#marine animal reproduction

[quotesfrommyreading]

In 2013, neurobiologist Kristin Tessmar-Raible and her colleagues published some of the most compelling evidence of a molecular moon clock in an ocean creature. They studied the marine bristle worm Platynereis dumerilii, which looks like an amber centipede with tiny feathered oars running the length of its body. In the wild, the bristle worm lives on algae and rocks, spinning silk tubes for shelter. While reading studies from the 1950s and ’60s, Tessmar-Raible learned that some wild bristle worm populations achieve maximal sexual maturity just after the new moon, swimming to the ocean surface and twirling in circles in a kind of whirling dervish nuptial dance. The studies suggested that changing levels of moonlight orchestrated this mating ritual. “At first I thought this was really crazy in terms of biology,” says Tessmar-Raible, who notes that she grew up far from the ocean, “but then I started talking to colleagues in marine biology and realized that this might not be so uncommon.”

To learn more, Tessmar-Raible and her colleagues kept bristle worms in plastic boxes, feeding them spinach and fish food, and simulating typical and aberrant moon cycles with an array of standard light bulbs and LEDs. Worms raised in perpetual light or in entirely moonless day-night cycles never displayed reproductive rhythms. But worms reared with periodic nocturnal illumination synced their spawning rituals to the phases of their artificial moon. As suggested by earlier studies, Tessmar-Raible found light-sensitive neurons in the worms’ forebrains. And genetic sequencing revealed that the bristle worm has its own versions of essential molecular clock genes found in terrestrial insects and vertebrates. Tessmar-Raible’s conclusion is that the worms have a robust lunar clock analogous to the more familiar sun-synced circadian clock. “This is an endogenous oscillator,” she says. “Something in the body preserves the memory of those nocturnal illuminations.”

In similar studies, Oren Levy and his colleagues collected pieces of living corals from Heron Island reef and housed them in large outdoor aquaria, some of which were exposed to ambient sunshine and moonlight, some shaded at night to block all moonlight, and some subjected to dim artificial light from sunset to midnight and then kept in the dark until sunrise. Each day for eight days before the estimated night of mass spawning, the researchers collected bits of corals from the different aquaria and analyzed the activity of their genes. The corals in natural conditions spawned as predicted and expressed many genes only during or just before releasing their gametes. Corals subjected to artificial light and deprived of moonlight displayed anomalous gene expression and failed to release their gametes.

 —   The Lunar Sea

[orcinus-veterinarius]

I saw you say the breeding ban was also passed down by corporate instead of by the caretakers, but I guess I don’t see anything bad with it, at least when it comes to orcas.

I'm more than happy to be wrong, but when it comes to captive orcas, they seem to have a lot of trouble breeding and having calfs that live more than a few years. Their population is very small, and without being able to get wild caught orcas, it'd just become more shallow and imbred. Like they'd have to stop breeding at some point just because of how connected genetically they all are, so isn't it fine to stop breeding them sooner rather than later? Especially with the poor outcomes?

I'm just curious because even as someone who is very positive about captive bred animals, I didn't see an issue with stopping orcas breeding. Or did this also affect bottlenose dolphins because those guys breed pretty great and have a bigger captive pop from what I've heard?

You are right that the genetic pool was becoming quite limited for captive orcas. However, through artificial insemination, I believe it could have gone on for quite a while longer, as this allowed the exchange of genetics across continents. This is what's still being done for bottlenose dolphins, since it reduces the need to transfer animals between facilities to maintain genetic diversity. Unfortunately, activists convinced the public that AI is "sexual abuse," which is honestly a really disgusting comparison to make. Semen collection and the insemination itself are, like all medical procedures, voluntary husbandry behaviors.

It’s possible they’d eventually have to stop, but I would rather that decision came from the veterinary department than from higher-ups looking to appease the masses. Animal care staff found out about the ban along with the rest of the general population, which was really bad form.

Reproduction and calf-rearing are just so vital to orca “culture.” As I’m sure you know, their society is matriarchal, centering around a mother and her offspring (and in certain ecotypes, like the famous Southern Residents, her offspring’s offspring and other close relatives). Activists often point out that SeaWorld’s orcas aren’t a true pod, but a hodgepodge of unrelated whales tossed together. This was true at one point, but after years of breeding, their social structure is far closer to a proper matriarchal pod (particularly in San Antonio and Orlando, and San Diego as well before Kasatka’s passing) than it once was.

A final point is that people in general seem to weirdly adverse to “breeding.” They see it as a sign of a zoo/aquarium/park being “bad.” But reproduction is one of the two major goals of all animals (the other being survival), especially in highly social and highly sexual animals like dolphins, who rely on reproduction to maintain their social structure. Healthy animals have babies, with or without human assistance, and to be honest it’s more accurate to say that animals are “prevented from breeding” than to say they are “bred.”

At this point, I know it’s a lost battle. California literally made it illegal to breed orcas (and to move them or their “genetic material” in or out of the state), and nearly half of their whales live at the San Diego park. But killer whale breeding programs are alive and well in Asia, and likely will be for decades to come.

(One last salty comment— activists love to complain about captive animals being “drugged” but are strangely silent on the chemical birth control that must be used to prevent reproduction).

[happycrabitat]

Take the memory, leave the shell! Watch what happens when we return seashells to the beach & marine hermit crabs!

Seashells are so important to beaches for a whole host of reasons.

🐚Over-shelling can affect hermit crabs because it reduces the availability of suitable shells for them to inhabit. Hermit crabs rely on empty shells of other creatures for protection and shelter. When there are too few shells available, hermit crabs may be forced to inhabit inadequate shells & pollution as homes, which can hinder their growth and make them more vulnerable to predators and environmental stressors. This can ultimately impact their survival and reproductive success.

🐚Shells provide homes or attachment surfaces for algae, sea grass, sponges, coral and a host of other microorganisms.

🐚Animals such as decorator crabs and octopus use shells as camouflage and many fish use shells as hiding places to avoid predators.

🐚Shells help to stabilize beaches and anchor seagrass.

🐚Shells are used by shorebirds to build nests.

