#Hexanchiformes

[jammerspyjammass]

You may not know this but im a huge fucking nerd

My favourite shark from each order:D ignore how goofy they are

[moon-snailsss]

I got to see a very close relative of my favorite shark; the Bluntnose Six-Gill. I saw the Broadnose sevegill!! Seeing one was so exciting!! They are literally prehistoric babies :3 A fun fact about the Broadnose sevengill is that they’re the only extant member of the genus Notorynchus. Notorynchus is a genus of deep water sharks.

Another fun fact is that I am the #1 fan of all Hexanchiformes

[sharkest-sharks]

*grabby hands* give me sharkie facts

most sharks have two dorsal fins, but not all!! such as

order Hexanchiformes, with 6 species: frilled sharks (2), sixgill sharks (2), and sevengill sharks (2)

in order Carcharhiniformes: one fin catshark! Pentanchus profundicolus

[taxonomytournament]

Taxonomy Tournament: Cartilaginous Fish

Hexanchiformes. This order of sharks are the most primitive morphologically. It includes the cow shark.

Squatiniformes. This order is made up of the angelsharks, which have flattened bodies and broad pectoral fins, and are bottom-dwelling ambush predators

[unofficial-sean]

[shark-a-day]

Todays shark is...

The Sixgill Sawshark!

Fun Fact: Outside of the Hexanchiformes order, it is the only shark to have more than 5 gill slits!

[fishenjoyer1]

Fish of the day

Today's fish of the day is the Frilled shark!

The frilled shark, scientific name Chlamydoselachus anguineus, is known for its irregular teeth. This animal is often referred to as serpent-esc due to the unique swimming motions, and living in the darkened sea floor, where they can camouflage. Found at depths of 120-1,280 meters of depth (394-4,200 feet) the distribution of these animals is referred to as "spotty" and despite knowing of them since the 1870's, we are unsure of their full range. However, we have found all current populations in the Indo-Pacific, Pacific, and Atlantic oceans. 

Notable populations can be found along the Pacific coastline along California, Chile, Japan, and Southern Australia and New Zealand. Notable Atlantic populations are along the coast of Brazil, outside Southern Canada, Florida, the Western Sahara, and The West coast of Europe. They live along the edges of the continental shelf, spacing itself from both coastlines and the surface. Like other deep sea sharks, the frilled shark takes place in diel migration, which is a migration that takes place nightly when deep sea animals travel toward the surface when it is dark to prey on surface animals.

Considered as one of the older and more primitive sharks, this 6 gilled wonder has fossils that were found dating as far back as 95 million years ago, making them living fossils. Related to the Greenland sharks, scaffold sharks, and silk sharks they are a member of the Hexanchiformes order, what was once thought to be the basal group for sharks, but it actually just a particularly old order within the Squalomoprpha subdivision. The Hexanchiformes order is known for having no nictating membranes, a further back spiracle than most sharks, and notable to our focus today, lacking the multi layer enameloid layer on the tops of teeth.  

Before we had found many of the specimen that named them living fossils, the frilled shark specifically was thought of as old due to their only partial cartilaginous notochord, which is a kind of elastic rod-like structure found in bilateral animals. Notochord can be found is all embryonic vertebrates, but is replaced by the bony vertebral column, with the original notochord being found in the intervertebral discs. The mouth of the frilled shark contains 300 needle-teeth which has a cusp and two cusplets (a raised surface, and then two divots outside of it, making smaller raised surfaces) which have anywhere from 19-29 rows on the top and bottom. The mouth is known for being able to open wide and eat foods that are larger then their entire body, similar to other deep sea fish, but being the only shark to do so.

The diet of the shark is primarily made up of cephalopods, but will eat gastropods, fish, and small sharks when available. It hunts for these with mechanoreceptor hair cells, which sense movement and vibration, and pressure in the water nearby them. The frilled shark is a ambush predator, often preying on tired or dying prey that have finished spawning, hiding along the sea floor, waiting to strike by biting. These teeth are used for snagging animals and hooking into the flesh so regardless of struggle, and the frilled sharks relatively weak bite, they cannot be freed.

Frilled sharks have defined breeding season, but they do have a size at which they reach sexual maturity. At around 1-1.2 meters male frilled sharks will mature, and at around 1.3-1.5 the female sharks will do the same. The shark is ovoviviparous, meaning that they are an egg, but that this egg will hatch within the mother and the pup will then sustain off of this yolk until live birth, and the shark will have as many as 2-15 pups after their gestation of 3-3.5 years. The pups are then left to fend for themselves, and will reach a full adult size of 2 meters, and pass away anywhere from 20-25 years after birth.

Have a wonderful day, everybody!

