#decapods

[heartnosekid]

blue dream shrimp (neocaridina davidi) having a snack | shrimpsensei on ig

[uncharismatic-fauna]

Uncharismatic Fact of the Day

Although they look like they belong on the runway, the elegant squat lobster's vivid coloration is actually a form of camoflage. These tiny crustaceans live on plant-like creatures called crinoids, or feather stars. Their hosts are brightly colored, so to blend in Allogalathea elegans pulls out all the stops!

(Image: An elegant squat lobster (Allogalathea elegans) by Ryan Paddy)

[weirdchristmas]

This year, I'm focusing on "less is more." Which, honestly, still involves the same amount of crabs.

[hollowforms]

crawf

[artifacts-and-arthropods]

Shellback Crabs: these crabs create their own shields using clamshells, and they have semi-membranous bodies that can be pressed into the contours of the shell, producing a suction mechanism that holds it in place

Crabs of the genus Hypoconcha, commonly known as shellback crabs, are able to conceal and protect themselves by carrying discarded seashells against their backs. Many Dromiidae crabs are equipped with a specialized pair of legs that allow them to hold sea sponges, ascidians, or shells against their bodies as a defense mechanism, but shellback crabs also have flexible, semi-membranous bodies that can be tucked more firmly into the contours of a bivalve shell, producing a suction mechanism that keeps the shell firmly locked in place.

This article describes how the shellback crab carries and deploys its clamshell disguise:

Instead of a hard carapace protecting its back, this little crab is covered above with a parchment-like skin. The underside and the hands are rough and granular. Three pairs of walking legs are developed as such, but the last pair are reduced and held above its back. With these legs, this bit of a crab hoists half of a small bivalve shell on its back, tucks its angular rear into the hinge side and carries the shell for its protection.

Walking along, it resembles a wave-washed shell, but when danger threatens, it squats down and drops the protective shell to the bottom, and so it goes unnoticed.

Each crab is also covered in a very fine layer of hair-like structures known as setae, and when the crab presses itself against the inner surface of a clamshell, those membranous "hairs" can take on an almost translucent appearance, particularly around the margins of the body. This effect makes the crab itself look like nothing more than a clump of wet sand stuck to the underside of the shell.

I recently wrote a post about a species of sponge crab known as Lamarckdromia beagle, which is another weirdly adorable member of the Dromiidae family. All of the crabs in this family seem to have their own unique adaptations that allow them to use specific materials for camouflage, including discarded seashells, live sea sponges, ascidians, or bits of debris.

I just could not stop laughing at the faces on these little shellback crabs, though.

They've all got the same bemused and indignant expression, like some random jerk just walked up to them, flipped them over, and announced to the entire ocean that there's actually a crab hiding beneath that clamshell disguise; like that happens to them quite a lot, actually, and they're getting pretty sick of it.

Sources & More Info:

The Great Outdoors Book of Seashore Life: Hypoconcha arcuata

Crustaceana Monographs: Comparison of the Shell-Carrying Behaviors of Desmodromia, Conchoecetes, and Hypoconcha

South Carolina Department of Natural Resources: Shellback Crabs and their Larval Stages (PDF)

South Carolina Public Radio: Shellback Crabs

iNaturalist: Genus Hypoconcha

[patheticmosasaur1]

today's invertebrate………cherax pulcher

while it may look natural, the elegant colouration of this haughty bugger is actually a side effect of the colossal amount of sugar that has entered his body in the form of gobstoppers and cheap sour worms. some say that by now his blood has turned into complete sugar water, and his brain into a sweet gooey mush!

such a vile amount of sugar in one's system has also made his claws very jittery and his thoughts unpredictable, which isn't great because he used to be a puncher. a cherax puncher

glorpiness rating: drog!!!!!

photographed by Christian Lukhaup (CC BY 4.0)

never seen a more beautiful crawdad before

[agiantshark]

Solnhofen shrimp (Upper Jurassic), featuring fan favorites Aeger spinipes, Antrimpos speciosus and Dusa monocera and pisces indet..

I have lost my sanity over drawing shrimp legs, so I will be drawing legless animals for a while.

[taxonomytournament]

Taxonomy Tournament: Crustaceans

Decapods. This order includes crabs, lobsters, crayfish, shrimp, and prawns.

Isopoda. This order is made up of isopods, including terrestrial species like the potato bug and aquatic species like the giant isopod. Some eat dead matter, others are filter feeders, and some are parasites, mostly of fish.

Which clade of animals is better?

Decapods

Isopoda

Show results

Voting ended onMar 16, 2024