🐚When shells break down, they provide nutrients for the organisms living in the sand or for those that build their own shells. (Shells are a major source of calcium.) I’m a firm believer in when we know better, we do better. I once shelled, and then when I learned all of this, I returned all shells that were not sprayed with a clear varnish to the beach & watched the marine hermit crabs go wild changing shells that were so needed!

[feelingautistic]

Pride Month Special

Happy Pride Month to my shark enthusiasts across the LGBTQ+ spectrum! Since June is Pride Month, I thought I'd discuss the common view that being LGBTQ+ 'goes against nature' by talking about...being LGBTQ+ in nature.

In nature, sex typically serves the singular purpose of reproduction. Therefore, many animals don't engage in long-term mating like humans, instead breeding with many members of their species to spread their genes to as many offspring as possible. By this logic, same-sex relationships/mating in animals should be an unusual behaviour as the animal takes on the same costs to energy and overall fitness without the benefit of producing offspring.

That being said, over 1500 animal species have been observed engaging in same-sex sexual behaviour, many of which are marine animals. Male guppies have been observed flashing sexual displays at other males, male dolphins have been observed forming long-lasting sexual relationships with other males, female cleaner wrasses will perform the male courting rituals towards other females in the absence of males etc.

Particularly in marine animals, gender can be quite ambiguous too, with marine invertebrates commonly being hermaphrodites, capable of producing both male and female reproductive gametes (typically both sperm and eggs) which, as a result, have no distinguishable genders. Examples include coral, limpets and mangrove rivulus.

Not to mention, there are 500 fish that are known to be sequential hermaphrodites meaning they can change from being one sex to the other when necessary (for example, if the males in a population are wiped out, being able to have females become males is an excellent survival strategy). Many of you will already know that clownfish share this trait but wrasses, groupers and some gobies are also able to change their gender.

Humans changing gender and sexual orientation 'against the rules of nature' is not a reason to dismiss the idea as impossible or ridiculous. That being said, we can see that humans are not outliers in this area anyway and, without even considering land animals nor plants, we can see plenty of examples of the LGBTQ+ spectrum occurring naturally. So let's respect everyone's gender identity and sexual orientation :)

[bestanimal]

Round 1 - Phylum Gastrotricha

(Sources - 1, 2, 3, 4)

The Phylum Gastrotricha, animals commonly referred to as hairybellies or hairybacks, are a group of microscopic, cylindrical animals.

They are widely distributed and abundant in both freshwater and marine environments, though some species can be found on land living in the film of water surrounding grains of soil. Though simple, they have a head region, with a brain and sensory organs, and a trunk with a simple gut and reproductive organs. They anchor themselves to the substrate via adhesive glands and use cilia (said “hair”) to move around. They feed on detritus and have a lifespan of just a few days. Nearly 800 species of gastrotrich have been described.

Propaganda under the cut:

Fertilized eggs leave their parents by bursting out through the skin, which then repairs itself. Pretty metal tbh

Some species are capable of laying eggs that remain dormant during times when the young would be unlikely to survive, but are also capable of laying normal eggs in times of plenty.

Baby gastrotrichs just look like miniature adults (or, miniature miniature adults), and reach sexual maturity in about three days.

One species has lived up to 40 days in a lab, producing 4-5 eggs during the first 10 days of its life.

Basically a whole phylum dedicated to living fast and dying young

Idk they’re kinda cute

[iguanodont]

Mentioned briefly in my last post, but I do in fact have holographic worm stickers for sale now.

There’s far more to the world of Annelida than the humble nightcrawlers you find in your yard; many species are found in marine environments, where they take such varied forms as the fearsome bobbit worm or the ethereal tomopteris. Here I’ve rendered a ragworm (family Nerididae); a sort of polychaete (bristle worm) found in benthic marine (and occasionally freshwater) environments the world over.

Some cool facts to win you over:

1. The largest ragworm in the world is the king ragworm (Alitta virens), which ready achieves lengths of 4 ft/120 cm.

2. Ragworms are an important part of the live sea-bait industry. Unfortunately that also means they have been harvested so extensively in some areas that their populations are threatened.

3. Ragworms reproduce through a bizarre process called epitoky, in which the benthic worm either transforms into a free-swimming reproductive morph, or buds off several free swimming sex-clones to party in the world above. Either way, it will be the final act of the animal’s life.

4. Ragworms, like bobbit worms, have large, eversible mandibles in their pharynx that they extrude to give a nasty bite.

5. On the topic of ragworm jaws, the material they are made of is very strong and lightweight, despite lacking the calcium mineralization of most other animals with hard body structures. There is some research investigating its structure for aerospace engineering applications!

[auspicioustidings]

Mermen au with mer TF141 and researcher reader trying to learn about their. . .biology :Dd Or them trying to bring progressively bigger fish trying to woo and then Ghost ends up bringing you a fucking orca or some shit,

...I had to look up the reproductive cycle of several marine animals for this I hope you are happy.

Deductive Reasoning

Words: 1.3k

CW: ...light fish porn (?)

It was just fascinating. It would have been dreadfully difficult to not talk about this every chance you got and thus break your NDA if not for the fact that you never left this secure little island base. You were permitted to, but why would you want to? You were speaking with living, breathing mermen almost everyday.

4 of them, although they had alluded to their being more out there. These 4 were a... well that was the question wasn't it? Only one shark did not make a shiver, only one seal did not make a herd, only one walrus did not make a rookery and only one mandarinfish did not make a shoal. Was there a collective term for mermen? You were told you were now the leading researcher in the world for this new species, so perhaps that meant you got to decide.

Or maybe you'd just ask. They spoke to you sometimes, or at least made noises. They seemed to understand each other at least which was intriguing on its own.

It had been Soap you had met first. You had been basically abducted and hurried to this island facility where they had captured a real life merman. You were enamoured immediately by the furious thing in the tank. Half seal, harbour seal you thought. Top half looked all but human (skin must be different to allow for underwater living and ah, yes, you could see gills), hair in a mohawk (which suggested someone had cut it to look like that, who? Was it a ritual? Did they have community? Was it an emulation of human culture? Perhaps some mating strategy?), eyes somewhere between human and seal (his physicality was a similar story, he was built strong and thick, a healthy layer of fat over hard muscle).

