La Jolla

Invertebrate exhibit— Natural History Museum, Los Angeles.

Shoutout to deep sea cephalopods

gotta be one of my favorite genders

Tumblr should appreciate Two Crabs by Vincent Van Gogh more

It's two crabs, whats not to love

Mooseblood

Drew some poisonous & venomous sea creatures for my first foray into risograph printing. I’m so pleased with how bright the colors turned out in-person. :') [shop link]

nudibranchs via seaslugs_n_stargazers on ig

If you asked me as a kid what my favorite animal was, there's a good chance I'd respond "chambered nautilus", though I probably would mispronounce it. I don't know if it's still my favorite but it's definitely up there in the pantheon of weird critters. For this Wet Beast Wednesday, I'll discuss my childhood favorite.

(image: a nautilus)

The nautilus is a cephalopod that lives in a curved shell and looks similar to (but is not closely related to) the extinct ammonites. There are 6 living species in two genera, but 90% of the time when someone is discussing nautiluses they are referring to the most well-known species: Nautilus pompilius or the chambered nautilus. Nautiloids are ancient, going back to at least the late triassic with their more primitive ancestors going back as far as the ordovician period, a time when only invertebrates and primitive plants occupied the land and true fish had not yet appeared. Because of their ancient history, nautiluses are sometimes considered living fossils. I have ranted before on how misleading the term "living fossil" is so I'll spare you that for now. Nautiloids are considered a sister group to the celoids, which contains all the squid, octopus, cuttlefish, and everything else we thinks of as cephalopods. Nautiluses should not be confused with paper nautiluses. Also called argonauts, paper nautiluses are a group of octopi that make an egg case which looks like a shell.

(image: a nautilus)

The most noticeable feature of a nautilus is its shell. The shell is smooth and finely curving, naturally growing in the shape of a logarithmic spiral (though not, as is commonly stated, a golden ratio spiral). The shell has a stripy outer layer and an inner layer coated with nacre. Internally, the shell is divided into camarae (chambers) separated from each other by walls called septa. Each septum has a small hole in it through which a strand of tissue called the siphuncle passes. Most of the nautilus's body is in the foremost and largest chamber. The shell grows new septa as the animal grows, with the nautilus's body moving to a new chamber as it becomes too large for previous ones. Juveniles are typically born with 4 septa, with adults having as many as 30. In addition to providing protection from predators, the shell is also key for regulating buoyancy. The septa can contain pressurized gas or water and the siphuncle regulates their contents by either adding or removing water to increase or decrease buoyancy. Because of its pressurized contents, the shell can only withstand pressure at depths up to 800 M (2,400 ft) before imploding. Oddly enough, nautiluses can be safely brought up from deep waters where most animals would be killed by the pressure changes. To move, the nautilus pulls water into the first chamber of the shell using its hyponome (siphon) and shoots it back out. The chambered nautilus is the largest species, with a maximum shell diameter of 25 cm (10 in), though most get no larger than 20 cm (8 in).

(image: a diagram of nautilus anatomy. source)

Where celoid cephalopods have tentacles, nautiluses instead have numerous cirri. Unlike tentacles, cirri are less muscular, are not elastic, and have no suckers. They are used to grab objects using their ridged surfaces and can hold in so hard that trying to take an object away from a nautilus can rip off its cirri, which will remain firmly attached. In addition, the nautilus has modified cirri that serve as olfactory receptors and a pair that serve to open and close the shell when the nautilus needs to retract into it or emerge. Nestled within the cirri is the beak, which is used to consume the nautilus's primary prey of invertebrates, though they have also been seen scavenging fish. Their eyes are less developed than most cephalopods, lacking a lens and consisting of a small pinhole that only allows the nautilus to see simple imagery. Their brains are differently structured than most cephalopods and studies have found them to have considerably shorter long-term memories.

