Unless you're a deep-sea fisherman, you probably won't ever see the world's most common fish- perhaps even the most common vertebrate! Members of the family Gonostomatidae, better known as bristlemouths, are tiny fish that spend most of the day swimming at or below depths of 500 m (1640 ft); they only come up to the surface at night to feed on plankton and small fish with their unusually large mouths. There are only 32 identified species, but scientists estimate their the sum of their populations make up trillions to quadrillions of fish!
(Image: A species of bristlemouth fish (Gonostomatidae sp.) by Sonke Johnsen)
Anya is live and ready to show you everything. Watch her strip, dance, and perform exclusive shows just for you. Interact in real-time and make your fantasies come true.
âś“ Live Streamingâś“ Interactive Chatâś“ Private Showsâś“ HD Qualityâś“ Free Actions
Free to watch • No registration required • HD streaming
Anatomy: very diverse morphology between families; adapted for the deep sea; most have large mouths extending back past the eyes; all have teeth on the premaxilla and maxilla; teeth are often transparent and non-reflective; some have a chin barbel (“whisker”); some have delicate cycloid scales which are easily sloughed off; some are scaleless; the dorsal and/or pectoral fins are missing in some, but others have an adipose fin; some are bioluminescent
Diet: plankton, small crustaceans, small fish
Habitat: in oceans worldwide; most stay in deep waters during the day, but follow the migration of plankton towards the surface at night, swimming back to deeper water when the sun rises; some larger Stomiiformes stay in the deep sea 24/7 and feed on the smaller migrating fish as they return
Evolved in: Late Cretaceous
Do you have a favorite in Stomiiformes?
One or more of my favorite animals is in Stomiiformes
I love at least one or more of these animals
I like at least one or more of these animals
I am neutral about all of these animals
I dislike all of these animals
Voting ended onJul 8, 2025
Propaganda under the cut:
The bristlemouth family, Gonostomatidae, is relatively small, but they make up for their low diversity in numbers. The genus Cyclothone (with 13 species) (image 4) is thought to be one of the most abundant vertebrate genera in the world, numbering into the quadrillions!
Bristlemouths are protandrous: they begin their lives as males and some of them switch to female. Male bristlemouths are smaller than females.
Some bristlemouths rely on their bioluminescence to find prey while others use it to avoid predation. However, the most common way that their bioluminescence is used is for communication between fish.
The smallest species of this order is the bristlemouth Cyclothone pygmaea. Native to the Mediterranean Sea, it reaches just 1.5Â cm (0.6Â in) as an adult.
Dragonfish (family Stomiidae) have a hinge to their neurocranium and upper-jaw system, allowing them to open their jaw more 100 degrees! This allows them to consume extremely large prey, often 50% greater than their standard length.
Like anglerfish, dragonfish use a barbel as a lure, though their barbel extends off of their bottom jaw. The tip of the barbel is bioluminescent, which attracts prey such as bristlemouths and lanternfish, who use light to communicate. The color, shape, and size of the barbel varies between species, which also allows for same-species recognition.
Dragonfish also have a light-emitting photophore beneath their eyes. In most species, this light is blue, but in some it is red. The scale-less Goldleaf Dragonfish (Chirostomias pliopterus) was the first life form discovered able to emit a red light (the second being a siphonophore of the genus Erenna). Later, more dragonfish genera (Aristostomias, Malacosteus and Pachystomias) were also found to emit red light from the photophore under their eyes. It is hypothesized that red light may be used for intraspecific communication, as well as to illuminate prey, as many organisms in the deep sea can only see blue light.
Viperfish (genus Chauliodus) (gif above) have large, fang-like teeth that are so long that they would pierce their own brain if they were misaligned.
The largest stomiiforme is the Obese Dragonfish (Opostomias micripnus), which measures about 50Â cm (20Â in) in adult length.
The BBC’s “The Voyage of the Dawn Treader” 1989 special modeled its sea dragon off of a dragonfish, basing it off of the description in C.S. Lewis’ book. I watched that sea dragon scene over and over as a kid and it forever impacted my approach to creature design. You don’t need a giant, unrelenting centipede snake when deep sea fish are RIGHT THERE. It was just a Creature migrating up from the depths at night to look for food, and when the food put up too much of a fight, it gave up, like any animal would.