You perhaps felt a little bashful looking back. You had been so wildly excited, asking a thousand questions and going into chaotic science mode that it took you a whole 16 hours of straight observations and notes to realise there was a creature of higher intelligence being held captive in a tank. You did, of course, apologise profusely. He clearly did not understand what you were saying, but the emotion was human enough. Bemusement.

Soap had come about because he was slippery. Well, actually he wasn't, but the story was that he was slippery. Because if the military knew you had actually been helping him escape you were probably going to get disappeared. It was lucky the facility at that time wasn't as high security, you had gotten away with it.

You had met Gaz right there on the coast when Soap went slicing through the water. You thought looking back that Price and Ghost had probably been there, just out of sight. They had come for him. Gaz was a magnificent thing. His tail was the same pattern as a madarinfish, bright orange with gorgeous blue markings. You had shown him a tin of irn-bru once with a grin and learned then that Soap could laugh. He had come right up to you and after some form of exchange with Soap had been playful, showing off his tail and holding his hand out to you. You had been existing on caffeine and noodles so hardly your fault you took it, getting dragged into the water.

Oh how thrilling an education you received in the courting practices of Dragonets! He had made quite a show of displaying his fins, including a gorgeous dorsal fin on his human looking spine. You knew you simply must see them again if only to study why Gaz's eyes were more human while Soap's leant towards seal like. He was certainly the most expressive of them. His name had only come about because you had tried every other one and he made his disdain for them very clear. By the time the merman had been rubbing what you would call his ventral fins against you, Soap had grabbed you and soundly deposited you back on shore. Just in time too for the soldiers to find you because the doctor later told you that you were in the early stages of hypothermia. Totally worth it actually.

You talked the powers that be into allowing your pet projects to free roam, after all they kept coming back to see you. Over the course of a year the facility was upgraded and a channel added from the sea to an indoor pool that would allow for better study. Soap and Gaz didn't run on a schedule exactly, but they seemed content to swim in every so often and let you poke and prod. Fascinating that they should both be half human but their other half was so entirely different. Soap was half mammal, retractable penis something he was very proud to show off anytime he was in the observation pool. Gaz was half dragonet, and while you tried to put a clutch of eggs in the pool to see if he could fertilise them he had only raised an eyebrow at you and tried once again to pull you in. Tough luck, you had learned your lesson about going into the water with them when you had met Ghost.

It had been the middle of the night when he swam into the pool. Silent, you hadn't heard him (that's where that name had come from in the end). So unsuspecting were you that you were too near the edge and his hand had snaked around your ankle, one sharp pull dragging you in after you fell to the ground (hardly avoiding a broken nose). It wasn't only his tail that was shark, he had a sharp set of teeth that he sank into the meat of your shoulder without much ceremony. His claspers had been strong as hell holding you there, the only thing likely saving you his frustration at your clothes. He must not have understood the concept very well because he released you and dove, pawing at your trousers to try and figure them out. It was an endless source of fascination for him anytime he visited after. He would lean his arms on the pool edge and just stare at your legs, tracing the outline of your body with his sharp eyes. It only seemed fair to let him look since you spent an inordinate amount of time staring at him. He was sleek and muscular, every inch an apex predator in his prime.

It was a contrast to who you would say was the leader of their group. The merman who had saved you from Ghost that first time you met him, who had ripped him away from you when his teeth had sunk into the meat of your thigh through your trousers. Price had hauled you out of the water with ease. He was part Walrus, huge and soft with a layer of blubber similar to Soap's that hid considerable strength. Of all of them his animal half was most pronounced, his canines elongated into tusks and his hair thick and whisker-like around them.

As a scientist you could not possibly play favourites. Price was absolutely your favourite. He would be still and patient with you when you were working with him. He would gently run his fingers over whatever parts of you were in reach. When you babbled excitedly he seemed to listen as best he could.

If you had taken more than a moment to really look into it, you might have realised you were not the only creature conducting research. If you had used some deductive reasoning, you probably could have anticipated that fateful day you were dragged into the sea, never to be seen by the human military again.

[bethanythebogwitch]

I am a survivor of Florida, having gone to college there for 4.5 years. There's a lot (a LOT) to not like about Florida, but the wildlife is not one of those things. So for this Wet Beast Wednesday, I'm gonna talk about the most famous Florida resident, the manatee. And why stop there? I'll discuss all the sirenians in one go.

(image: three manatees facing the camera. They are rotund, resembling a potato in shape. Their heads are smaller and end in squarish snouts. They have two flippers at the front of the head. The tail is flat, wide, and round. They are grey all over)

The sirenians are a taxonomic order of marine mammals consisting of 4 living members: three species of manatee and the dugong. They are the only herbivorous order of marine mammals, a trait that has given the the nickname "sea cows". The name Sirenia comes from the sirens of greek myth. In the original story, the sirens were bird with the heads and breasts of women, but later stories turned them into mermaids and that's the version that's stuck. There are unconfirmed stories that European sailors (the most common story uses Christopher Columbus) mistook manatees for mermaids, which is why they're named after sirens.

(image: a manatee facing the camera. Its face is visible, revealing two nostrils on a broad, flat shout covered in whiskers. It's eyes are located above the snout and are small and black. It is grey, but has patches of greenish algae growing on it)

Sirenians all have a pretty similar body plan. They are fusiform (bulky in the middle and narrower at the ends) and very bulky animals not built for speed. They don't ned to be fast (though are capable of short bursts of speed) because unlike other marine mammals, they are herbivorous. The vast majority of a sirenian's diet consists of sea grass and most of the rest is other aquatic plants. All species have been known to supplement their diet with invertebrates, mostly during times of poor food availability. When feeding, they move their snouts through the sediment, letting sensory bristles detect plants. They then use their flexible and muscular lips to pull up the sea grass, roots and all. While an individual can eat up to 15% of their body weight a day, they are known to seek out seagrass patches with higher nitrogen content instead of eating everything they can get. This reliance on seagrass limits the range of sirenians to shallow coastal areas, rivers, and estuaries in warm climates. Hearing and touch (with the bristles that cover their bodies) are their main senses. Their eyes are weak, making them almost blind. Sirenians are large, with the largest ever known, Stellar's sea cow, growing up to 10 meters (33 ft) and 11 tons. Mature sirenians are large enough to have no natural predators. Like all marine mammals not named sea otters, sirenians have a thick layer of blubber to keep them warm. Their bones are extremely dense and likely act as ballast to counteract the buoyancy of the blubber. In the marine mammal breath-holding competition, sirenians do pretty bad. They can hold their breath for about 15 minutes at max.

