#in line with the denticles of course

[alyanas-little-hideout]

and gently pet that soft lil spot right above his eyes

Did you guys know that the most recent version of sharks have fins that are kinda leg like and they like to walk up onto land?

[alphynix]

Strange Symmetries #15: Serrated Saw-Snoots

Long flattened snouts lined with pointy tooth-like denticles have convergently evolved at least three separate times in cartilaginous fish: in modern sawsharks and sawfish, and in the extinct sawskates.

This repeated "pristification" suggests that saws are just incredibly useful and relatively "easy to evolve" structures for these types of fish, being both highly sensitive to bioelectric fields and able to physically slash and stab to kill prey.

Onchopristis numida was a sawskate known from what is now Northern and Western Africa during the mid-Cretaceous, about 95 million years ago. Up to about 3m long (~10'), it lived in both saltwater and freshwater, and was probably a bottom-dwelling ambush predator similar to modern angelsharks.

Whenever a denticle was lost from its saw, a larger one would grow to replace it, and over the life of an Onchopristis this resulted in an increasingly extreme amount of saw asymmetry.

Modern pristified fish also have rather asymmetrical saws. Sawfish are commonly born with a different number of denticles on each side, while sawsharks add extra denticles of varying sizes as they age, with the ongoing replacement of lost denticles resulting in more uneven arrangements over their course of their lives.

It's not clear if the asymmetry gives any sort of advantage to these fish – but if nothing else it probably doesn't cause them any disadvantage, so there's no evolutionary pressure to stay more symmetrical.

———

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[danbensen]

On one earth, fish crawled out of the sea. No, not those fish.

The line that would give rise to the sharks and rays also produced the xenacanthids: long, slippery, venemously-spined creatures that hunted the brackish bayous of the late Devonian. This was just when land plants had evolved to the point where they could support an ecosystem of prey. Shark-like predators waited in ambush at the edges of shallow ponds, lunging forward on their front fins to snap up passing invertebrates. These powerful fins were also useful when the pond dried up.

The problem with life on land is that it weighs a creature down. Air does not support flesh the way water does, so a terrestrial animal must evolve a rigid support structure. The xenacanthids did, but not from their flexible, cartilaginous skeleton. Instead, successful land-walkers were those with stronger and larger denticles on their fins. These tooth-like skin structures grew and fused into plates, interlocking aground the legs, fanning out across the chest and groin, and rising to cup the torso. Like their invertebrate prey, the fish evolved exoskeletons.

Imagine the following diversification and extinction events. Terrestrial sharks occupied every niche, from runner to flier to burrower. On one earth, they grew very large.

For this lineage of giant herbivores, eyesight became a problem. Through one evolutionary misadventure or another, these placid browsers could not see well enough to defend themselves from predators. Predators of course took advantage of this sensory deficit, and the most successful grazers were those that cultivated a relationship with sentries.

A species of small flying animal—not in fact anything like a lizard, but a kind of terrestrial shark—lived on the backs of the large browsers. These lizard-birds fed on the parasites that lived between their hosts' armor plates and gill-flaps. And they had excellent vision.

The reader can probably imagine at this point the selective pressures that followed. Predation pressure assured that the tight lines of communication evolved between grazer and flier. Environmental change rewarded those grazers with more complex, cooperative behavior. Larger, more interdependent herds necessitated some means of rapid communication, and there were already these flocks of fliers everywhere.

Flocking behavior is one of the classic examples of emergence.1 Even a simple set of rules enacted by tiny-brained individuals can branch out into impressive feats of calculation on the level of the whole flock. Memories can be kept, strategies can be passed on, events can be simulated in the flock, and the resulting plan enacted to gain real-world prizes. Swarm intelligence, the hive-mind, is known in many Convention species.

This species called itself the Bucolics. The cow-turners.

read on

Picture by Timothy Morris

[clannfearrunt]

in which i lost my mind for several hours over nudibranch mouthparts

ok. so the video True Facts: Freaky Nudibranchs just casually mentions nudibranch beaks. There’s a photo in the video, credited to Dr.Jeffery Goddard:

Having done a normal amount of googling about nudibranchs, their diets and mouthparts a few months back, I was like, what the fuck??. I was previously only aware of nudibranchs having a simple mouth opening and a radula to eat with. Well, no big deal, there’s plenty of shit I don’t know a damn thing about, and we find new things every day! 