[shark-of-tha-day]

shark of the day: onefin catshark, pentanchus profundicolus ------------------------------------------------------------ the onefin catshark is a small species of deep water catshark named for its singular dorsal fin, a trait usually only seen in hexanchiformes. they grow to be around 50 cm(~1.3 ft) in length. onefin catsharks are found around the phillipines in deep water. they likely feed on small deep water fish and invertebrates.

[sad-trash-pigeon]

sharks are an elasmobranch fish, a subclass of cartilaginous fish. there are eight orders, or families, of sharks that are categorized by their biology !!

shark orders within elasmobranchii:

classifications;

heterodontiformes(bullhead or horn sharks) - five gill slits, a dorsal fin with a strong spine and flat and sharp teeth in their mouth. an example of this is horn sharks.

orectolobiformes(carpetshark) - five gill slits, 2 spineless dorsal fins, an anal fin and spiracles(paired openings which take in water and ventilate the gills) near their eyes. an example of this is whale sharks.

lamniformes(mackrel sharks) - five gill slits, a large mouth with several rows of teeth, two dorsal fins, and anal fin and the ability to maintain a higher body temperature than the water around them. an example of this is great white sharks.

carcharhiniformes(ground sharks) - five gill slits, moveable eyelids which protect their eyes from injuries, two spineless dorsal fins, an anal fin and a large mouth with sharp teeth located behind their eyes. an example of this is hammerhead sharks.

squaliformes(dogfish sharks)- found in nearly every marine habitat, they have long snouts and a short mouth, five gill slits, two fins, and no anal fin. an example of this is spiny dogfish.

hexanchiformes(primitive sharks) - six or seven gill slits, one dorsal fin, an anal fin, thorny teeth and most live in deep cold water. an example of this is frilled sharks.

pristiophoriformes(sawsharks) - long snouts similar to saws, five or six gill slits, two dorsal fins, no anal fin, wide pectoral fins, transverse teeth and most of them live in tropical waters. an example of this is longnose sawsharks.

squatiniformes(angel sharks) - flattened bodies, a mouth with dermal flaps in front of a short snout, nasal barbels, eyes and a spiracle on the top of their head and no anal fin. an example of this is angel sharks.

*if any information is incorrect please tell me! i will correct it on here and on my research document :)

@tearsonthepage

[precambrianhottopic]

pro tip if you have a favorite shark look up what order it's from :)) also put your favorite shark in the tags if you want :))

[sharkwithc4]

Sharks

Temporal range: Early Jurassic – Present

Clockwise from top left: spiny dogfish, Australian angelshark, whale shark, great white shark, horn shark, frilled shark, scalloped hammerhead and Japanese sawshark representing the orders Squaliformes, Squatiniformes, Orectolobiformes, Lamniformes, Heterodontiformes, Hexanchiformes, Carcharhiniformes and Pristiophoriformes respectively.

Scientific classification Edit this classification

Domain: Eukaryota

Kingdom: Animalia

Phylum: Chordata

Class: Chondrichthyes

Infraclass: Euselachii

Clade: Neoselachii

Subdivision: Selachimorpha

Orders

Galeomorphii

Carcharhiniformes

Heterodontiformes

Orectolobiformes

Lamniformes

Squalomorphii

Hexanchiformes

Pristiophoriformes

Squaliformes

Squatiniformes

Synonyms

Pleurotremata

Selachii

Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha (or Selachii) and are the sister group to the Batoidea (rays and kin). Some sources extend the term "shark" as an informal category including extinct members of Chondrichthyes (cartilaginous fish) with a shark-like morphology, such as hybodonts. Shark-like chondrichthyans such as Cladoselache and Doliodus first appeared in the Devonian Period (419–359 million years), though some fossilized chondrichthyan-like scales are as old as the Late Ordovician (458–444 million years ago). The oldest modern sharks (selachimorphs) are known from the Early Jurassic, about 200 million years ago.[citation needed]

Sharks range in size from the small dwarf lanternshark (Etmopterus perryi), a deep sea species that is only 17 centimetres (6.7 in) in length, to the whale shark (Rhincodon typus), the largest fish in the world, which reaches approximately 12 metres (40 ft) in length. They are found in all seas and are common to depths up to 2,000 metres (6,600 ft). They generally do not live in freshwater, although there are a few known exceptions, such as the bull shark and the river shark, which can be found in both seawater and freshwater. Sharks have a covering of dermal denticles that protects their skin from damage and parasites in addition to improving their fluid dynamics. They have numerous sets of replaceable teeth.

Several species are apex predators, which are organisms that are at the top of their food chain. Select examples include the tiger shark, blue shark, great white shark, mako shark, thresher shark, and hammerhead shark.

Sharks are caught by humans for shark meat or shark fin soup. Many shark populations are threatened by human activities. Since 1970, shark populations have been reduced by 71%, mostly from overfishing. Sharks are spread across 512 described and 23 undescribed species in eight orders. The families and genera within the orders are listed in alphabetical order.