(image: a dugong. It is similar in appearance to a manatee, but skinnier. Its tail is a fluke with two points. Its head is larger and the snout and mouth point downwards)

Sirenian reproduction is somewhat poorly-understood. They only have a single calf at a time (with a gestation period of about a year) and mothers will raise them for one to two years. Calves mature quickly, reaching sexual maturity in around 2-5 years in manatees and 8 years in dugongs, though most females do not give birth until between 6 and 15 years. Their nipples are located behind the flippers, making a nursing calf appear to be sucking its mother's armpit. Sirenians are solitary animals who typically only congregate in groups when females are in estrus. Males are believed to compete for the right to mate and may engage in lekking. Lekking is when a male will claim a territory and mate with females in this territory while chasing opposing males out. Sirenians live long lives, with the oldest known individual being a female dugong that lived to 73. Despite how long they live, each female will only get pregnant a few times in her life.

(image: a manatee mother with calf. The calf looks like a smaller version of the mother and is suckling, making it appear to be biting the mother's armpit)

As with all marine mammals, sirenians are descended from land mammals. The study of sirenian evolution has led to a surprising conclusion: the closest relatives of sirenians are elephants. It sounds weird, but there is substantial DNA evidence supporting this conclusion. In addition, the tusks of a dugong (see below) and flexible and prehensile lips of sirenians are based on the same structures as the tusks and trunks of elephants. It gets better, the next closest relative of both groups are the hyraxes, who look more like rodents than anything that should be related to an elephant or a manatee. All three are part of a clade called paenungulata, which is part of a clade called afrotheria. The other main group within afrotheria is afroinsectiphilia, which consists of aardvarks and various shrews. The afrotherian family reunions must be wild.

(image: a scientific diagram showing a cladogram of afrotheria and the groups within it. source)

The dugong (Dugong dugon) is the last surviving member of its family, which also included the now extinct giant Stellar's sea cow. The easiest way to tell a dugong apart from a manatee is its tail, which is shaped like a dolphin's fluke instead of the round tails of manatees. Internally, there are also multiple differences, many of them relating to the skull. The skull has a very distinct shape, with the upper jaw bending down at a sharp angle. The tip of the upper jaw has two short tusks emerging from it. These tusks are found in moth males and females, but develop differently. In males, they emerge when the calf reaches sexual maturity, while those of females only emerge later in life and sometimes not at all. It is believed that these tusks are used by males to fight over females, as males are often found with scars matching the shape of the tusks. Dugong teeth as simpler than those of manatees, being simple pegs. While manatee teeth will be replaced continuously through life, dugongs only get one set and have to make it count. Dugongs reach an average length of 3 m (10 ft) and 420 kg (930 lbs). Dugongs have the largest range of any sirenian, stretching from east Africa to the Solomon islands east of Australia. This range is fragmented rather than continuous and dugongs are separated into multiple isolated populations. The largest population is believed to exist in northern Australia.

(image: a dugong feeding on seagrass, seen from the front. It's snout is being dragged through the sediment, leaving a cloud of dirt behind it. Small yellow fish surround it)

The west Indian manatee (Trichechus manatus) does not live in west India. It lives in North America. I dunno who named it, but you had one job. The species is divided into two subspecies: the Florida manatee (T. m. latriostris) found in the Gulf of Mexico and east coast of the United States, and the Antillean manatee (T. m. manatus) found in the Caribbean and down south to Brazil. The Antillean subspecies is much more poorly known compared to the Florida subspecies. The Florida manatee may be the most well-studied of all manatees due to the extensive conservation efforts regarding them since the 1970s. Like other manatees, the WI manatee has a round, paddle-like tail and fingernails on its flippers. Their diaphragms are divided into two hemidiaphragms, each of which contracts one lung. They have the northernmost territory of all manatees, which comes with some consequences. They are susceptible to stress and even death when exposed to water under 20 degrees C (68 F). They travel south during winter, usually to southern Florida, but conservationists still have to rehabilitate manatees harmed by cool water every year.

(image: tourists in transparent kayaks observing a west Indian manatee swim below them)

The Amazonian manatee (Trichechus inunguis) is the only sirenian that lives entirely in freshwater, residing in the Amazon river basin. They move seasonally inhabiting flooded areas during the wet season and lakes during the dry season. They fast during the dry season, subsisting off of their fat stores. There are believed to be multiple relatively isolated populations of Amazonian manatee, but studying them is difficult due to them preferring to live in areas away from humans. The Amazonian manatee is the smallest sirenian, reaching between 160 and 230 cm (5 ft 4 in to 7 ft 7 in) and 120 to 270 kg (265 to 595 lbs). Scientist Marc van Roosmalen has proposed the existence of a related species, the dwarf manatee, that lives only in one tributary of Aripuanã river, which is in the habitat range of the Amazonian manatee. Their existence is debated, but most manatee scientists think that they are misidentified juvenile Amazonian manatees.

(image: an Amazonian manatee with calf, seen from ahead and below. they have the same body plan as the above images, but are a darker grey with a white patch on the stomach)

The African manatee (Trichechus senegalensis) is the only species found in the old world, in west Africa from Senegal to Angola. They occupy the largest range of habitats of all sirenians, from tropical islands to flooded forests, to offshore sand flats, to lakes and rivers. They will swim up river during the wet season and back down during dry season. Some isolated populations live exclusively in rivers, never venturing out to sea. They are the most omnivorous of the sirenians, seeking out invertebrates to eat and stealing fish from nets. Many cultural groups in their range consider the African manatee sacred, some saying they used to be people and that killing one requires paying a penance. Mami Wata, a water spirit revered in throughout west, central, and south Africa, has been identified with manatees by some folklorists.