So I start googling variations of “Nudibranch beak”. Of course, nothing comes up other than results talking about nudibranchs (beakless) and cephalopod or bird beaks on the same page. I try looking up Dr. Jeffrey Goddard. I don’t remember what I found initially but my friend did later bother to locate his profile on researchgate. Does a lot of nudibranch stuff

I get distracted from that for a sec and, on a whim, search “Nudibranch jaws” instead. I come across a single line on wickeddiving.com:  

“For example, many dorid nudibranchs (Suborder Doridacea) have broad radulae with numerous teeth for grazing on sponges, while most aeolid nudibranchs (Suborder Aolidacea) have narrow radulae and strong jaws for feeding on hydroids and bryozoans.”

Why would you not ELABORATE on the JAWS. 

Anyways I start searching “Aeolid nudibranch “jaws””. I start having slightly more luck. Actual research papers describing nudibranchs, some of which have scans or illustrations of the jaw structure, and an old website from Earlham College which has a single sentence mentioning the existence of jaws. 

I found a relatively easy to tell what the fuck im looking at image within “Description of a new aeolid nudibranch (Mollusca: Opisthobranchia) belonging to the genus Phidiana” by R. C. Willan (that’s the url it says to link but if that doesn’t work then [here’s] the direct pdf link). On page 6, there’s these illustrations; we are focusing on 13, 14, and 15:

“13, entire left jaw laid fiat showing inner surface; 14, detail of jaw's hinge; 15, enlargement of border of masticatory process...“

“Jaws (Fig. 13) ovate; strongly convex on outer surface; anterior end broadly rounded; posterior end elongate. Hinge region of both jaws thickened (Fig. 14); apical thickening of jaws consisting of a short ridge aligned parallel to dorsal margin and a single, strong projection that is directed vertically downwards. Masticatory process very thin, relatively short (about one-quarter length of dorsal margin); its outer border bears a single row of 12-15, rounded, lightly cuticularised denticles that are fairly even in size (Fig. 15)“

Ok. So. Based on that and the initial photo that spurred this entire quest, I assume that these fuckers have horizontally connecting jaws? Other mentions I could find of jaws on Nudibranchs were all also papers, which I had an easier time finding by switching to searching “Phidiana jaws”. [paper 1] [paper 2] (lost the links to papers 3 and 4 but they were also describing new-at-the-time species). My second guess is that it’s only Aeolid nudibranchs that have jaws, as every nudibranch whose jaws I could find were aeolids, and the couple of dorid nudibranchs I read the original descriptions of only had their radulas included, and no mentions of a jaw. Here’s a photo of Phidiana lynceus, a slug in the same genus as the one that jaw I posted up there belongs to:

After I briefly mentioned this Quest on the blog, I was notified that many other gastropods, like land snails and freshwater snails also have similar mouthparts. This, unlike the nudibranchs, was easy to find. [A Microscopic Look at Snail Jaws] [Apple Snail Digestion]

My question, after all that, is this: Why was this information (about nudibranchs) so hard to find. You would think it wouldn’t be difficult for more sources geared towards laypeople to mention that some nudibranchs have chitinous mouthparts in addition to the radula. 

It’s been 2 days and I’m still thinking about this.

[astroi]

"Proliferation Contretemps."

(Part 1)

The fights we, the ninja and my father, have can get a little bloody, but luckily I handle most of the hand-to-hand combat.

“It’s seems like you’ve improved from our last fight, Green Ninja. Have you been practicing?” Garmadon and I circled another like two predators battling for a territory - not completely untrue.

“Yeah, how’d you tell?” I kicked him in the gut. He retaliated with an uppercut to my jaw. Always the damn jaw.

I had to resist saying, “Aw shit man, not again,” instead going with a reliable, “Ow!” Yet another tooth came flying out, the same one as last week.

I glared, “Do you always have to go for the teeth?”

He laughed, “I’m surprised you have any teeth left to lose, Green Ninja.” He paused to study the fallen denticle, “Didn’t you already lose this one?” He held it in his palm as if recognizing it as one of his own.

I, tired and fatigued, admitted, “Yeah, what’s it to you?”

“It’s an implant.” I added to remedy my fears of him maybe connecting the dots.