(image: a chambered nautilus (upper left) next to a rare Allonautilus scrobiculatus. source)

Cephalopod reproduction is quite different than that of other cephalopods. While most cephalopods are short-lived and semelparous (reproducing only once), nautiluses can live over 20 years and reproduce multiple times (iteroparity). They do not reach sexual maturity until around 15 years old, with females laying eggs once per year. Eggs are attached to rocks and take 8 to 12 months to hatch. Males have a structure called the spadix composed of 4 fused cirri that they use to transfer sperm to females. Females lose their gonads after laying their eggs and will regenerate them for the next year's mating season. Interestingly, male nautiluses seem to vastly outnumber the females.

(image: nautiluses mating)

Nautiluses are found in the Indo-Pacific reagion of the ocean and can be found on the steep slopes of coral reefs. They prefer to inhabit waters several hundred meters down. It was once believed that they would rise to shallow waters at night to feed, lay eggs, and mate, but their vertical migration behavior has since been shown to be more complex than that. They have noon been fished by humans for their shells, which have become popular subjects in art and can be made into a number of decorative pieces. The nacre of the shell can be polished into osmeña pearl, which can be quite valuable. Demand for the shells combined with the late sexual maturity and low fecundity is threatening all the species. As of 2016, nautiluses have been added to the CITES Appendix II, making them protected by limiting international trade of their shells. Despite this, they are still threatened and require further protection

(image: a carved and painted nautilus shell from the Poldi Pezzoli Museum, Milan)

top 10 spooky and scary fish

happy fishy-ween everyone! these are 10 of the spookiest fish (in my opinion) although i love all fish equally so please dont take this too seriously!

10. Angler fish

A classic. Probably the first thing most people think of when you mention spooky fish. Wonderfully girlboss.

9. Gluper eel/pelican eel

look at this guy! he's so happy and smiley :))) It's lower jaw is roughly a quater of it's body length!

8. Barreleye fish

This guy is truly no thoughts head empty, my idol. Scientists speculate that it's fins are well adapted for avoiding the stinging tentacles of siphonophores.

7. the harp sponge

you might say, "eddie, why the fuck is a sponge on this list! its a sponge how the hell is it spooky?" WELL this guy is carnivorous! Sponges usually eat bacteria and other floaty things but this guy eats crustaceans of all things. Imagine you're a tiny crab and you get eaten by this!! i'd be terrified!

6. Goblin shark

this guy is also a classic spooky fish in my opinion. Love this guy! Its long nose has electrical receptors which detect the electric currents of its prey

5. Snail fish

i've included this one entirely out of pity. look at him and pretend to shake in terror so you dont upset him.

4. crown of thorns starfish

Crown of thorns starfish eat coral and phtoplankton. phytoplankton aren't common in coral reefs usually, however their numbers increase due to increasing pollutants and fertiliser run off. These starfish can cause devastation on coral reefs and this is only increasing. i'd say ecosystem destruction is pretty damn scary.

3. candiru

candiru or vampire fish are the fleas and mosquitos of the fish world. They bury themselves in the fishs' gills and use little barbs to stay in.

while i was researching this fish i found a singular story of this guy swimming up a man's ureathra in 1997 however this was subject to controversy.

2. cone snail

those who have watched the octonauts will be familiar with this guy. The cone snail is a predatory snail that use a harpoon-like projectile to subdue their prey. Should also point out that this is venomous as well. The octonauts episode that introduced this guy made baby eddie genuinely terrified. Also, some of the larger species of cone snail eat fish, and their venom can be fatal to humans.

1. Magnapinna squid

i saved this guy for first spot because i love him so much <3 i think he deserves top spot on this list. So far we have only discovered juvinille samples and there have been fewer than 15 sightings. We know basically nothing about them including what their funky tentacles are for (although it is suspected they are related to feeding)

Thank you for reading this far! hope you enjoyed learning about horrors beyond your comprehension, enjoy your spooky day