(image: an African manatee seen from the side in an aquarium. It looks almost identical to the west Indian manatee)

All sirenians are classified as vulnerable by the IUCN, except for the Antillean manatee, which is endangered. As they have few to no predators as adults, the primary threats for all sirenians come from humans. Boat strikes and getting tangled in nets kills and injures many individuals, possibly more than die of natural causes. This is not helped by them lacking fear responses to predators, meaning they don't flee from humans and boats. All species were historically hunted for their meat, blubber, and bones, reducing their populations. While all species are now legally protected, poaching and legal hunting by indigenous groups still occurs. They are also threatened by habitat loss as coastal development, pollution, and climate change reduces the range of seagrass. Damming has also reduced their ability to travel up rivers, cutting off valuable feeding ground. Learning about freshwater ecology will make you despise dams. In the United States, the west Indian manatee has become an icon of conservation, especially in Florida, where they have extensive legal protections. Controversially, the US government reduced their legal protections in 2017, much to the ire of many conservation groups. The manatee is the state marine mammal of Florida, presumably narrowly beating out dolphins and meth heads wandering around the everglades.

(image: two juvenile manatees who were abandoned by their mothers. They are being bottle fed by employees of the Cincinnati zoo. Ideally, they will be able to be released into the wild once weaned)

[ocean-sunfish-hater]

Hi,

I saw your post about barrel bugs and I wanted to ask if you know more interesting marine parasites?

(Personally I think that dendrogasters are quite cool)

Dendrogasters are pretty cool! I don't know much about them but they look really... odd.

ID: a picture of Dendrogaster showing its unsual body plan, with its branching structures that end in spherical growths. It is light yellow to orange in colour. It is set against a black background and part of a ruler can be seen.

There's a whole host (haha) of interesting marine parasites, and I won't go through all of them now but here's a few that you might like.

Rhizocephala are a parasitic group of barnacles that live on crabs. They have no internal organs except gonads, a few muscles and the remnants of a nervous system. In fact, their only distinguishable bodyy structure is the female reproductive organs, which sit outside of its host's body. Here's a really cool drawing of the filaments which it sends out into its host's body to absorb nutrients directly from their blood:

ID: a black and white drawing of a crab infected with the parasite Rhizocephala. It shows the underside of the crab with the externa (female gonads) visible and a network of filaments that the parasite has grown throughout the host body.

I'm sure you've heard of tongue lice, so I won't labour the point too much, but spark notes is that they attach to the gill arches or tongue of a fish, then cut off the circulation to the tongue so that it withers off. It then replaces the fish's tongue.

ID: an image of a tongue eating louse inside a fish's mouth. The louse is pale, almost white in colour and has two black eyes. The fish is like :O

Finally, this isn't a marine parasite but you'll see why I include it in a second, but the tongue worms (not to be confused with the tongue eating louse). They are actually terrestrial and mostly infect the respiratory tracts of vertebrates (sometimes, though very rarely, us). What I find interesting is that they have no circulatory, excretory or respiratory organs and rely soley on the host to do all these things. Isn't that cool?

ID: a drawing of a tongue worm (Pentastomida). It has a segmented body that ends in a point. At the other end there are 4 stubby limb-like structures.

If you're still reading , you might be wondering why I picked these ones and why the tongue worm is awkwardly shoved in there? Because @chowaniec I have tricked you; this is not a post about marine parasites, it's a post about the diversity of crustaceans. THAT'S RIGHT, ALL OF THESE ANIMALS, WITH THEIR WEIRD LIFE CYCLES AND UNCRUSTACEANY BODIES ARE COUSINS OF CRABS AND SHRIMP AND LOBSTERS. AND THAT INCLUDES YOUR ORIGINAL SUBMISSION OF DENDROGASTER, WHICH IS WHAT GAVE ME THIS IDEA IN THE FIRST PLACE.

All of these lil guys just have highly specialised bodies that have lost many of the features we associate with crustaceans so that they can be better parasites. It's really only though careful analysis of their lifecycles and genetics that we can even determine them to be crustaceans at all.

I wanted to showcase the immense diversity of crustaceans and the weird and wonderful flexiblity of evolution. I also wanted to show you why morphological criteria for classification fall short, even beyond the "coconuts are mammals" meme.

Thanks for the submission, and thanks for being patient with me! I know this one took a little while longer to receive but I hope it was worth it.

[quotesfrommyreading]

Often, moonlight—independent of the tides—signals the start of a species-wide reproductive marathon. By syncing these orgies to particular phases of the moon—one of nature’s most prominent and reliable records of time—animals increase their chances of finding a mate and overwhelm opportunistic predators with their sheer numbers.

During certain phases of the moon, Sesarma crabs in Japan collectively scuttle across mountain slopes toward sea-flowing rivers, where they release their eggs and sperm. The annual migrations of Christmas Island crabs, which move in waves of crimson from forest to sea to mate and lay their eggs, also seems to be linked to moonlight’s shifting intensity. Moonlight even sharpens the visual acuity of horseshoe crabs, which come ashore on certain nights to mate. Likewise, studies suggest that the moon’s glow is one of the environmental triggers for synchronous spawning in tropical rabbit fish. Moonlight likely increases production of the hormone gonadotropin in these fish, which promotes gamete maturation.

 —   The Lunar Sea

[orcinus-veterinarius]

I don’t mean this to be snarky (just trying to learn more) but do you have a source for saying that preventing cetaceans/orcas from breeding in captivity harms their welfare? my thought was that allowing breeding would improve it but not allowing it wouldn’t decrease it, bc they can have other forms of enrichment.

Thank u 😊

Thank you for asking! Here's a few informal sources from current cetacean experts.

This quote is from Dr. Isabella Clegg, a PhD scientist specializing in dolphin behavior and welfare. She runs an organization that provides third party welfare checks to zoos, aquariums, and sanctuaries. It's also worth noting that she is neither explicity pro- nor anti-captivity.