“This would be some high quality dentistry work, if you were telling the truth.” The sweat formed from our battle pressed my blond hair on my face; I brushed it back under my mask.

“Of course, I’m telling the truth; I’m a ninja.” I spat out some blood. He blinked at it as if seeing it for the first time.

“Aren’t ninja supposed to deceive?” Lord Garmadon scoffed; kids these days: throwing around the word ‘ninja’ willy-nilly.

“Awfully sangria for human blood, isn’t it?” I stared at him blankly.

He clarified almost smug, “Your blood is mulberry-colored not red, Green Ninja – or should I say, ‘La-loyd?’”

I paled, either from the blood loss or the shock, “I-I, what? What are you saying?”

Before I knew it, he had me in a bear hug – or a regular hug? Pressing my arms against my sides, he pulled my mask off with his spare hands.

“Hey! What are you doing?!” He held me so tightly, I wasn’t sure if he’d ever let go.

“We’re done fighting, La-loyd.” He gazed at me with such relief in his eyes as lava-borne flames trickled down his cheeks. The anger and tension on my face had vanished in favor of confusion. I didn’t know what to do; Uncle never taught me about this type of situation, so I rested my head on top of the crook of one of his elbows.

I looked up at him awkwardly, “Can you, um, put me down?”

“No,” His tears landed on me; they didn’t sting like I thought they would, “Not yet.” He held me closer. I couldn’t find it within myself to struggle; I sort of wanted this too.

He set me down soon enough, but didn’t let go. I tried to blink the tears out of my eyes, but that just caused one to escape. Its lime glow alerted Garmadon to it.

“La-loyd?!” His grip dropped, I jumped backwards to regain some distance.

“You’re hurt!” I frowned, and then continued searching for my mask, for it held my headset.

“Yeah,” I retorted with a bitter tone, “You caused that, remember?” In the corner of my eye I saw it, while I completely ignored the hurt expression on his face.

“And, it’s ‘Lloyd’, Dad, not ‘La-loyd.’” I rushed towards it; I had to contact the others.

“No, L-L-O-Y-D; I should know, I named you.”

He noticed me moving toward it, “Hey, stop moving while I’m talking to you, La-loyd.” I picked it up and whispered, “We’ve got a code: yellow.”

On the other lines, they were still occupied with the Shark naval and land forces.

Zane was the first to reply, “Oh no, a code yellow!”

“Oh man, that sucks.” Cole stated bluntly.

“Yeah, sorry, dude.” Nya’s response was muffled somewhat by the water spraying out from her mech.

“A code yellow?! What’s a code yellow again?” Jay asked between breaths.

“So your dad knows? Do we need to fetch you, bro?” Kai confirmed.

“La-loyd! Stop contacting your little ninja friends, and listen to me when I’m talking to you.” The Secret Ninja Force heard Garmadon as he swiped the garb from me, his son.

“Give that back, Dad!” I tried to take it back from him, but he was taller than my max jumping height. He grabbed me and I sunk my teeth in him before I could really run that plan by me.

Despite that, he didn’t let go, which just made me feel more like a ‘Garmadon’ than I had all week, “Uh, sorry. I don’t know what came over me.” I mumbled looking away, unable to rub the back of my neck, I hadn’t bit anyone since I bit Chen in third grade. I wasn’t certain, but biting people didn’t sound very befitting of a ninja.

“Those are good instincts, La-loyd; but your venom doesn’t work on me.” Had he just encouraged me to bite people?

“Ve-venom?” That explained so much, and yet so little. Had that been the reason Chen was sent to the hospital when we were younger?

“Is that why Chen hates me!?” I blurted. Whoops.

Dad hummed as he adjusted his grip and started walking toward his mech, “I don’t know who this ‘Chen’ is, but if you bit him, probably. Our bite, albeit non-fatal, inflicts excruciating pain to its victims.”

“Oh, I said that out loud. Um, I,” I didn’t tell anyone, not even Uncle Wu, about it; but I guessed that someone like Garmadon would probably understand more than he would, “bit him in third grade after he hit me for, uh, having fangs – they had just grown in. He was sent to the hospital afterwards; I thought I gave him rabies or something.” I chuckled a little.

He joined me in my laughter, “Not rabies, but you did give him a neurotoxin.”

