#dogfish sharks

[just-here-for-shark-stuff]

Daily Shark Fact - 4/24/2025

Today's shark is the spiny dogfish shark!

The basics: the spiny dogfish (Squalus acanthias) is one of the most common and best-known species of dogfish sharks. Like other dogfish sharks, they're known to hunt in packs - some packs of spiny dogfish sharks have been observed to include thousands of individuals! They are found worldwide in coastal temperate and subarctic waters.

Conservation status: vulnerable. The spiny dogfish is one of the most common shark species in the world, but they are also one of the most at risk of extremely frequent bycatch from coastal fishing nets and trawlers. Some populations of spiny dogfish around Europe have declined by as much as 95%. They also have perhaps the longest gestational period of any vertebrate (estimated 1.5-2 years long!), which doesn't help! Despite this, they are still very common sharks, and population recovery is in progress in many places thanks to fishing regulations.

Today's fun fact: spiny dogfish get their name from the spines on each dorsal fin - if threatened, they will arch to try and stick predators with them. The spines produce a mild venom!

[jesse-is-spiralling]

Dogfish?

ooh yes

there are 119 (i think?) different species of dogfish sharks!

they r just little guys and they steal bait which makes them an absolute nuisance to fishermen (fond)

they have venomous spines that can cause a lot of pain (good on them)

good sharks 9/10

send me an ask with a species of shark and i will rate/review them

[sharkfactoftheday]

A viper dogfish’s fins are small, translucent, and very thin.

[just-here-for-shark-stuff]

Daily Shark Fact - 3/30/2025

Today I'm talking about cookiecutter sharks!

The basics: cookiecutter sharks (Isistius brasiliensis) are best known by their feeding strategy, which revolves around neatly biting cookie-shaped pieces out of prey much larger than themselves (these are small sharks, topping out at less than two feet long!). They are Squaliformes (members of the large order of dogfish sharks), and like many other species in their order, they migrate up and down the water column, moving upward at dusk and descending to deep oceanic waters during the day. Though they have been known to take the occasional chomp out of deep-water swimmers, cookiecutter sharks are rare for humans to encounter and are not classified as dangerous to humans.

Conservation status: least concern

Today's fun fact: though many people know about the cookiecutter shark's famous eating habits, not as many people know that, like many other small deep-water Squaliformes, cookiecutter sharks are bioluminescent! The luminescent photophores on their bellies disrupt their silhouette when seen from below, and the dark collar-shaped pattern around their neck might act as a lure by mimicking the shape of a smaller fish swimming by, luring bigger prey by for the shark to feed on!

[just-here-for-shark-stuff]

Daily Shark Fact - 4/7/2025

Today's shark is the viper dogfish!

The basics: the viper dogfish shark (Trigonognathus kabeyai) is a rare species of deepwater dogfish shark. Rarely encountered by humans except as extremely incidental bycatch of deepwater trawl lines, they are very small (under 2 feet long) sharks that mostly eat bony fishes. Like many other deepwater dogfish sharks, the viper dogfish has bioluminescent photophores along its belly, and though we don't know for sure thanks to its rarity, we know from related dogfish species that it might migrate up and down the water column, preferring very deep waters during the day and moving upwards (but still staying deep) at night.

Conservation status: least concern. Though the species is naturally rare and more research needs to be done, viper dogfishes have no commercial value and are rarely threatened by bycatch.

Today's fun fact: uniquely among dogfish sharks, viper dogfishes have evolved to swallow relatively large prey whole! Most dogfish sharks have jaws and teeth specialized for biting and tearing off chunks, but viper dogfishes have teeth specialized for grasping and holding on. They don't have a muslce in their jaws that most other dogfish sharks have that ordinarily controls pulling the jaws back in after biting - instead, one of the bones in their jaw is set up to swing their jaws down and forward, allowing them to shoot out their jaws to quickly grab prey! Viper dogfish sharks can swallow prey almost 40% of their own size.

[just-here-for-shark-stuff]

Daily Shark Fact - 5/23/2025

Today's shark is the velvet belly lanternshark!

The basics: one of the most abundant deep-sea sharks, the velvet belly lanternshark (Etmopterus spinax) is a small species of dogfish shark (no more than 18 inches long) named for their black, velvety-looking bellies. Like other lanternsharks, they have bioluminescent photophores along their bellies, which provide counter-shading that helps camouflage the shark from predators. It can be identified by its very small gill slits. Velvet belly lanternsharks have very large livers, over 15% of their body mass on average, with a high quantity of liver oil that makes them neutrally buoyant in the water - unlike most sharks, which are negatively buoyant and will sink, velvet belly lanternsharks will not.

Conservation status: vulnerable. This shark has virtually no commercial value, but is a very frequent bycatch in deep-sea trawl lines. They reproduce slowly, and populations are very vulnerable to decline from over-fishing.

Today's fun fact: the deep sea has a higher concentration of heavy metals than higher up in the water column. To combat this, velvet belly lanternsharks' t-cells, a type of white blood cell, are able to identify and mark heavy metals in their blood stream so they can be passed out of their bodies.

[sharkfactoftheday]

Five of the seven genera of kitefin sharks only contain one species. 

[sharkfactoftheday]

Are dogfish dangerous and do they go near the coast? I know they're native to the Irish sea and I plan to swim on the beach there soon

Unfortunately “dogfish” is used colloquially to describe a lot of sharks. It may be used to refer to the entirety of the order Squaliformes, or it could refer to a subset of that order, generally sleeper sharks or members of the family Squalidae. Many species of catshark are also referred to as dogfish as well.

Based on some googling I’m guessing the sharks you’re thinking of are probably catsharks (the small-spotted catshark, aka sandy dogfish, in particular seems to be very common around Ireland), which are relatively harmless. As long as you leave them alone they shouldn’t bother you. They live on continental shelves, which are by the coast, but likely deeper than you will encounter.

So I don’t think you have much to worry about beyond general caution wrt The Ocean.