Tetraodontiformes. This order contains many fishses with unusual body structures, such as boxfishes, which are boxy as the implies, pufferfishes, which are round and able to inflate, and the ocean sunfish, the largest bony fish.
Stomiiformes. This order is made up of deep-sea fishes. It includes dragonfishes, loosejaws, viperfishes, and bristlemouths, the most populated family of vertebrates, with population numbering in the hundreds of trillions to quadrillions.
For the final entry in this series, let's take a look at a modern weird-headed species – and where better to find some of the strangest and most unique-looking animals alive today than the deep sea?
Malacosteus, also known as the stoplight loosejaw, is a 25cm long (10") genus of dragonfish found at depths of over 500m (1640') in oceans all around the world, with the exception of the Mediterranean and polar waters. Two different species are currently recognized, with Malacosteus niger here known from just below the Arctic Circle down to the southern reaches of the subtropics, and Malacosteus australis ranging from there to around 45°S, and up towards the equator in the Indian Ocean.
And there's a lot to unpack here with the anatomy of this one.
First of all, there's the fact that its entire head can hinge away from its body, gaping enormous jaws with long fang-like teeth.
The bottom of its lower jaw has no skin membrane connecting the two sides, attached to the rest of its bizarre head only by the hinges and a single exposed muscle, reducing water resistance so it can shoot its trap-jaws out extra fast to snare prey.
From Kenaley, C. P. (2012). Exploring feeding behaviour in deep-sea dragonfishes (Teleostei: Stomiidae): jaw biomechanics and functional significance of a loosejaw. Biological Journal of the Linnean Society, 106(1), 224-240. doi.org/10.1111/j.1095-8312.2012.01854.x
Once it catches something it retracts its head, and several sets of pharyngeal teeth further back grab hold of its prey and direct it down its throat.
(Let me remind you that this isn't an early April Fools joke. This thing is completely real.)
In addition to all that anatomical weirdness, it's also one of the only deep-sea fish that can both see and produce red-colored light. Most creatures living at that depth have lost the ability to see red since that frequency doesn't penetrate so far down through water, but the stoplight loosejaw has evolved to take advantage of that by using bioluminescent red light as its own personal night vision goggles.
Using large red photophores under each eye, it can shine a spotlight out ahead of itself and see other deep-sea animals all clearly lit up, while remaining completely invisible to both them and any nearby larger predators. It's able to perceive the color red thanks to a pigment in its eyes modified from chlorophyll, a visual setup unique to this fish and not known from any other vertebrate.
It also has a smaller green photophore further down on its head – inspiring its common name thanks to the resemblance to traffic lights – and many smaller blue and white ones over its head and body.
So, with its highly specialized jaws and ability to see things other deep-sea animals can't, the stoplight loosejaw must be hunting something pretty impressive, right?
And as it turns out, it eats… plankton.
The vast majority of its diet appears to be copepods, small zooplanktoic crustaceans that are incredibly common in the waters the loosejaw inhabits. It may simply be "snacking" on such a convenient food source in-between rare encounters with larger prey – but it may also be getting the chlorophyll-based pigment needed for its night vision from eating them.
Anya is live and ready to show you everything. Watch her strip, dance, and perform exclusive shows just for you. Interact in real-time and make your fantasies come true.
âś“ Live Streamingâś“ Interactive Chatâś“ Private Showsâś“ HD Qualityâś“ Free Actions
Free to watch • No registration required • HD streaming
Lampriformes. This order is made up of opahs (also known as moonfish or sunfish) and their relatives, such as oarfish, crestfishes, and ribbonfishes
Stomiiformes. This order is made up of deep-sea fishes. It includes dragonfishes, loosejaws, viperfishes, and bristlemouths, the most populated family of vertebrates, with population numbering in the hundreds of trillions to quadrillions.
Stomiiformes. This order is made up of deep-sea fishes. It includes dragonfishes, loosejaws, viperfishes, and bristlemouths, the most populated family of vertebrates, with population numbering in the hundreds of trillions to quadrillions.
Aulopiformes. This order is made up of lizardfishes, many of which are deep-sea. Some are hermaphroditic with the ability to self-fertilise.