“Aw, man,” I groaned, “No wonder he hates me.” He set me down in the spare seat of his upgraded Shark mech; was he suspecting this for awhile? The clicks of the locks on the seatbelts snapped me out of whatever trance or dopamine-induced civility I was just in.

“Uh, where are we going?” I managed to ask when he turned the mechanical shark on.

“I’m going to get your teeth and other wounds cleaned up and – I don’t know – have you spend the night at my place. I’ll call your mother in the morning when I decide on what to do next.”

“You can’t be serious. I can’t ‘spend the night at your place.’ Mom’s gonna kill me!”

“Well, I can’t send you home as you are now that I know who you are. Not in good conscience.”

I squirmed, “You’re evil! And, not to mention, you ruined my life!”

He pressed a button on his console and said rather calmly, “Retreat! We got what we came for! And someone spruce up the guest bedroom on my floor!”

He turned back to me, “How could I ruined your life; I wasn’t even there?”

I hissed in anger. Realizing my mistake, I covered my mouth in shame; Garmadon drew a monstrous side out of me that I tried so hard to push down. He chortled at my embarrassment.

The sun had just set when we arrived at his volcano lair, I gulped when he parked in one of his docks. There was no retreating, so I followed him to a room in the medical wing where he dropped me off.

“Dinner will be ready in an hour, La-loyd. I’ll show you to the dining room then.” He looked guiltily at the bruise forming on my jaw, “Let them treat you, it shouldn’t take too long.” He closed the door.

“Okay.” I wasn’t in a position to really object.

By ‘too long,’ I wasn’t expecting it to take well over 45 minutes.

It started with a skittish medical assistant entering the room, taking my vitals, handing me a plastic cup to urinate in, and then telling me that the doctor will be in shortly.

After that, the doctor arrives in a lab coat that was covered in dark red splotches. She had exam gloves on and her hair tied up in a bun like she was fresh out of surgery.

“Well, hello there, La-loyd.” She greeted me like I was a small child and mispronounced my name like Garmadon – or was that actually how he intended for it to sound?

“Hi.”

“Today, will be taking some blood specimens as we do an overall check-up.” She discarded her gloves into the biohazard bin and pressed a button on the wall. She grabbed a popsicle stick and approached me.

“Open wide, say: ‘Ah.’”

“Ah.” She pressed it to my tongue and nodded.

“Okay, I’m going to disinfect your wound.” She applied a black gel to the gap that was already filled with the beginnings of a new tooth. The gel was cool to the touch for a couple of seconds before it morphed into a burning sensation.

Fiery tears fizzled as they formed and fell, “If it burns, it’s cleaning the area. She filled a paper cup with tap water and looked at it for a moment as if to be debating something in her mind, and then she flung its contents at my face. A loud sizzling sound erupted from my face as my molten tears hardened into some sort of green silicate. She plucked some off my cheeks with a pair of plyers and dropped the gem formations into the cup. She filled another cup with water and handed it to me.

“Swish once the aseptic gel’s done.”

“Can you flick your tongue for me?” I frowned but otherwise complied. I hadn’t done so in years, so the rush of smells that followed overwhelmed me for a second. The blood, the bleach, my sweat; I gagged.

“Oh my, are you okay?” She threw the wood away into the same red bin as the gloves.

I swallowed, “I’m fine. I just wasn’t expecting it to smell so bad.” I flinched when I heard her write something down on her clipboard.

A male nurse entered with a vile and a few needles. She spoke low to the nurse, “Don’t blow any of his veins; in case you forgot, he’s the boss’s kid.”

“Oh, and Mr. Garmadon? We noticed that you’re behind on your vaccines, so we’ll gladly give them to you – your father already consented.”

“What? How would you know that? Do you have access to my medical records?”

“We have our ways.” Hacking, no doubt.

“Are, are you charging for this?”

“Not at all; you’re Lord Garmadon's son. Why would we charge you? Besides, I doubt you have any money to pay with anyway.” Not wrong; I didn’t even have my phone on me – it was still at Wu's with the rest of my clothing and school stuff.

I shrugged as the nurse drew a vile of reddish purple blood. He balked, “You really are the boss’s kid, aren’t you?” I pinched the bridge of my nose and looked up at the security cameras in the corners of the ceiling.

“Ugh, don’t remind me.” He rolled up the rest of my sleeves to give me my flu shot and my Hepatitis A shot.