I LOVE YOU THANK YOU /P

[iwannabeasixgillshark]

There is something sweet and special when someone shares with another what they love. There is potency there that exists in no other form of emotion. You don't even need to fully understand to appreciate the adoration one holds for any number of subjects. It shines through like a fire behind stained glass; coloring your world with their light. And even when they're done talking, one would be forgiven for being dazzled, for you have seen passion in the flesh and felt its warm caress. It is more precious than any diamond and more nourishing than the finest foods. It transcends description; it is neither scientific, nor spiritual. It is the most human ability we possess: to love.

What do you love about sixgill sharks?

Honestly, at first I just really loved their silly little faces. I was just starting to really do research on sharks (which is a topic I’d wanted to learn abt for years at that point) and I found hexanchiforms, which I thought was super cool just cause they were so unique. And then I think I saw a video of a sixgill, and I was just like WOW they’re big but also they look so baby?? I was obsessed with their big eyes and the fact that they always have this goofy little smile on. And honestly, I don’t think I’ve ever seen a video clip of a sixgill that didn’t end with it ramming it’s face into a completely avoidable obstacle. I love them.

There’s just something that is really satisfying to me about the way thwyre shaped and they move. All of the adaptions they’ve taken on to live in the deep sea is so fascinating, and also the fact that they’re still really close to prehistoric sharks and they’ve barely evolved in millions of years?? That’s fucking insane, I can’t even imagine being so perfectly adapted to an environment you don’t change and don’t move for hundreds of thousands of years.

I watched this documentary on them a while back too which is really good (I’ll link it if can find it) abt the sixgill population in Seattle, and all the research done on them too. Sharks have such interesting social lives that I feel like are really undocumented, and sixgills especially dont have a whole lot of easily accessible information on them. I’d love to study them sometime — and if not study, at least dive with them. They’re so majestic (but also so silly and goofy at the same time) and I just. Hmgnenghgm. They’re just so cool to me

[moon-snailsss]

Bluntnose Six-Gill shark

Felt like I should finally make a post about my favorite shark species (They are my everything)

Basics

Bluntnose Six-Gill sharks are the largest species in their order(Hexanchiformes), with males reaching lengths of 12 feet and females reaching lengths of 18 feet! Belonging to the cow shark family (Hexanchidae), this species has remained relatively unchanged since the early Jurassic period. Their name reflects their distinctive anatomy (extra gill slits) :3

Physical characteristics

The Bluntnose Six-Gill sharks have many distinctive features, such as their streamlined, elongated body, a blunt snout, and a small dorsal fin positioned towards the back of its body. It has grayish-brown skin that helps it blend into its dark surroundings, while a pale belly provides camouflage from below (Countershading). Many people don’t think that Bluntnose sharks have dorsal fins, but that’s untrue! Unlike most sharks, they only have one dorsal fin, however it’s located more posteriorly compared to others. This adaptation is common in bottom-dwelling species as they don’t require the same level of speed as pelagic species! With a dorsal fin that’s positioned closer to the caudal fin, it enables them to make sharper turns and increases maneuverability.

Respiratory features/evolution

As we’ve previously noted, Bluntnose sharks have six gills, but why? The additional gill slit allows the Bluntnose shark to extract oxygen from the water more efficiently, which is a crucial adaptation in deep-sea environments where oxygen is scarce. Older species from the cow shark family have persistently remained unchanged, and continue to find success with a more primitive body.

Habitat

Bluntnose Six-Gill sharks are found all over the world on continental shelves, slopes, abyssal plains, seamounts, and mid ocean ridges. They reside in deep, cold waters between 200-1000 meters in temperate climates, but can be found in shallower waters in cooler climates. Scientists have primarily studied their behavior in shallower waters in high latitudes, but less is known about their behavior in deeper waters.

Migration

Bluntnose Six-Gill sharks exhibit diel vertical migration, which means they migrate vertically through the water column during the day and night. They stay in deeper depths around 600 meters during the day, and then move to shallower depths of around 200 meters during the night. Diel vertical migration isn’t uncommon among smaller marine organisms such as zooplankton, fish and squid. They travel deeper during the daytime to avoid predators, and migrate back to shallower depths at night to feed. Scientists are unsure why Bluntnose sharks exhibit this behavior, BUT I think it’s because they track the abundance of migrating prey items, as they feed on most of the smaller organisms I listed.

Diet

Bluntnose sharks feed on fish, squid, rays crustaceans, and agnathans (hagfish and sea lampreys). They also scavenge carrion and participate in feeding frenzies.