"Reproduction is the most natural and fundamental life event for dolphins, and all animals, which means it is likely to be good for their welfare. The key factor that enhances welfare is the presence of young dolphins in the group, and for 3 main reasons. The presence of young cetaceans has been shown to 1) increase positive social behaviour in adults, 2) provide close social bonds for females, which they would not otherwise experience, and 3) reduce male coercive behaviour towards females with young. All of these factors would lead to improved welfare at the group level, and if breeding was banned, welfare would likely be reduced for the affected groups." (x)(x)

Below, you'll find an interview with Dr. Holley Muraco, the current Director of Research at the Mississippi Aquarium, speaking on the importance of reproductive behavior to the welfare of managed dolphins during her time at Dolphin Quest (a company founded and still owned by marine mammal veterinarians). Dr. Muraco's PhD is in dolphin reproductive physiology.

I hope you find this helpful!

[fishenjoyer1]

Fish of the Day

Today's fish of the day is the atolla jellyfish!

The atolla jellyfish, also known as the coronate medusa, alarm jellyfish, and deep-sea jellyfish, scientific name Atolla wyvillei, is a crown jellyfish (from the order Coronate) found in deeper waters. (Note: Atolla jellyfish may refer to several species of atolla, but  Atolla wyvillei is the most commonly found globally.) The atolla jelly is one of the most commonly found jelly in the depths, living in the midnight zone (1,00 to 4,000 meters below the surface) across the globe! Although, they can be found as high up as 300 meters below the surface, we still know little about them due to their depth range.

Most well known about these jellies is their bioluminescent response to predation. When this jellyfish is threatened or disturbed, a blue-green bioluminescence lights up, lighting up the predator. The visual is that of several rings flowing down the bell of the jelly, I would recommend looking up a video, it's quite stunning! This confuses the predator, shocking it into halting its attack, and giving off the illusion of multiple jellyfish in the area. However, this lightshow also acts as a calling for larger predators, lured in by the lights, the attacker of the jellyfish is far better prey to larger animals. Allowing the atolla jelly time to retreat. In the early 2010's this was used by marine biologist Edith Widdler to invent the E Jelly, a device which mimics the luminescent patterns of the atolla. The E Jelly has since been successful in luring animals, and its use provided us with the first ever video of a live giant squid in 2019.

The atolla feeds on crustaceans and shrimp, along with floating nutrients around them. The jellyfish has 20 marginal tentacles and a trailing tentacle, which is larger and thought to be used in catching prey. Reproduction can be done both asexually, and sexually, using the trailing tentacle to pull themselves towards a mate and attach temporarily. They grow between 20-180 mm (about an inch to 7 inches) in diameter along the bell, and although tentacle length is currently unknown, it is estimated to be 10 inches at most.

Have a wonderful day, everyone!

[sonicasura]

Biological Complications of Being A Kaiju

Here we are with my personal thoughts on the possible biological changes done to Kaiju No. 8's Kafka Hibino. I will be talking about different biology such as reproductive amongst others things. Fair warning that shit will get weird. (Nothing is sacred with kaiju.) Now let's get started.

Kafka's kaiju form has traits seen from various different animals mainly reptiles and sharks. His hide acts closer to that of the Nurse Shark with some traits of marine iguanas alongside poisonous frogs. Thanks to this, he can secrete substances like poison or liquid waste from his entire body. (Kafka doesn't fully know this because otherwise the man would never use his nips like THAT again.)

Similar to Marine Iguanas, his kaiju side is an very adept swimmer. Kafka's average speed can be clocked around 80mph in water but he could go even faster by manifesting a tail and webbing his hands/feet. The awkward shape of his neck conceals special gils that filters out water or harmful gases.

Kafka is cold blooded to a degree. He prefers seeking out warmth by sunbathing but it'll take constant extreme cold to make him hibernate. Attempts to force him into such a state will result in his kaiju side growing thick fur similar to polar bears as a defense mechanism. This coat being shed off over the course of Spring and regrown during the fall.

Kafka's body will adapt under extremely stressful situations. These particular changes can be difficult to near impossible for him to will away as they were done by Tiny(Mosquito Kaiju). Pecking order involving alterations to their kaiju form: Tiny, Kafka, Ai.

Fangs are very similar to that of any shark. Should Kafka lose any then new ones normally grow in after two minutes. His jaw strengthens matches that of an alligator mixed with a snapping turtle. Unless Kafka lets go then breaking his teeth is the only way to free oneself. Although the fangs will be embedded in his victim as a way to cripple them.

Kafka has a tendency to shed his scales from time to time. A normal process as its a way for his body to naturally dispose of the dead ones. Losing large patches occurs from either sickness or bi-annual molting.

Similar to a lizard, Kafka can climb and hang on different surfaces. His claws are perfect to retain his grip should the climbing target be slippery or someone tries to pull him off. If push comes to shove, one adaptation Kafka can use is camouflage similar to a chameleon.

*Reproductive Section is here. You can skip this as nothing new is past it.*

Reproductive organs are still present even in kaiju form. Similar to a lizard, Kafka's genitals are hidden behind a cloaca for protection. His kaiju form comes with both sets of reproductive organs i.e male and female.

The species are highly adaptive when it comes to keeping their population numbers stable. Kafka wasn't exactly happy to learn about this change. Especially since most kaiju are the egg laying type, his included.

Should conception occur then at least 3-5 eggs are laid after 3 weeks. During that time period, Kafka will eat twice his body weight and be quite aggressive around unfamiliar faces. A nest is also made from various bedding materials like pillows, blankets, to even mattresses.

Eggs will hatch in the span of 4-7 weeks. Newborn hatchlings are the size of kittens and have small fangs as they only feed on meat or fish at this age. They age at the same rate humans do thus reach full maturity in around 20 years. All of them will have a human form and obtain it at the 4-5 year mark.

Similar to a possum, Kafka will carry any whelp he has on his back. His instincts make it difficult for him to leave them alone for too long until they are at least 3 months old. It'll take some heavy persuasion from anyone close to Kafka to have someone babysit for him during that time period.