After he placed the last band-aid and gave me an ice pack, Garmadon entered. Everyone, even the doctor, began to cower. My arms ached too much to move them into any battle stance. I tightened my grip on my icepack; it was starting to burn my hand.

“We-we did everything you requested, Lord Garmadon.” She bowed, he seemed to ignore her in favor of me.

Our eyes met briefly, “Even his vaccines?”

“Yes, sir.”

He stared at me, “Is this true, La-loyd?” Why was he going to take my word above his employees? We were battling not even an hour ago.

I showed him my bandages. He grabbed the hand I wasn’t using to hold my icepack to my face.

“Okay, La-loyd, let me show you where our dinner is.” After we left, there was a collective sigh that came from the room.

After several minutes of silent walking, we stopped at the dinning room. There were only two plates set on the table, despite its length suggesting it could hold at least twenty.

“Here we are, La-loyd! Take a seat right there.” The warlord pointed to a leather seat adjacent to the plate at the head of the table. I sat, but I didn’t bother masking my discomfort.

Garmadon clicked the microphone on his clothing, “Bring the food out!”

He cleared his throat indicating he was about to engage us in small talk, “So, La-loyd, how’s school treating you?”

I moved my chair away from him slightly, “It’s cool.” I said dismissively.

“What about your ninja friends? Do they treat you well?”

“Why do you care? But, yeah, they’re all I’ve got.”

The food came disrupting his window for a response. It was blue lobster with a butter glaze. It came with a side of popcorn shrimp and calamari fries.

I bit my tongue once I had a fry in my hand hoping he wouldn’t notice.

“Why are you doing that? Just eat your food; it's not poisoned or anything.” He noticed.

“Why am I doing what?” I ate a fry experimentally, “Is this squid?”

I bit my tongue again; the food smelled fine.

“Yes, but why are you biting your tongue like that? Are you trying to suppress your instincts?”

I wanted to tell him, but he never had to hide what he was. “What instincts?” I lied poorly.

I narrowed my eyes mumbling, “Well, that’s none of your business anyway, Garmadon.”

“Son.” My eyes darted to him, pupils slits before dilating again.

“You wouldn’t understand.” I ate one of the shrimp; not too shabby, could use some lime juice.

“Or would I?”

I glared, “No, you wouldn’t understand what it’s like for people to be constantly comparing you to someone you’re not.” I cut vigorously into the lobster’s shell. As bits broke off, it made loud crunching and crackling crashes. I winced.

“For people to see you as nothing more than a monster.”

“When people see me, all they ever see is you!” I clenched my fists. The floodgates were open, I couldn’t stop myself from venting.

“To have to constantly push down what feels natural, just so you can go a single day without being picked on or people pointing at you and saying, ‘I bet he’s as evil as his dad,’ or ‘Why haven’t those ninja killed him yet?’ Or, ‘Ninjago would be better off without him around.'” I rubbed the tears out of my eyes, the flames dancing on my hands was almost enough to distract me from the memories I was reliving.

“No one was there to tell me that it was normal to react the way I had.”

“La-loyd, I didn’t know.” He put a hand on my shoulder. I inched away some.

“Of course you didn’t know, you said it yourself: 'you weren’t even there!' You never bothered to know! I lived my whole life feeling like a freak. It sucks to despise your reflection and what you are!”

I started eating a large portion of the lobster, shell and all. It was oddly calming to bite into something crunchy. Garmadon watched me with worry in his eyes.

“I, you’re right.” He broke the silence.

“That it sucks?”

“Yes, that, but also that I should’ve been there for you when you were growing up.”

He grimaced, “But I wasn’t. I’m sorry, La-loyd, but we’re together now.” He squeezed my arm, but it was still tender from the flu shot. Maybe the pain was making me more aggressive than I usually was; Oni blood was weird like that.

“We’re not 'together now.’ Did you seriously think that I would move-in with you just because you captured me?”

“I just thought I could make things right. We can finally make up for lost time. There’s so much I can teach you: how to tie a tie, ride a bike, and, if you're feeling up to it, conquer a city!”

I always wanted someone to be there and do those things with me - well, not the last one - since my mom wasn’t there either, but I never saw that person being Garmadon. It was clear that he was only trying to butter me up to helping him conquer Ninjago. Of course, what was I to expect from an evil warlord?

