feelingautistic

A marine biologist on Tumblr? I mainly like to focus on the wonderful world of sharks but all marine life is fascinating so who knows where we will go?

[feelingautistic]

Why does this fish has such a big head?

So this is a flowerhorn cichlid and these aren't actually wild fish but the product of artifical selection by humans, meaning other cichlid species have been selectively bred to produce hybrids with these large heads and bright colourations (a process similar to dog breeding). Cichlids are a particularly significant group of fish in artificial selection because of their ability to rapidly develop new species over only a few generations.

In these cichlids, the large heads (formally known as nuchal humps) are believed to have a function in mate attraction, perhaps as a prominent display of bright colours.

However, it's more likely flowerhorn cichlids developed such large heads because we designed them that way for aesthetic purposes or perhaps for its unique appearance.

[feelingautistic]

While researching xylophagy in animals for my previous post, I discovered this genus of catfish Panaque, some of the only xylophagous vertebrates. Their jaws are adapted to consuming wood, having spoon-shaped teeth and highly angled jaws to chisel and scrape chunks off wood. Scientists have also discovered symbiotic gut bacteria that can aid in digesting wood.

However, it is debated whether these catfish are truly xylophagous as they don't seem to gain much energy from wood or hold wood particles in their gut for very long. Instead, some believe these catfish consume wood to feed on detritus (dead organic matter) found living within or on the surface.

[feelingautistic]

Types of Animal Diets (Part 1)

Most of us will be familiar with categorising animals into carnivores ('meat eater'), herbivores ('plant eater') or omnivores ('all eater') based on their diets but many animals have developed more specialised diets. This could be due to the availability of the food type in their environment and/or adaptations the animal has developed to handle and process the food type. While the list of all specialised animal diets would be too expansive for one post, I've selected some of the more interesting or unique ones to present to you:

Sanguivores: Animals that feed on blood (the behaviour of drinking blood is referred to as hematophagy) -> These animals have evolved feeding appendages for piercing skin and sucking blood, saliva with blood thinners and a tolerance for high levels of iron and heme as is often found in blood. Examples of sanguivores include the infamous mosquitoes and leeches, lampreys and vampire bats.

Osteophages: Animals that feed on bones -> The primary reason suggested for why some animals eat bones is because they are a rich source of phosphates which is lacking in herbivorous diets. Bearded vultures are the only known obligate osteophage with diets made up of up to 90% bone which they either swallow whole or drop from great heights to break apart (leading to their common name ossifrage meaning 'bone-breaker').

Lepidophages: Animals that feed on (fish) scales -> These animals have developed a variety of methods of extracting scales from fish including ramming into prey or tearing off scales from passing fish. Lepidophagy often comes with limited energy profit due to the high energy demand of extracting scales but fish scales are abundant and regenerated if lost so can be a valuable food source in food-limited environements. Examples of lepidophages include wimple piranhas and a few species of cichlids.

Xylophages: Animals that feed on wood -> These animals often house symbiotic microorganisms in their digestive system which can break down the tough cellulose in wood. These animals often exist in conflict with humans, breaking down wooden structures such as furniture and wooden ships. Examples of xylophages include termites, shipworms and wood-boring beetles.

[feelingautistic]

Believe it or not, this is what cownose ray teeth look like. They're shaped like tiles because cownose rays primarily feed on hard-shelled organisms and so evolved strong jaws and teeth as powerful as concrete designed for powerful crushing.

[feelingautistic]

Rays vs Skates

As shark enthusiasts, you are likely vaguely familiar with the Chondrichthyes class of animals (or 'cartilagenous fish' in plain English, grouped for their bones made of cartilage) but, of course, we cannot forget about the sharks' relatives: the famous rays and their less famous relative skates. However, as members of the same superorder Batoidea, they appear far more similar to each other than to most sharks (perhaps besides the flatter shark groups). While some ray groups such as the eagle or manta rays can be easily identified, stingrays in particular can appear very similar to skates as shown below:

(Before you keep reading, which is the ray and which is the skate?)

So how can we tell stingrays and skates apart?

One of the biggest differences between the two is the iconic stinging barb of stingrays, found midway across their tail, which skates lack. Instead, most skates opt for thorn-like scales along their back for defense from predators.

On the topic of tails, stingrays tend to have longer, thinner tails while skates tend to have shorter, thicker tails.

Another useful distinction between the two is stingrays tend to be diamond-shaped (often appearing round) while skates are more triangular.

Another distinction which is perhaps less useful for spotting one in the water is that rays give birth to live young while skates lay 'mermaid's purses' eggs like some shark species.

(Oh and just to trip you up further, sometimes we give skates, like the one pictured above, names like 'thornback ray', just to really confuse people)

[kropotkindersurprise]

you know how it is

[mbari-blog]

#tfw a flatfish totally invades your space bubble 🤨

Flatfishes spend most of their time lying on their sides, camouflaged against the muddy seafloor or buried in the sand. When it’s time to find a meal or to escape an unwelcome predator, they swiftly push off the bottom and gracefully undulate their flattened bodies to swim, employing elongated fins for extra propulsion.

