectrum, not just a yes-or-no thing (cf. how it feels like to be fully awake vs. in the middle of falling asleep vs. dreaming). I don't think we'll ever really be able to prove or know for sure "what it feels like" to be a fruit fly or whatever, but strictly speaking this is technically the case even with other people, right— you can't do a brain scan to find a person's subjective experience, cuz it's well, subjective; yknow there's all the classical debates about philosophical zombies and the Chinese room thought experiment and so on that philosophers have talked about. Ultimately I think people intuitively ascribe consciousness to others because yknow they have a theory of mind, like I don't think I could be a solipsist even if I wanted to. When we anthropomorphize animals (or inanimate objects 😜) this is what we're doing; we view them and recognize aspects of ourselves, accurately or not, just cuz it comes more or less naturally. From a scientific perspective I think that's basically all we can really do, is to observe animals in a rigorous manner and see what they can do, and idk from the results we do have, at least to me it sure looks a lot like these animals have consciousness. They process complex sensory information in real-time, they form novel behaviors based on experiences in context, they display signs of emotion in a statistically quantifiable way, idk what do we call that if not subjective experience?

It's always so weird to come down from the biology heavens to see what the average person believes about animals, plants, ecosystems, just the world around them. I don't even mean things that one simply doesn't know because they've never been told or things that are confusing, I'm talking about people who genuinely do not see insects as animals. What are you saying. Every time I see a crawling or fluttering little guy I know that little guy has motivations and drive to fulfill those motivations. There are gears turning in their head! They are perceiving this world and they are drawing conclusions, they are conscious. And yet it's still a whole thing if various bugs of the world feel pain or if they are simply Instinct Machines that are Not Truly Aware of Anything At All????? Help!!!!!! How can you look at a little guy and think he is just the macroscopic animal version of a virus

scientists: oh hey we found a new species of deep sea feather star, neat :)

the news: TERRIFYING and ALIEN creature with ONE THOUSAND ARMS discovered LURKING in the DEEP ABYSS of the sea

the public: omg im never swimming in the ocean again!!!

the animal:

If your girl has

bulbous eyes

piercing-sucking mouthparts (beak)

raptorial legs

cogwheel-like structure

that’s not your girl that’s wheel bug!

(photo from this article)

oh oh speaking of fruit fly behavior, I hadn't seen it when I reblogged this post before but someone mentioned it in the tags— just last month there was a super super neat paper published describing play behavior in fruit flies! Basically they put a bunch of fruit flies in containers with food and a rotating carousel embedded in the floor (which they could walk on and off at will) and then used motion-tracking software to quantify how much time the flies spent time in different parts of the container and how they moved between them. The researchers found that while most of the flies avoided the carousel, quickly leaving after going on it, about a quarter of them would repeatedly walk onto the spinning carousel and stay there for extended durations, while spending less time visiting the food patch; in further trials, where the containers had two carousels which alternately spun and stopped every few minutes, carousel-seeking flies would often stay on one carousel until it stopped and then move to the other. (I don't think it'll embed here but see the link for a video of a fly going back and forth between the two carousels!)

The researchers interpret this as the flies having individual preferences for going on the carousel, and those who did go on it were doing so voluntarily and deliberately (as opposed to e.g. accidentally walking into it and getting trapped), seemingly just because they liked it. The really suggestive thing here is that the carousel-seeking flies would do this over food: as depicted in figure 2 of that paper, the researchers found that both the control-group flies (for whom the carousel was stationary) and the carousel-avoiding flies spent around 40% of their time visiting the food patch; in contrast, the flies who rode the carousels spent only half that time at the food patch, and instead spent 24% of the observed time riding the carousel. Obviously we don't know what emotions the flies might be feeling (the authors mention that a good line of follow-up research would be to look at how dopamine/reward pathways are involved in this behavior) but it appears that there is some kind of generally positive feeling that motivates them to do this, cuz yknow food is obviously something they need and want and yet they're choosing to do this instead. They hypothesize that this kind of “passive movement” play-like behavior observed in flies and other animals could functionally serve to ‘train’ their perceptive abilities (specifically, their sense of proprioception) by providing external sensory stimulation

It's always so weird to come down from the biology heavens to see what the average person believes about animals, plants, ecosystems, just the world around them. I don't even mean things that one simply doesn't know because they've never been told or things that are confusing, I'm talking about people who genuinely do not see insects as animals. What are you saying. Every time I see a crawling or fluttering little guy I know that little guy has motivations and drive to fulfill those motivations. There are gears turning in their head! They are perceiving this world and they are drawing conclusions, they are conscious. And yet it's still a whole thing if various bugs of the world feel pain or if they are simply Instinct Machines that are Not Truly Aware of Anything At All????? Help!!!!!! How can you look at a little guy and think he is just the macroscopic animal version of a virus

“Measuring sea cucumber body dimensions and weight and determining their relationship is notoriously difficult.” — Prescott, Zhou & Prasetyo 2015

“Tagging sea cucumbers is notoriously difficult because of their plastic nature and autolysis capacities.” — Gianasi, Verkaik, Hamel & Mercier 2015

“Nevertheless, marking and tracking sea cucumbers is notoriously difficult and represents a serious challenge.” — Rodríguez-Barreras, Lopéz-Morell & Sabat 2016

“Obtaining accurate but non-destructive mass and morphology measurements of holothuroids is notoriously difficult because they readily change shape and retain water in their body cavity.” — Munger, Watkins, Dunic & Côté 2023

the notoriously difficult cucumber

image by Amaury Durbano