[autodidact-adventures]

Marine Life: Stingrays

Kimgdom: Animalia

Phylum: Chordata (animals with a notochord for at least part of their life; a notochord is a flexible rod made out of a material similar to cartilage).

Subphylum: Vertebrata

Class: Chondrichthyes (cartilaginous fishes)

Subclass: Elasmobranchii (this subclass includes sharks, rays, skates and sawfish).

Superorder: Batoidea (rays)

Order: Myliobatiformes (one of four orders of batoids).

Suborder: Myliobatoidei (one of three suborders).

There are eight families of stingrays.

Most stingrays have a barbed stinger (or more than one) on their tail, modified from dermal denticles.  It can be up to 35cm long, and is used in self-defence.  The underside of the stinger has two grooves with venom glands.  The actual venom is concentrated in the integumentary sheath – a thin layer of skin that covers the stinger.  There are a few stingray species (e.g. the manta & porcupine rays) that don't have stingers.

Stingrays are commonly found in tropical & subtropical coastal waters, all around the world.  Some are found in warmer temperate oceans, and others in the deep ocean.

The river stingrays (family Potamotyrgonidae) are only found in fresh water; so are some of the whiptail stingrays (family Dasyatidae).

Most stingrays live in the 2nd-lowest zone of the water column (they are demersal).  However, some of them live in the pelagic zone (they are pelagic), such as the pelagic stingray, and the eagle rays (family Myliobatidae).

Behaviour

Because they're so flat, stingrays can hide very easily – they agitate the sand and then hide in it.  Their eyes are on top of their bodies, and their mouths are on the underside.  Therefore, as they actually can't see their prey, they use smell and their ampullae of Lorenzini (electoreceptors similar to what sharks have) instead.

When feeding, stingrays settle on the sea floor, with only their eyes & tails visible.  Their favourite feeding grounds are coral reefs, and during high tide they share them with sharks.

Reproduction

For some stingray species (e.g. the round stingray or Urobatis halleri) use their ampullae of Lorenzini to sense certain electrical signals that mature females give off.  When he courts a female, he follows her closely while biting at her pectoral disc. Then, he places one of his two claspers into the female's valve.

Female stingrays bear their young in litters of 5-13 – they are ovoviviparous, which means that the embryos develop in eggs, and stay in their mother's body until they're ready to hatch.  The eggs stay in the stingray's womb, and there is no placenta.  The embryos absorb nutrients from a yolk sac.  After the yolk sac has been depleted, the mother provides uterine “milk”.

Female rays can store sperm for two years and not give birth until they decide the time is right.

Diet

Various stringrays have various ways of eating.  Some have specialized jaws that they use to crush hard mollusc shells.  Some have cephalic lobes (a type of external mouth structure) to guide plankton into the oral cavity.

Stingrays that reside on the sea floor (they are benthic) use a strategy called tenting.  They wait until the prey comes close, then press their pectoral fins against the substrate and raise their head.  This creates a suction force that pulls the prey under their body.

Stingrays have a wide variety of colours & patterns on their dorsal surface: this helps them to camouflages themselves in the sand.  Some stingrays can change colour over the course of several days, in order to adjust to a new habitat.

For most stingrays, their main foods are molluscs, crustaceans, and occasionally small fish.  In the Amazon, freshwater stingrays eat insects, breaking down the exoskeletons with mammal-like chewing motions.  Some large pelagic rays (such as the manta ray) use ram feeding to eat huge amounts of plankton; some have been seen swimming in acrobatic patterns through plankton patches.

Stingrays and Humans

Stingrays can be caught with fishing lines or spears.  Dried wings are the most common stingray dish around the world, but there are many different recipes.  In Mayalsia & Singapore, the stingray is usually grilled over charcoal, then served with spicy sambal sauce.

The flaps (wings) are usually the most prized part of the stingray, as well as the cheek (area surrounding the eyes) and the liver.  The rest is considered to be too rubbery to eat.

Stingrays are usually docile and curious, not aggressive.  They will usually flee any disturbance, but sometimes they brush their fins past a new object they've encountered.  However, some of the larger stingray species are more aggressive.  Their stinger, which they use for defence, can cause injury or even death.