Experimenting with Kaiju biology is quite the acid trip, huh?

[animalshowdown]

Phylum Round 2

Annelida: Segmented Worms. This group includes earthworms, leeches, and many classes under the umbrella of "polychaete". This diverse phylum encompasses deposit feeders (eating dirt), detritivores, scavengers, deadly ambush predators, filter feeders, parasites, herbivores, and more. They are broadly defined by their repeating body segments and parapodia, which are nubby appendages used for both movement and breathing. Some have curved jaws for catching prey or scraping detritus off of rocks, while others have wide, elaborate feather-like fans for filter feeding. While able to crawl freely, a majority of marine Annelids spend most of their time in self-built tubes or burrows. Among their many important functions, they play a key role in mixing soil/sediment, breaking down decaying organic matter, and providing a key food source to countless other animals.

Cycliophora: An incredibly specialized phylum, the Cycliophorans consist of a single genus. These animals live exclusively on the mouthparts of lobsters. Yes, all Cycliophorans. This is considered a commensal relationship, as the lobster is not harmed by the Cycliophorans' presence. This phylum has an interesting reproductive strategy involving cloned dwarf versions of the male, embryos that drain all nutrients from the mother, and larvae that must be strong swimmers to hopefully re-colonize the host lobster's new exoskeleton whenever it molts.

[bestanimal]

Round 1 - Phylum Echinodermata

(Sources - 1, 2, 3, 4)

Echinodermata is a phylum of animals which are bilaterally symmetrical as larvae but radially symmetrical as adults. It includes starfish, brittle stars, sea urchins, sand dollars, sea cucumbers, and sea lilies.

Echinodermata is the largest marine-only phylum, and echinoderms can be found at every ocean depth from the intertidal zone to the abyssal zone. They make up a large portion of life in the deep sea. They are diverse, with some being sessile (lacking self-locomotion) while others are motile (able to move independently). Many are restricted to crawling slowly across the sea floor, while some can swim through the water column. They have a skeleton beneath their outer layer of skin, which is composed of calcite-based plates called ossicles. This would be heavy if it was solid, so it is instead porous. The ossicles may be fused together or articulated, and may have external projections such as warts or spikes. Echinoderms are often brightly-colored, and some of their pigment cells may even be light-sensitive, causing many echinoderms to change appearance completely as night falls. Their diet varies, with some species being predators, some being filter-feeders, some being herbivores, some only eating algae, and some being detritivores. Some injest food through a mouth and expell waste through an anus, while others can only expell waste back through their mouth. The ventral side of many echinoderms is covered in tube feet, each of which typically end in a suction cup pad. They primarily use their tube feet for movement, though some sea urchins will also “walk” with their spines.

Almost all species have males and females, though some are hermaphroditic and at least one reproduces by parthenogenesis. Eggs and sperm are released into open water, where they are fertilized externally. Some species may aggregate during reproductive season to increase the likelihood of fertilization. A small handful of species have internal fertilization. Some echinoderms, especially in colder areas, brood and carry their eggs until they hatch. Echinoderm larvae are usually planktonic, swim via cilia, and have bilateral symmetry. During metamorphosis, the left side of their body grows at the expense of the right side, which is eventually absorbed, ending with the body arranged in five parts around a central axis. Some species reproduce asexually. They do this by splitting in two, like a cell, and generating a new body half from the old one. Some larvae may also reproduce by budding.

The first echinoderms appeared in the Early Cambrian.

Propaganda under the cut:

Echinoderms are able to regenerate tissue, limbs, organs, and sometimes full bodies from a remaining portion of limb. Starfish and brittle stars may detach an arm as a defense mechanism, swimming away while a predator is distracted by the wiggling limb. Some sea cucumbers, on the other hand, take this to the extreme by expelling their cuvierian tubules (respiratory tubes) to entangle potential predators. Sometimes this is also accompanied by a discharge of toxic holothurin. It can take 1.5 - 5 weeks for the tubules to regenerate, depending on species.

The hard endoskeletons of dead echinoderms are geologicallly important, contributing to limestone formations.

Echinoderms sequester about 0.1 gigatonnes of carbon dioxide per year as calcium carbonate, making them important contributors in the global carbon cycle.

Sea stars are heavily muscled, and are able to go from soft to rigid in order to pull open the shells of their mollusc prey.

Sea urchins are among the main herbivores in reefs and there is usually a fine balance between the urchins and the kelp and other algae on which they graze. In the past, mass mortalities of sea urchins have led to algae blooms.

Some sea cucumbers have webbed swimming structures that allow them to swim freely through the water column. Pelagothuria natatrix (seen below) is the only truly pelagic echinoderm known so far.

(source)

Echinoderms seem to have an innate internal clock. Even at the depths of the ocean where no light penetrates, they are still able to synchronize their reproductive activity.

We don’t know much about Sea Pigs (Scotoplanes globosa) (seen in gif) other than that they’re poisonous sea cucumbers that feed on detritus at the sea floor. But we do know that they are often seen clutching young king crabs (Neolithodes diomedea) and carrying them around. One possible theory is that these crabs latch onto S. globosa to gain access to nutrients and movement, and sheltering beneath the poisonous sea pig allows them to hide from predators. As sea pigs are sometimes plagued with parasites that bore holes into their bodies, the crabs may also help the sea pigs by keeping them clean of parasites. For now, all possibilities are just hypotheses, but we can stil Awww at the globby pink sea cucumbers cuddling their little pet crabs.

Along with Hemichordata, they are the closest relatives of Chordata (aka our phylum!)

Some sea urchins pick up rocks, shells, and other debris and carry them around to shade themselves from the sun. Some people who keep them as pets have come up with creative ways to allow them to do this without dismantling the architecture:

(source)

Silly hats aside, these seemingly simple animals are using tools.

[smaller-comfort]

So how do you imagine snail love darts and necrontyr working/combining? Cause I am interested~

Aksjdhsk ahahaha oh god okay here we go

(Tumblr crashed on me three times while I tried to write this, but I will not let that stop me from rambling at length about snail sex, speculative xenobiology, and various ways that necrontyr get to be fucked up little guys.)