Reproduction

Bluntnose sharks reproduce through ovoviviparity. This means that the eggs hatch inside the female, where embryos develop until they’re ready to be born. Scientists believe their gestation periods last longer than two years. Litter sizes range from 20-110 pups, however it suggest that mortality rates for the pups may be high. Each pup is around 70 cm at birth.

Conservation status

The Bluntnose shark is listed as near threatened on the IUCN list. Its popularity as a sport fish makes it vulnerable to exploitation.

That’s pretty much it :3 all of this is why, you too should love the Bluntnose-Six gill shark 🦈

[sharkest-sharks]

Info dump to me about the sharkies I WANT TO KNOW 1. Most aggressive sharkie 2. Fastest Sharkie 3. Strangest sharkie 4. Oldest Sharkie 5. Smallest Sharkie 6. Biggest Sharkie 7. Slowest Sharkie 8. Cutest Sharkie 9. "Ugliest" Sharkie

heheheh i know all of this from the top of my head 🦈 🦈 🦈 🦈 🦈 🦈 🦈 🦈 🦈

Bull sharks! they're the most aggresive towards humans along with great whites and tiger shark

Shortfin makos!!!

This is more subjective and i'd say goblin sharks, frilled sharks and cookie cutter are probably some of the weirdest ones. Honorable mention: the helicoprion (extinct friend but he was so strange <33)

Okay so the shark that can grow the oldest is the greenland shark, they can reach more than 400 years old The oldest *species* is the frilled shark! Along with the rest of the hexanchiformes order (this are sixgill and sevengill sharks)

Dwarf lantern shark! he's just a leetol guy

Whale shark! it's also the biggest fish in general followed by the basking shark

Greenland sharks, they're just vibing in the water

Subjective again, small sharks definetly get to me. Spotted catsharks, zebra pups, and nurse sharks too

In general people will probably say goblin? I think they're really weird and that's the thing i like the most about creatures so <3

[justanotherinterneruser]

good evening !!

i finally found your tumblr (im not a stalker i promise) and i just wanted to pop over and say hi!!! i love your works more than life itself and i hope you know how appreciated you are :3

anyway if you could be any sea creature what would you be and why i would be one of those long squids that live in the bottom of the ocean because they're creepy and weird and funny looking (affectionately)

GOOOOOOOOOOOOOOOOOOOOSEBERRY!!

HULLO!!! Good to see ya!!! Thank you so much for saying hi and saying such nice things because I may or may not be snuggled in bed a little weepy over your words 😭❤️. I am so glad you enjoy my silly little drivels of nonsense

If I was to be a sea creature I would want to be a Hexanchiformes because they are some WACK lil guys or I’d be a Greenland Shark because they are round funky dudes

[unofficial-sean]

Bluntnose Sixgill Shark Fact Sheet!

It’s about time I made one of these, considering all the time I’ve put into researching them. I still have. . . 30 more papers to read out of 64, so I will update this post as I learn more.

> The taxonomic name of the bluntnose sixgill shark is Hexanchus griseus. It is under the family Hexanchidae, which are known as the “cow sharks.”

> Sixgills are globally distributed on continental slopes, shelves, and sea mounts, except for the Arctic and Southern oceans.

> Sixgills are ovoviviparous, which means their young develop in egg sacks within the mother’s uterus. They give birth to up to 108 pups and are polyandrous, which means one litter was multiple contributing fathers.

> Sixgill pups start out with a total length of 68-73cm, and can grow up to 5m!

> Sixgills occupy deep waters during the day and shallower waters at night, migrating up and down the sea floor slopes at dusk and dawn.

> A group of sixgills is called a shoal. The largest recorded gathering of sixgills was a shoal of 21 sharks.

> Sixgills share a genus with two other species, the Atlantic sixgill shark (Hexanchus vitulus) and the bigeye sixgill shark (Hexanchus nakamurai)

> Hexanchid teeth have been found as far back as the Eocene epoch, about 33.5 to 56 million years ago.

> Sixgills growing up in Puget Sound have friends! They can often be found in pairs with same-sex conspecifics.

> Sixgills are generalist scavengers that spend most of their time above the sea floor (epibenthic).

> These sharks occupy depths up to 2500m.

> Sixgills give birth about once every two years.

> Sixgills are docile sharks, and have never harmed a human.

> Males have “scrolls” which sheath the claspers, making sexing at a glance more difficult than with other sharks species.

> We have yet to develop a method of determining the age of these sharks due to poor skeletal calcification. We don’t know how old they are or how long they live.

> Sixgills have comb-like teeth on the lower-jaw which allow them to saw and shear off chunks of flesh from bodies.

> A sixgill shark was responsible for biting a submarine fiber optic cable on a certain clip recorded by a commercial ROV in 2003!

> A sixgill shark once gave a ride to a crab on her fin! Her name is Crusty.