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Today on Animal Fact Files we’re talking about snailfish. Thank you to reflex arc for today’s request!

Snailfish kind of look like oversized tadpoles. They can reach two feet (61 centimeters) in length and are considered the deepest living fish - as in, researchers haven’t found a fish that lives deeper in the ocean than these guys. Supposedly, the pressure where some snailfish species live is so intense it would feel like the weight of more than 3,000 rhinos pressing against you. In other words, you would be crushed. But not the snailfish. Snailfish are found from the Arctic to Antarctic waters. They occur most diversely in the Pacific ocean but also appear in the Atlantic and India oceans. Though snailfish live at depths of four and a half miles (7,240 meters) below the ocean’s surface, some species are also found in tide pool areas - though… the tidepool living snailfish probably don’t visit their abyssal relatives for the holidays... and vice versa!

It’s believed there are hundreds of snailfish species, with plenty more than haven’t been named. Snailfish don’t have scales, but they do have long dorsal fins that reach back to their tails, and they often come equipped with a sucker. In shallow water species especially, snailfish use this sucker to hold fast to the bottom or even hitch a ride on roving crabs to their next meal. Snailfish use crabs for other more heinous reasons, but we’ll get back to that in a bit. These fish spend most of their time at the bottom of the water column. For shallow water species, currents may push them along, so these suckers come in handy for staying in place; however, the deeper a snailfish species lives, the less likely it is to have developed this suction cup-like apparatus, and the deepest dwelling species may not have a sucker at all!

While perusing the ocean floor, snailfish seek out prey in the form of worms, crustaceans, cephalopods, and gastropods. Strangely enough, these fish may also commonly be called “sea snails”, however, this common name seems even more confusing than snailfish, so we’ll just stick with that. Of course, in the instances of both common names it feels worth it to say these animals aren’t... snails.

Snailfish in turn are eaten by fish such as cods, skates, seals, and seafairing birds including auks, though deep water species have been cited as the top predators of their habitats. It makes sense. I mean, have you ever heard of a skate living more than four miles below the ocean’s surface? As a diverse group of fish, the breeding habits of snailfish species can differ. Deep sea species have been documented to lay small clutches of eggs throughout the year while shallow water species lay eggs in large clutches. This is where the crabs come back into play. In areas where snailfish and king crabs coexist, the snailfish lay their eggs in king crab gills. How they do it is still a mystery, but why seems pretty obvious - protection. The female specifically seeks out a king crab that has recently molted and lays at least one clutch of more than 800 eggs in the king crab’s gills. Here the eggs are protected and aerated in the gill chamber until they hatch. Unfortunately for the crabs, the relationship seems mostly parasitic, because the eggs often harm the crab’s gills and no benefit for the crabs carrying the eggs has been found. Other species are less diabolical and lay their eggs in substrate and protect them, y’know like normal fish...

Though this doesn’t apply to all snailfish species, deep water snailfish species specifically don’t respond to light; AND their skeletons have developed to adapt to the pressure in their abyssal underwater environments. Not only do deep sea snailfish have flexible skeletons made partially of cartilage, they literally have holes in their skulls to compensate for the pressure at the bottom of the ocean.

For more facts on snailfish, check out the links in the description. Give a thumbs up if you learned something new today, and thank you for watching Animal Fact Files.