These remarkable fishes are found in all ocean basins. Some live in shallow waters, while others thrive at depths of more than 1,500 meters (about 4,900 feet).

[feelingautistic]

Eagle rays are characterised by their long noses that are designed like shovels to dig through sand on the seafloor and dislodge prey hiding in the ground. As relatives of sharks, eagle rays also possess ampullae of Lorenzini, electroreceptors that allow them to pick up the electrical impulses produced by prey hidden in the sand.

[feelingautistic]

Where are the ears on a basking shark? All the diagrams I can find either aren’t covering that or are of a great white.

Unlike us mammals, the ears of most marine animals, including sharks, have no external structure so it can be difficult to see the ears of a basking shark because an outside view would show nothing more than a hole. Honestly, it took me a while to locate what I think is their ears in photos but see the image below for my best guess:

(As you can see, it's nothing exciting. Just a very inconspicuous hole)

[feelingautistic]

Unlike other lantern shark species, the viper lantern shark's jaws are designed to grasp food and swallow it whole rather than cut off chunks of flesh. Viper lantern sharks can eat fish over 30% as long as itself.

[feelingautistic]

If you've ever watched a video of a shark chomping on its next meal, you might have noticed the jaw seems to unhinge from its mouth a little to wrap around prey.

This is because, unlike most animals, their jaws are not fused to their skulls but instead connected to the skull by flexible cartilage that can stretch forwards, giving sharks extra range and better grip of food.

For an extreme case that clearly demonstrates this extra range and better grip, may I present the goblin shark:

[feelingautistic]

thoughts/facts on the dwarf lanternshark?

The dwarf lantern shark is part of the lantern shark group that get their name from the photophores on their belly that emit light. Dwarf lantern sharks use this light in shallow waters to blend in with sunlight shining on the water.

[feelingautistic]

Pyjama sharks get their name from their stripy pyjama-like appearance that breaks up their outline among kelp and shadows.

[feelingautistic]

The primary method of determining if a shark is a male or a female is by looking for the claspers (pictured above), an extension of the pelvic fins that is only found on male sharks.

[feelingautistic]

(Tumblr wasn't very happy with me showing you shark genitals so I'll leave off any photos of shark sex - I guess Google it?)

If the topic of shark claspers has you wondering what the claspers are for, they are in fact used in reproduction. Unlike most fish that reproduce externally by releasing sperm and eggs into the water, sharks have internal fertilisation and shark mating is actually quite a violent process.

The claspers get their name because that's sort of what they do: clasp onto the female through insertion into the cloaca and deliver sperm to the female. However, this process is quite violent as navigating internal fertilisation underwater is quite challenging and the male shark will bite the female in order to cling on while they manoeuvr into a position to mate.

[feelingautistic]

The primary method of determining if a shark is a male or a female is by looking for the claspers (pictured above), an extension of the pelvic fins that is only found on male sharks.

[c-53]

I have a bisexual guppy and its funny as hell to watch because it seems like he’s only bi out of desperation. Like all of the female guppies are unimpressed by him, and dont accept his mating displays, and every time he fails, he goes over to a SPECIFIC male guppy (the prettiest male guppy in the tank) like PLEASE PLEASE PLEASE PLEASE and that male guppy always lets him????

[domnika-deactivated20250923]

i would read that fanfic ngl

[c-53]

About my fish??

[graceful-not]

HELP?????

[everyfandom-girl]

YEAH THIS IS SCIENTIFICALLY RECORDED

WOMEN LOVE GAYBOY

[feelingautistic]

goodmorning sharkman. it is i. back for more posts on my favorite animals. can I get something on eels. any and all subspecies work.

good morning jester, it is i eelman?

One area of research that's always interested me is when two species work together or otherwise mutually benefit each other and moray eels are a great example of such cooperation between species.

Moray eels and groupers (this large predatory fish pictured in the photo above) share such a partnership, working together in order to hunt food. On paper, they seem to make a very strange duo. Groupers are daytime predators that hunt in open water while moray eels are nocturnal predators that hunt within coral and other small crevices.

However, it is in fact these differences that make their partnership so effective. Prey respond to groupers by slipping into small crevices the fish can't follow while prey respond to eels by swimming into open water where eels are less effective swimmers...you may already be able to guess how the two hunt together.

Groupers have been seen signalling at eels when it's time to hunt and the two species will even scope out potential prey together. Groupers can drive prey into crevices where the eels lie in wait and groupers can also lead eels to prey hiding in crevices where the eel can slip in and drive the prey out...right into the jaws of the groupers. This hunting partnership has much greater success than their individual hunting strategies and doesn't requiring learning any new behaviours or hunting strategies, making it a cheap but greatly beneficial relationship for both of them.

Reference: Bshary, R., Hohner, A., Ait-el-Djoudi, K., Fricke, H. (2006) 'Interspecific Communication and Coordinated Hunting between Groupers and Giant Moray Eels in the Red Sea.', PLOS Biology, 4(12). DOI: https://doi.org/10.1371/journal.pbio.0040431