Divers and snorkellers can find stingrays in shallow, sandy waters, especially when the water is warm.  (Swimmers usually can't see them.)  There are sites where humans can swim with stingrays and even hand-feed them, such as in the Cayman Islands, Belize, many Tahitian island resorts, and the Caribbean island of Antigua.

Because stingray skin is hard and rough, it is often used for the under layer of the ito (cord/leather wrap) for Japanese swords.  Some museums show arrowheads & spears made from stingers, used in places like Micronesia.

Stingray Families

Butterfly rays – Gymnuridae

Deepwater stingrays – Plesiobatidae

Eagle rays – Myliobatidae

River stingrays – Potamotrygonidae

Round rays – Urotrygonidae

Sixgill stingrays – Hexatrygonidae

Stingarees – Urolophidae

Whiptail stingrays – Dasyatidae

[Source]

[coyote-carnage]

lithokitty hat auf dein Foto geantwortet: the boys are back in town

Please tell us about the big dude, he intrigues me!

That’s Emeron! He’s an obsidian Byranthian. Byranthians are large, territorial demons that exist between the 77th and 81st lines (deep; the Purgatorium is measured vertically, sea level is around the 45th line). Obsidians are the larger of the two subspecies, amethystines being the smaller. Aside from size, they are easily identified by their rough skin--made of dermal denticles--their aposematism, their quadrupedal gait, and their lack of eyes. They have the ability to spit gastric acid, made more dangerous by their consumption of sulfur during mating seasons. Though they typically walk on all fours, they are fully capable of standing or sitting upright.

They’re considered one of the more “primitive” of the Purgatorium species because of their lack of government, language, or unified identity. They communicate through hums, snorts, chirps, and clicks. However, they are highly sensitive to changes in climate and wartime, and will adjust accordingly and will even lend aid to constituents in a war. They have complex social groups called fleets that consist of 20 to 50 adults.

Emeron is extremely small for his kind (sizing up to 8′6″ standing upright, weighing in at 615 lbs), and was rejected by his fleet as a juvenile. Because of this, he had to escape the 77th line and move upward in order to eat and not get attacked by larger Byranthians. But because Byranthians are not adapted to hunting on the surface, he nearly starved. Etomane found him on a trade route and decided to temporarily take him in, nurse him back to health, then release him. Of course, Emeron became very attached to Etomane, and again Byranthians are territorial, so he refused to leave Etomane’s shop. And he’s been there ever since.

[shesurfs1]

In the way of progress

It was another in a string of sunny weekends. The beach was crowded when Gretchen, Sue, and I arrived at noon, shortly before high tide. The waves were up from the little lappers I’d been encountering: 3-4 feet, “trunk high to overhead” according to the surf app.

I put my board in the water and waded out. Suddenly two kayaks hurtled towards me on an incoming wave. Their pilots helmeted and paddling madly, the kayaks looked like twin torpedoes. I’d gotten used to surfers in the crowded waves, but usually the good ones, the fast ones, are finishing out their rides by the time they get near me. Newbies who surf in my whitewater zone don’t have much momentum, so even though they also don’t have much control, they’re not likely to hurt anyone. This was different. I was scared by these aggressive-looking projectiles.

Skirting the kayaks, I lined up and waited for a wave, but I felt surrounded. Usually a crowded day seems worse from the beach. Once in the water, I can find a space in which to surf. Today, though, the waves were breaking so close to shore that I had to watch out for wading families as I tried to pop up. I aborted ride after ride, grabbing the board and planting my heels in the sand to arrest my course and avoid collisions. There was no room to maneuver, and I was eliciting the same looks from toddler’s parents as I had just been shooting the kayakers. It was an impossible situation. I carried my board ashore and traded for my boogie board, which I could ride without putting anyone—myself included—in danger.

If I want to practice my surfing, I need to get out in the water without the beach crowds. I need a weekday morning session. So on the next Friday I ate a quick, truncated breakfast—a cup of coffee, some grapes, and half a piece of peanut-butter toast—threw my board in the car, pulled on my wetsuit, and was in the NorCal parking lot by 7:30. The surf app said 2-3 feet waves, poor conditions. The waves looked larger than that, but the app had the conditions right: I hadn’t seen waves this incoherent since winter. In the distance the water looked like sharkskin, gray and covered with sharp denticles. Wading into the waves, I was surrounded by individual grease-green peaks, ragged bits of waves all crashing on their own peculiar agendas.