Okay. Some assumptions/general thoughts: necrontyr do not have "dual-use" reproductive/waste elimination systems (inferred from Trazyn's hilarious disgust at the idea, but honestly it would be entirely believable for him to have completely lost any and all memories of necrontyr biology). Most higher order animals do (they're efficient!), but you start to see ones that don't when you get down to bugs and marine creatures, so that's what kicked off this train of thought.

I'm assuming also there is relatively little sexual dimorphism among necrontyr (not for any particular reason, although my understanding is that actual female necrons are a relatively new thing in wh40k lore, so that fits). And finally, everyone constantly dying of turbo cancer has led to a 'throw everything but the kitchen sink at it' evolutionary approach to reproductive strategies.

Okay, now snails: they use the darts during courtship to deliver hormones that increase the likelihood of fertilizing their partner's eggs; after the several-hours-long mating dance, they'll exchange spermatophores. (Fun fact, the penis, copulatory canal, and dart sac are all located inside the genital pore, on the snail's head. Mating dances can involve a lot of biting.) Snails have bad aim, but it's not uncommon for both snails to end up getting stabbed during courtship.

"Copulatory canal" is a deeply unsexy phrase, btw. So are most words we use when talking about sex, unfortunately. *sigh*

Anyway. While many necrontyr do only have one set of functional reproductive organs by the time they reach adulthood (either because the other set was always vestigial or because it gets removed to reduce the spread of cancer), both sets are usually present in some fashion. Sterility would be fairly common, but medical technology is able to mitigate some of that; the lower classes, at least, need to be able to breed like rabbits to feed the war machine. Gender is mostly divorced from reproductive role by the time biotransference happens; in addition to male and female, there would have been at least one other normative gender, possibly two (to account for both null and multimodal genders). Gender fluidity would have been common and largely unremarkable for necrontyr. (It's still largely unremarkable for necrons, but it's not particularly common; they're mostly fixed with whatever gender they had at biotransference.)

Okay, so, love darts. Pretty much only ever used by nobles/the military, because in the upper classes of society, sex isn't about reproduction, it's about reinforcing social hierarchies. And necrontyr social hierarchies tend to be inherently about violence in one way or another. Sexual dominance is generally more about who gets stabbed with the dart than it is about which penis is going where. (That's still a factor, but it's secondary, since genital configurations/functionality can be a bit of a wildcard.) Snails take an egalitarian approach to sex; necrontyr categorically do not. Both parties consenting to be darted would be considered weird and perverted.

Kind of going off ancient greek/roman sexual mores here; it would be entirely unthinkable, for example, for Obyron to be the penetrative partner in either sense with Zahndrekh. (Then again, Zahndrekh is a shameless pervert.) Sex between two social equals is generally accompanied by an agreement- sometimes tacit, sometimes explicit- about not using the darts. Doing so would be an overt act of aggression. Often, to prevent any potential misunderstandings, they'll voluntarily empty their dart sacs ahead of time.

Forcing someone to empty their dart sac prior to sex is a pretty common form of sexual humiliation. When done voluntarily, it's a sign of submission or respect. (Darts usually have a refractory period of a few days, depending on the person's overall health. Single-chambered dart sacs are typical, but multiples aren't unheard of. Leads to occasional 'surprise! You thought I was submitting to you but now you're getting fucked instead' situations.)

The dart sac would be located in their mouths, under the tongue; it's meant to be ejected into the soft tissue of the mouth, but it's sharp enough to pierce the skin anywhere. (This does mean kissing can be Complicated, or at least somewhat subversive, depending on everyone's social standing.) Normally it gets broken down and absorbed by the recipient's body; pulling one out tends to be extremely uncomfortable/painful.

The exact cocktail of hormones and neurochemicals it injects the other person with would vary somewhat between individuals, but can potentially vary widely between dynasties or social classes due to genetic/geographic/cultural differences. Some might include a mild paralytic agent; some sort of euphoric effect is also common. (This is all in addition to the original function, which, uh. Is to make the recipient more likely to get pregnant.) The shape of the dart varies in a similar fashion, ranging from a straight, smooth bone spike to something more elaborate with barbs or fluting.

(A bloody mouth can signify a lot of things to necrontyr- in addition to violence or illness, it's also inherently erotic. Necrons who remember this try very, very hard not to think about it when confronted with Flayed Ones.)

(Yenekh: *very sexily smearing his mouth with blood and draping himself all over Oltyx*

Oltyx: *oblivious, can't stop thinking about how pretty Yenekh is*

The rest of the flayed ones: *still not sure why their king and his consort haven't fucked nasty in a pile of carrion yet. Maybe they need a bigger pile of carrion? Yes, that's probably it. They will take care of this for their beloved king.*)

Crypteks have their own social hierarchies within their conclaves, but they're usually not as concerned with sexual politics as nobles and the military tend to be. Most people believe that crypteks all lace their love darts with poison, and the crypteks don't try to discourage that assumption. Some of them probably do, tbh.

Necrons, of course, don't have genitalia, but they can still stab each other with love dart analogues- this ranges from things like executive buffer override packages sent via interstitial channel, to actually physically jamming a spike of necrodermis into a neural input node. (From a purely aesthetic/romantic standpoint I also like the idea of love darts constructed out of crystallized core flux. The first time Zahndrekh does that to Obyron he goes into complete cascade failure and takes several hours to reboot.)

If Orikan and Trazyn did have sex pre-biotransference, one of them would have darted the other without permission (probably accidentally, being that they are both intensely nerdy losers and thus Bad At Sex by necrontyr standards), setting off a sixty-five million year hate-sex feud that neither of them can even remember the origin of. Orikan would've gone after Trazyn's mouth with a pair of pliers at some point; joke's on him, Trazyn's into that.

(Trazyn does have a collection of necrontyr love darts in the archives- all of them ones he collected personally when he was alive. He has no absolutely no memory of slutting it up back in the day, though, and probably doesn't even realize what they are. Sannet, unfortunately, does remember, and wishes he didn't. He has had to put up with so, so much over the years.)