Surfers talk about “organized” surf. Waves generated by storms far out to sea become coherent wave trains as they travel from the heart of the storm. Like ripples from a stone dropped into a pond, they form orderly lines of wave energy that move outward in formation. Hundreds of miles away, they hit the coast as long parallel swells, at uniform intervals.

These waves were something quite different. Generated by more local winds, they were still in the throes of their creation, as confused and contradictory as new teenagers. Around me I saw breaking sections, green humps, and colliding peaks of foam in all directions. The timing between what could be identified as actual waves was often only four to six seconds, leaving me no time to assess the oncoming one and set up to catch it. Once you’ve decided to go for a wave, you need six or so good paddle stokes to get up to speed—which takes about an equal number of seconds. There just wasn’t time, in these wacky seas, to fit that in.

I struggled with the crazy waves, having little success, for about an hour. It didn’t feel like that long—time distorts in the waves, slowing down in Einsteinian space traveler ways—but at some point my arms tired of bracing the board against the waves as they churned past me, and I knew it was time to go in.

The session left me frustrated. After the peak experience of my bathing suit session in mid-August, I’ve had almost no luck finding my feet on the board. Is winter going to come and send me back to the boogie board without any more progress than this?

[alphynix]

Transcript for the text on the image under the cut:

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Spectember 2020 #10 | nixillustration.com | alphynix.tumblr.com Concept suggested by: anonymous

Marine Temnospondyls

(Ghotiidae)

Descended from the archegosauroids, a fully aquatic group of Permian temnospondyl amphibians, the GHOTI was the closest that tetrapods ever came to actually turning back into fish.

Already retaining a rather fish-like physiology from early tetrapods, with tiny bony scales within their skin and internal gills as adults, these temnospondyls had a metabolism more like air-breathing fish than modern amphibians. While they were still facultative air-breathers using lungs to get the majority of their oxygen, their gills allowed them to stay submerged for much longer between breaths, sometimes for as much as several hours at lower levels of activity.

Like the later trematosaurids, basal ghotiids developed tolerance to saltwater and adapted to a marine predator lifestyle. But their lineage took it much further, modifying the somewhat crocodile-like body plan of their ancestors into a highly streamlined convergently ichthyosaur-like form – an ecological niche largely unexploited by tetrapods during the Permian.

Ghoti reventum, a highly derived ghotiid, reached lengths of about 4m (13'). A row of large keeled osteoderms along its spine formed a low ridge-like dorsal fin, and unlike most other temnospondyls it had polydactylous limbs with six digits each. The forelimbs formed large flippers used for steering and stabilization, and the almost vestigial paddle-like hindlimbs were kept held flush against the body, used only as "claspers" to hold onto each other during mating.

After internal fertilization and several months of development, gravid females gave live birth to litters of small larvae in shallow "nursery" waters. Just 15cm long (6"), bearing external gills and not particularly resembling their parents, these larvae didn't undergo as drastic a metamorphosis as modern amphibians do, instead only gradually changing as they grew into juveniles and then adults over the course of around 20 years.

[Image: a small axolotl-like larval amphibian with a blunt snout, large eyes, and external gills.] Larval form (not to scale)

[Image: a juvenile with a more fish-like body shape, smaller external gills, a longer snout, and its front flippers larger than its hind flippers.] Juvenile (not to scale)

[Image: an adult ghoti, a streamlined ichthyosaur-like amphibian with a long crocodile-like snout, large front flippers, a dorsal ridge, tiny hind flippers, and a shark-like vertical tail fluke. Below it a tiny larva is shown to scale, just 3% the length of the adult.] Adult ← Larva to scale

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[Image: a view of the ghoti's head with its jaws open. There are rows of extra teeth along its palate, some of which are large and fang-like.] The inside of a ghoti's mouth was lined with rows of extra teeth on the palate and thousands of tiny hook-like denticles, helping it grip onto slippery marine prey like fish and soft-bodied cephalopods.

[Image: a swimming ghoti, with close-up details of some tiny parasites on its skin and an x-ray view of the bone structure of its front flipper, showing six "fingers".] Temnospondyls usually had four digits in their forelimbs – but the ghoti’s flippers were polydactylous, with a total of six. Ghoti were often infested with “fish lice”, a type of small parasitic crustacean.